Famous Scientists -Biography Online About Famous Scientists Biographies of famous scientists throughout the ages. This list of scientists includes Aristotle, Leonardo Da Vinci, Galileo to modern day scientists, such as Einstein, Tesla and James Watson. Hippocrates (460 – 377 BC) – Hippocrates was a great doctor of ancient Greece. His pioneering techniques of health care, significantly improved survival rates and he has became the father of modern medicine. His Hippocratic oath is still sworn by medical practitioners today . Aristotle (384 – 322 BC) Greek scientist who made many researches in the natural sciences including botany, zoology, physics, astronomy, chemistry, and meteorology, geometry. His prolific output was a major impact on the study of science in the West. Euclid (c. 325 – 265 BC) Greek mathematician. Euclid is often referred to as the ‘father of modern geometry.’ His book ‘Elements‘ provided the basis of mathematics into the Twentieth Century. Archimedes (287 – 212 BC) Greek polymath Amongst other things Archimedes worked out Pi and developed the Archimedes screw for lifting up water from mines or wells.

Leonardo Da Vinci (1452 – 1519) Italian artist and renaissance man. Da Vinci made many scientific discoveries and inventions. Da Vinci was so far ahead of his time, some of his contributions were not actually used. Nicholas Copernicus (1473- 1543) Polish scientist. A Renaissance mathematician and astronomer who formulated a heliocentric view of the universe. His book On the Revolutions of the Celestial Spheres (1543) was one of the major moments of the Scientific Revolution. 17th Century Scientists Francis Bacon (1561 – 1626) English philosopher, statesman and scientist. Bacon is considered the father of empiricism for his work and advocacy of scientific method and methodical scientific inquiry in investigating scientific phenomena. Galileo (1564 – 1642) Italian scientist. Created one of the first modern telescopes, Galileo revolutionised our understanding of the world supporting the work of Copernicus. His work Two New Sciences laid ground work for science of Kinetics and strength of materials.

Johannes Kepler (1571 – 1630) German mathematician, astronomer, and astrologer. Kepler is best known for his laws of planetary motion. He formed a key figure in the 17th Century Scientific Revolution. 18th Century Scientists Antonie van Leeuwenhoe (1632 – 1723) Dutch scientist and trader. Leeuwenhoe is considered the father of micro-biology for his work in discovering single celled organisms, and also observing muscle fibres, blood flow and bacteria. He developed the microscope which helped his own discoveries. Sir Isaac Newton (1642-1726) English scientist. Newton made studies in mathematics, optics, physics, and astronomy. In his Principia Mathematica, published in 1687, he laid the foundations for classical mechanics, explaining the law of gravity and the Laws of Motion. John Harrison (1693 – 1776) English clockmaker and inventor of measuring longitude. James Watt (1736 – 1819) Scottish engineer. Watt improved the Newcomen steam engine creating an efficient steam engine, which was essential for the industrial revolution.

Antoine-Laurent de Lavoisier (1743 – 1794) French Chemist and Nobleman. Considered the ‘Father of Chemistry’ Lavoisier discovered hydrogen and Oxygen, and showed the role of Oxygen in combustion. He also made the first comprehensive list of Table of elements. He was guillotined shortly after the French Revolution. Scientists 19th Century Charles Babage (1791 – 1871) – English inventor of the first mechanical computers. Babage is considered the ‘father of computers’ for his pioneering work on mechanical computers. Michael Faraday (1791 – 1867) – English scientist who contributed in fields of electromagnetic induction, diamagnetism, electrolysis and electro-chemistry. Discovered Carbon and Chlorine. Edward Jenner (1749 – 1823) English pioneer of smallpox vaccine. Jenner’s breakthrough also enabled many other vaccines to be developed. Charles Darwin (1809 – 1882) English scientist. Developed the theory of evolution against a backdrop of disbelief and scepticism.

Collected evidence over 20 years, and published conclusions in On the Origin of Species (1859). Louis Pasteur (1822 – 1895) French biologist. Contributed greatly towards the advancement of medical sciences developing cures for rabies, anthrax and other infectious diseases. Also enabled process of pasteurisation to make milk safer to drink. Gregor Mendel (1822 – 1884) German scientist and Augustinian Friar. Mendel is considered the founder of modern genetics for his discoveries about plant breeding and rules of heredity. Joseph Lister (1827 – 1912) English surgeon. Lister pioneered the use of antiseptic (Carbolic acid) and antiseptic surgery which dramatically improved survival rates. James Clerk Maxwell (1831-1879) Scottish physicist. Maxwell made a significant contribution to understanding electro-magnetism. His research in electricity and kinetics, laid foundation for quantum physics. Emil Fischer (1838–1914) – German. Fischer was the outstanding chemist of the modern age. Synthesized many products to show their constituent parts.

Won the Nobel Prize in Chemistry in 1902 for his research into the chemical composition of purines and sugars. Scientists 20th Century Alfred Nobel (1833 – 1896) Swedish chemist, engineer, innovator, and armaments manufacturer. Nobel invented dynamite and held 350 other patents, including for a gas meter. Perhaps most famous for his legacy of Nobel awards. Dmitri Mendeleev (1834 – 1907) Russian Chemist. Formulated the Periodic Law and standardised Periodic Table of Elements which is still used today. Mendeleev wrote Principles of Chemistry (1868–1870) a classic textbook for many decades. Alexander Bell (1847 – 1922) – Scottish inventor of telephone and developments in understanding hearing. Sigmund Freud (1885 – 1939) Austrian physician – the leading figure in new science of psychoanalysis. Freud made extensive study of dreams and the sub-conscious to try and understand better human emotions. Marie Curie (1867 – 1934) Polish physicist and chemist.

Discovered radiation and helped to apply it in the field of X ray. She won Nobel Prize in both Chemistry and Physics. Albert Einstein (1879 – 1955) German/ US. Revolutionised modern physics with his general theory of relativity. Won Nobel Prize in Physics (1921) for his discovery of the Photoelectric effect, which formed the basis of Quantum Theory. Alexander Fleming (1881-1955) Scottish biologist who discovered penicillin. Shared Nobel Prize in 1945 with Howard Florey and Enrst Boris Chain, who helped produce penicillin on a large scale. Otto Hahn (1879-1968) – German chemist who discovered nuclear fission (1939). Pioneering scientist in the field of radio-chemistry. Discovered radio-active elements and nuclear isomerism (1921). Awarded Nobel Prize for Chemistry (1944) Nikola Tesla (1856 –1943) Serbian/American – Worked on electro-magnetism and AC current. Credited with many patents from electricity to radio transmission.

Sri Jagadish Chandra Bose (1858 – 1937) Bengali / Indian polymath. Bose took an interest in a wide range of sciences. He made contributions to plant physiology, microwave optics and radio waves. Max Plank (1858 – 1947) German theoretical physicist who contributed to the development of Quantum mechanics. Awarded the Nobel Prize for Physics in 1918. Ernest Rutherford (1871 – 1937) New Zealand born British physicist / Chemist. Rutherford was awarded Nobel Prize for Chemistry in 1908 for his work into radioactivity and disintegration of elements. In 1917, credited with being the first person to split the atom, discovering the proton. Niels Bohr (1885 – 1962) Danish physicist. Bohr developed a structure of the atom, recognising electrons revolving around a stable nucleus. His work was important for atomic structure and quantum physics. Awarded Nobel Prize for physics 1922.

John Logie Baird (1888 – 1946) was a Scottish engineer and inventor, who demonstrated the first televised moving objects. Satyendra Nath Bose (1894 – 1974) Indian physicist who worked on quantum mechanics. Collaborated with A.Einstein to found Bose-Einstein statistics and Bose-Einstein condensate. Paul Dirac (1902-1984) English physicist – One of the early exponents of quantum physics and quantum electrodynamics. Dirac developed theories of the electron and the special theory of relativity. Rosalind Franklin (1920 – 1958) British Chemist who made significant contributions to understanding the structure of DNA and RNA, which led to the discovery of the DNA double helix. Franklin also worked on the chemistry of coal and viruses. James Watson (1928 – ) American molecular biologist, geneticist and zoologist, with Francis Crick discovered DNA. Was awarded the Nobel Prize in 1962 21st Century Scientists Stephen Hawking (1942 – ) English theoretical physicist, cosmologist.

Hawking has authored The Theory of Everything, and A Brief History of Time. Citation : Pettinger, Tejvan . “Famous Scientists” Oxford, UK – . Last updated 12th Jan. 2015 Atoms - What are they? What's inside them? - Explain that Stuff Tweet by Chris Woodford . Last updated: April 6, 2016. Suppose you had to build yourself a world exactly like the one we live in. Where would you start? You'd need people... cars... houses... animals... trees... and billions of other things. But if you had a few dozen different types of atom, you could build all these things and more: you'd just join the atoms together in different ways. Atoms are the tiny building blocks from which everything around us is constructed. It's amazing to think you can make anything out of atoms, from a snake to an ocean liner—but it's absolutely true! Let's take a closer look. Photo: Methane molecules flying down a tiny carbon nanotube. Courtesy of US Department of Energy . What is an atom? Take anything apart and you'll find something smaller inside.

There are engines inside cars, pips inside apples, hearts and lungs inside people, and stuffing inside teddy bears. But what happens if you keep going? If you keep taking things apart, you'll eventually, find that all matter (all the "stuff" that surrounds us) is made from different types of atoms. Living things, for example, are mostly made from the atoms carbon, hydrogen, and oxygen. These are just three of over 100 chemical elements that scientists have discovered. Other elements include metals such as copper , tin , iron and gold , and gases like hydrogen and helium. You can make virtually anything you can think of by joining atoms of different elements together like tiny LEGO® blocks. An atom is the smallest possible amount of a chemical element—so an atom of gold is the smallest amount of gold you can possibly have. By small, I really do mean absolutely, nanoscopically tiny: a single atom is about 100,000 times thinner than a human hair, so you have absolutely no chance of ever seeing one unless you have an incredibly powerful electron microscope . In ancient times, people thought atoms were the smallest possible things in the world.

In fact, the word atom comes from a Greek word meaning something that cannot be split up any further. Today, we know this isn't true. In theory, if you had a knife small and sharp enough, you could chop an atom of gold into bits and you'd find smaller things inside. But then you'd no longer have the gold: you'd just have the bits. All atoms are made from the same bits, which are called subatomic particles ("sub" means smaller than and these are particles smaller than atoms). So if you chopped up an atom of iron, and put the bits into a pile, and then chopped up an atom of gold, and put those bits into a second pile, you'd have two piles of very similar bits—but there'd be no iron or gold left. Photo (above): What does an atom look like? You can see one if you have the right kind of microscope ! This photo shows sulfur atoms arranged on a layer of copper deposited onto a crystal of ruthenium. By courtesy of US Department of Energy/Brookhaven National Laboratory. What are the parts of an atom? Most atoms have three different subatomic particles inside them: protons, neutrons, and electrons.

The protons and neutrons are packed together into the center of the atom (which is called the nucleus) and the electrons, which are very much smaller, whizz around the outside. When people draw pictures of atoms, they show the electrons like satellites spinning round the Earth in orbits. In fact, electrons move so quickly that we never know exactly where they are from one moment to the next. Imagine them as super-fast racing cars moving so incredibly quickly that they turn into blurry clouds—they almost seem to be everywhere at once. That's why you'll see some books drawing electrons inside fuzzy areas called orbitals. Artwork: Atoms contain protons and neutrons packed into the central area called the nucleus, while electrons occupy the space around it. In simple descriptions of the atom, we often talk about electrons "orbiting" the nucleus like planets going around the Sun or satellites whizzing around Earth, although that's a huge oversimplification , as chemistry teacher Jim Clarke points out very clearly. Note also that this picture isn't drawn to scale! Most of an atom is empty space.

If an atom were about as big as a baseball stadium, the nucleus would be the size of a pea in the very center and the electrons would be somewhere on the outside edge. What makes an atom of gold different from an atom of iron is the number of protons, neutrons, and electrons inside it. Cut apart a single atom of iron and you will find 26 protons and 30 neutrons clumped together in the nucleus and 26 electrons whizzing around the outside. An atom of gold is bigger and heavier. Split it open and you'll find 79 protons and 118 neutrons in the nucleus and 79 electrons spinning round the edge. The protons, neutrons, and electrons in the atoms of iron and gold are identical—there are just different numbers of them. In theory, you could turn iron into gold by taking iron atoms and adding 53 protons, 88 neutrons, and 53 electrons to each one. But if that were as easy as it sounds, you can bet all the world's chemists would be very rich indeed! But let's suppose you could turn atoms into other atoms very simply. How would you make the first few chemical elements?

You'd start with the simplest atom of all, hydrogen (symbol H), which has one proton and one electron, but no neutrons. If you add another proton, another electron, and two neutrons, you get an atom of helium (symbol He). Add a further proton, another electron, and two more neutrons, and you'll have an atom of the metal lithium (symbol Li). Add one proton, one neutron, and one electron and you get an atom of beryllium (symbol Be). See how it works? In all atoms, the number of protons and the number of electrons is always the same. The number of neutrons is very roughly the same as the number of protons, but sometimes it's rather more. The number of protons in an atom is called the atomic number and it tells you what type of atom you have. An atomic number of 1 means the atom is hydrogen, atomic number 2 means helium, 3 means lithium, 4 is beryllium, and so on. The total number of protons and neutrons added together is called the relative atomic mass.

Hydrogen has a relative atomic mass of 1, while helium's relative atomic mass is 4 (because there are two protons and two neutrons inside). In other words, an atom of helium is four times heavier than an atom of hydrogen, while an atom of beryllium is nine times heavier. How do atoms make molecules and compounds? Atoms are a bit like people: they usually prefer company to being alone. A lot of atoms prefer to join up with other atoms because they're more stable that way. So hydrogen atoms don't exist by themselves: instead, they pair up to make what is called a molecule of hydrogen. A molecule is the smallest amount of a compound: a substance made from two or more atoms. Some people find molecules and compounds confusing. Here's how to remember the difference. If you join two different chemical elements together, you can often make a completely new substance. Glue two atoms of hydrogen to an atom of oxygen and you'll make a single molecule of water . Water is a compound (because it's two different chemical elements joined together), but it's also a molecule because it's made by combining atoms. The way to remember it is like this: compounds are elements joined together and molecules are atoms joined together.

Not all molecules are as small and simple as water. Molecules of plastics , for example, can be made of hundreds or even thousands of individual atoms joined together in incredibly long chains called polymers. Polythene (also called polyethene or polyethylene) is a very simple example of this. It's a polymer made by repeating a basic unit called a monomer over and over again—just like a coal train made by coupling together any number of identical trucks, one after another: What are isotopes? To complicate things a bit more, we sometimes find atoms of a chemical element that are a bit different to what we expect. Take carbon, for example. The ordinary carbon we find in the world around us is sometimes called carbon-12. It has six protons, six electrons, and six neutrons, so its atomic number is 6 and its relative atomic mass is 12. But there's also another form of carbon called carbon-14, with six protons, six electrons, and eight neutrons. It still has an atomic number of six, but its relative atomic mass is 14.

Carbon-14 is more unstable than carbon-12, so it's radioactive: it naturally disintegrates, giving off subatomic particles in the process, to turn itself into nitrogen. Carbon-12 and carbon-14 are called isotopes of carbon. An isotope is simply an atom with a different number of neutrons that we'd normally expect to find. How do atoms make ions? Atoms aren't just packets of matter: they contain electrical energy too. Each proton in the nucleus of an atom has a tiny positive charge ( electricity that stays in one place). We say it has a charge of +1 to make everything simple (in reality, a proton's charge is a long and complex number: +0.00000000000000000016021892 C, to be exact!). Neutrons have no charge at all. That means the nucleus of an atom is effectively a big clump of positive charge. An electron is tiny compared to a proton, but it has exactly the same amount of charge.

In fact, electrons have an opposite charge to protons (a charge of −1 or −0.00000000000000000016021892 C, to be absolutely exact). So protons and electrons are a bit like the two different ends of a battery : they have equal and opposite electric charges. Since an atom contains equal number of protons and electrons, it has no overall charge: the positive charges on all the protons are exactly balanced by the negative charges on all the electrons. But sometimes an atom can gain or lose an electron to become what's called an ion. If it gains an electron, it has slightly too much negative charge and we call it a negative ion; it it loses an electron, it becomes a positive ion. Artwork: A lithium atom (Li) forms a positive ion (Li +) by "losing" an electron. A fluorine atom (F) forms a negative ion (F −) by gaining an electron. What's so good about ions? They're very important in many chemical reactions.

For example, ordinary table salt (which has the chemical name sodium chloride) is made when ions of sodium join together with ions made from chlorine (which are called chloride ions). A sodium ion is made when a sodium atom loses an electron and becomes positively charged. A chloride ion forms in the opposite way when a chlorine atom gains an electron to become negatively charged. Just like two opposite magnet poles, positive and negative charges attract one another. So each positively charged sodium ion snaps onto a negatively charged chloride ion to form a single molecule of sodium chloride. When compounds form through two or more ions joining together, we call it ionic bonding. Most metals form their compounds in this way. The electrical charge that ions have can be useful in all sorts of ways. Ions (as well as electrons) help to carry the electricity through batteries when you connect them into a circuit. How do we know atoms exist? If we can't see atoms, how do we know they're there? That's a very good question! Science is all about evidence, so what evidence do we have that atoms really exist? It comes in a variety of different forms: Chemists have long known that when we combine different elements in chemical reactions, the ingredients join in simple ratios.

So, for example, in water we know that there are twice as many hydrogen atoms as oxygen atoms (H2O), making a ratio of 2:1. In salt (sodium chloride) there are equal numbers of sodium and chlorine atoms (NaCl), so the ratio is 1:1. We can easily explain this if chemical elements really exist as simple particles (atoms, in other words), which snap together like building blocks. Some substances are radioactive: they naturally split into simpler substances and give off tiny particles or energy in the process. Again, this makes sense if atoms exist and they're built from smaller particles (protons, neutrons, and electrons). Scientists can split big atoms into smaller ones. In one very famous series of experiments in the early 20th century, a team led by Ernest Rutherford (a New-Zealand-born physicist) fired particles at atoms and watched what happened. This showed how the bits were arranged inside a typical atom (with the nucleus at the center). We have plenty of evidence for tiny particles called electrons: they power things like electricity and magnetism . An English physicist named J.J. Thomson discovered electrons in 1897.

This discovery helped scientists to realize that atoms are made of even smaller bits. Unlike these earlier scientists, we can actually see atoms; just look at the photo of sulfur atoms up above! Seeing that picture would have delighted Rutherford, Thomson, and the other pioneers of atomic science. Now, scientists are even starting to see inside atoms. Thanks to the development of really powerful electron microscopes , we can peer deep inside things at their internal atomic structure. In 2013, for example, scientists used a quantum microscope to produce the first picture of the inside of a hydrogen atom . Amazing! There's plenty more evidence where that came from, but this will do for starters. It shows us that our theory of what atoms are and how they are built is a very good one: the theory agrees with the things we see around us in the world and it's confirmed by many different kinds of evidence. It's not a complete theory, however: we still have an enormous amount to learn about atoms and the bits and pieces lurking inside them! Artwork: Molecules are built from atoms: In the early 19th century, English chemist John Dalton (1766–1844) realized that atoms join together in simple ratios.

Water forms when two hydrogens snap onto one oxygen. Chemical reactions like this make sense if the elements exist as simple building blocks: atoms, in other words. A brief history of atoms Who discovered the atom, how, and when? Let's quickly nip back through history... 450 BCE: Ancient Greek philosophers Leucippus and Democritus became the first people to propose that matter is made of atoms. 1661: Anglo-Irish chemist Robert Boyle (1627–1691) suggested that chemical elements were the simplest forms of matter. 1803: English scientist John Dalton (1766–1844) published the atomic theory of matter. He realized each chemical element was made up of atoms. 1869: A Russian chemist called Dmitri Mendeleyev (1834–1907) found a logical way of organizing the chemical elements with a neat structure called the Periodic Table. 1896: French physicist Henri Becquerel (1852–1908) accidentally discovered radioactivity.

1911: New Zealand-born English physicist Ernest Rutherford (1871–1937) "split" the atom: he proved that atoms are made of smaller particles, eventually concluding they had a heavy, positively charged nucleus and a largely empty area around them. Ernest Rutherford, Scientist • Biography & Facts Ernest Rutherford Scientist "Lord Rutherford" redirects here; not to be confused with Lord Rutherfurd or with Andrew Rutherford, 1st Earl of Teviot.Ernest Rutherford, 1st Baron Rutherford of Nelson, OM FRS (30 August 1871 – 19 October 1937) was a New Zealand-born British physicist who became known as the father of nuclear physics. Encyclopædia Britannica considers him to be the greatest experimentalist since Michael Faraday (1791–1867).In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation. This work was done at McGill University in Canada.

It is the basis for the Nobel Prize in Chemistry he was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances".Rutherford moved in 1907 to the Victoria University of Manchester (today University of Manchester) in the UK, where he and Thomas Royds proved that alpha radiation is helium nuclei. Rutherford performed his most famous work after he became a Nobel laureate. In 1911, although he could not prove that it was positive or negative,he theorized that atoms have their charge concentrated in a very small nucleus,and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment. He is widely credited with first "splitting the atom" in 1917 in a nuclear reaction between nitrogen and alpha particles, in which he also discovered (and named) the proton.Rutherford became Director of the Cavendish Laboratory at Cambridge University in 1919.

Under his leadership the neutron was discovered by James Chadwick in 1932 and in the same year the first experiment to split the nucleus in a fully controlled manner, performed by students working under his direction, John Cockcroft and Ernest Walton . After his death in 1937, he was honoured by being interred with the greatest scientists of the United Kingdom, near Sir Isaac Newton 's tomb in Westminster Abbey. The chemical element rutherfordium (element 104) was named after him in 1997. Personal facts General Chemistry/Atomic Structure/History of Atomic Structure - Wikibooks, open books for an open world General Chemistry/Atomic Structure/History of Atomic Structure From Wikibooks, open books for an open world 10 References Why Is The History Of The Atom So Important?[ edit ] It is fundamental to the understanding of science that science is understood to be a process of trial and improvement and represents the best known at the time, not an unerring oracle of truth. Development of an idea and refinement through testing is shown more in the understanding of atomic structure.

The Greek Theorists[ edit ] A bust of Democritus (or Democrites), who came up with the idea of indivisible atoms. The earliest known proponent of anything resembling modern atomic theory was the ancient Greek thinker Democritus. He proposed the existence of indivisible atoms as a response to the arguments of Parmenides, and the paradoxes of Zeno. Parmenides argued against the possibility of movement, change, and plurality on the premise that something cannot come from nothing. Zeno attempted to prove Parmenides' point by a series of paradoxes based on difficulties with infinite divisibility. In response to these ideas, Democritus posited the existence of indestructible atoms that exist in a void. Their indestructibility provided a retort to Zeno, and the void allowed him to account for plurality, change, and movement. It remained for him to account for the properties of atoms, and how they related to our experiences of objects in the world. Democritus proposed that atoms possessed few actual properties, with size, shape, and mass being the most important. All other properties, he argued, could be explained in terms of the three primary properties.

A smooth substance, for instance, might be composed of primarily smooth atoms, while a rough substance is composed of sharp ones. Solid substances might be composed of atoms with numerous hooks, by which they connect to each other, while the atoms of liquid substances possess far fewer points of connection. Democritus proposed 5 points to his theory of atoms. [1] These are: All matter is composed of atoms, which are bits of matter too small to be seen. These atoms CANNOT be further split into smaller portions. There is a void, which is empty space between atoms. Atoms are completely solid. Alchemy[ edit ] Although alchemy was futile, the alchemists did come up with several useful methods, including distillation (shown here). A fire, shown by Lavoisier to be a chemical reaction and not an element. Empedocles proposed that there were four elements, air, earth, water, and fire and that everything else was a mixture of these. This belief was very popular in the medieval ages and introduced the science of alchemy. Alchemy was based on the belief that since everything was made of only four elements, you could transmute a mixture into another mixture of the same type.

For example, it was believed that lead could be made into gold. Alchemy's problem was exposed by Antoine Lavoisier when he heated metallic tin in a sealed flask. A grayish ash appeared on the surface of the melting tin, which Lavoisier heated until no more ash formed. After the flask cooled, he inverted it and opened it underwater. He discovered the water rose one-fifth of the way into the glass, leading Lavoisier to conclude that air itself is a mixture, with one-fifth of it having combined with the tin, yet the other four-fifths did not, showing that air was not an element. Lavoisier repeated the experiment again, substituting mercury for tin, and found that the same happened. Yet after heating gently, he found that the ash released the air, showing that the experiment could be reversed. He concluded that the ash was a compound of the metal and oxygen, which he proved by weighing the metal and the ash, and showing that their combined weight was greater than that of the original metal. Lavoisier then stated that combustion was not an element, but instead was a chemical reaction of a fuel and oxygen. John Dalton[ edit ] Different elements, different atoms.

Modern atomic theory was born with Dalton when he published his theories in 1803. His theory consists of five important points, which are considered to be mostly true today: (from Wikipedia) Elements are composed of tiny particles called atoms. All atoms of a given element are identical. The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative weights. Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative numbers of types of atoms. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together. We now know that elements have different isotopes, which have slightly different weights. Also, nuclear reactions can divide atoms into smaller parts (but nuclear reactions aren't really considered chemical reactions). Otherwise, his theory still stands today. Dmitri Mendeleev[ edit ] In the late 1800's, Russian scientist Dmitri Mendeleev was credited with creating one of the first organized periodic tables. Organizing each element by atomic weight, he cataloged each of the 56 elements discovered at the time.

Aside from atomic weight, he also organized his table to group the elements according to known properties. While writing a series of textbooks, Mendeleev realized he was running out of space to treat each element individually. He began to regularly "linewrap" the elements onto the next line, and create what is now called the periodic table of the elements. Using his table, he predicted the existence of later-discovered elements, such as "eka-aluminum" and "eka-silicon" (gallium and germanium) according to patterns found earlier. His predictions were a success, proving his table to be exceptionally accurate. Later theories, those of the electrons around the atom, explain why elements in the same period, or group, have similar chemical properties. Chemists would later organise each element by atomic number, not atomic weight, giving rise to the modern Periodic Table of Elements . Discovery of the Electron[ edit ] Cathode rays are actually made of electrons. In the year 1889 the British physicist J.J. Thomson discovered the electron. Thomson conducted a number of experiments using cathode ray tube.

Cathode rays are constructed by sealing two electrodes in a glass tube connected to a voltage supplier and a vacuum pump removing the air from it. When the electrodes are attached to high voltage of about 15000v and low pressure, a beam of radiation is emitted from the negative electrode(cathode)moving towards the positive electrode(anode). These beams are said to be green rays called cathode rays. (1) The ray is said to be taken towards Faraday's tube(gold leaf electroscope) and was charged by induction and deflect positively charged gold leaf electroscope (2) a freely moving paddle wheel was placed on the path of the rays and it was able to move it suggesting that it has momentum (3) The ray was placed in a magnetic and electric field moving towards the north and positive pole respectively Thomson discovered that cathode rays travel in straight lines except, when they are bent by electric or magnetic fields. The cathode rays bent away from a negatively charged plate, Thomson concluded that these rays are made of negatively charged particles; today we call them electrons. Thomson found that he could produce cathode rays using electrodes of various materials.

He then concluded that electrons were found in all atoms and are over a thousand times smaller than protons. Thompson used an apparatus to determine the charge to mass ratio(e/m)after the ray emerge he placed a magnetic field of a known magnetic influence and the rays bent towards the north to a particular position then he added an electric field to return the ray back to it original position and recorded the charges used by the electric field so he divided them to get the ratio of about -1.7*10^8 The "Plum Pudding" Atomic Model[ edit ] Soon after the discovery of the electron, Thomson began speculating on the nature of the atom. He suggested a "plum pudding" model. In this model the bits of "plum" were the electrons which were floating around in a "pudding" of positive charge to match that of the electrons and make an electrically neutral atom. A modern illustration of this idea would be a chocolate chip cookie, with the chips representing negatively charged electrons and the dough representing positive charge.

Rutherford[ edit ] The results of the gold foil experiment disproved the "plum pudding" model: the alpha particles should have passed through (top), but a few of them deflected at large angles (bottom). Ernest Rutherford is known for his famous gold foil experiment in 1911. Alpha particles, which are heavy and positively charged (actually, helium nuclei, but that's beside the point), were fired at a very thin layer of gold. Most of the alpha particles passed straight through, as expected. According to the plum pudding model all of the particles should have slowed as they passed through the "pudding", but none should have been deflected. Surprisingly, a few alpha particles were deflected back the way they came. He stated that it was "as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you." The result of the experiment allowed Rutherford to conclude that the plum pudding model is wrong. Atoms have a nucleus, very small and dense, containing the positive charge and most of the atom's mass. The atom consists of mostly empty space. The electrons are attracted to the nucleus, but remain far outside it.

Niels Bohr[ edit ] The Bohr model of the atom has shells with numbered spherical energy levels - the larger numbers mean larger spheres and higher energy levels. The wave exiting the picture on the left has come from an electron jump, resulting in a photon. (Level sizes not to scale.) Bohr created his own model of the atom, improving on Rutherford's. Bohr used an equation developed by Rydberg that provided a mathematical relationship between the visible spectral lines of the hydrogen atom. The equation requires that the wavelengths emitted from the hydrogen atom be related to the difference of two integers. Bohr theorized that these integers represent "shells" or "orbits" in which electrons travel around the nucleus, each with a certain energy level. The energy of an orbit is proportional to its distance from the nucleus. An atom will absorb and release photons that have a specific amount of energy. The energy is the result of an electron jumping to a different shell. Starting with Rydberg's equation, along with Planck and Einstein's work on the relationship between light and energy, Bohr was able to derive an equation to calculate the energy of each orbit in the hydrogen atom.

The Bohr model depicts the atom as a nucleus with electrons orbiting around it at specific distances. This model is also referred to as the Planetary Model. Millikan[ edit ] Robert Millikan is accredited for the "Oil Drop Experiment", in which the value of the electron charge was determined. He created a mechanism where he could spray oil drops that would settle into a beam of X rays. The beam of X rays caused the oil drops to become charged with electrons. The oil droplets were in between a positively charged plate and a negatively charged plate which, when proper electric voltage was applied, caused the oil droplet to remain still. Robert Millikan measured the diameter of each individual oil drop using a microscope. Millikan was able to calculate the mass of each oil droplet because he knew the density of the oil ( v BBC - Manchester - Rutherford: splitting the atom Rutherford: splitting the atom Ernest Rutherford (right) and Hans Geiger, physics laboratory, Manchester University c.1913 There are few discoveries in science that can be said to have changed the world but one must surely be the 'splitting of the atom' by Ernest Rutherford in Manchester.

Rutherford was a New Zealander, who came to Manchester in 1907 to take up the the position of Chair of Physics at the University. Rutherford performed hundreds of radioactivity experiments He was already a notable scientist, winning the Nobel Prize for Chemistry for his work on the disintegration of elements and the chemistry of radioactive substances in Canada. But in Manchester, he was quickly on his way towards greater discoveries, aided by one of the finest teams of scientists ever assembled. Included in his 'nuclear family' were Hans Geiger, who would go on to invent the radiation counter; Lawrence Bragg, who won the 1915 Nobel Prize for his work on X-ray crystallography; Ludwig Wittgenstein, the analytic philosopher; and the great Niels Bohr, seen by many as the most gifted scientist of the 20th Century. Little wonder then that the city became a global centre for scientific research focussed on Rutherford, a man of such brilliance and repute that Albert Einstein would later call him "a second Newton". Discovering the nucleus It was one particular line of investigation though that would eventually put Rutherford alongside Darwin and Einstein in the great pantheon of science - his studies of the atom.

THE RUTHERFORD INQUIRY A 2009 inquiry found no evidence that six cancer deaths at the Rutherford Building were the result of radioactive contamination Shortly after arrival, along with Hans Geiger, he invented the Rutherford-Geiger detector which allowed him to detect individual nuclear particles by electrical means. This in turn set Rutherford on a path to discover what lay within a single atom. Through a series of experiments conducted at his laboratory just off Oxford Road, he determined that the the mass of an atom was concentrated in its nucleus - a particle 1,000 times smaller than the atom itself - with the rest being made of a cloud of orbiting electrons. It was a discovery that changed the face of science. Prior to that, the atom had been presumed to be the smallest particle in the universe. Now, Rutherford was on the verge of 'splitting the atom'. In 1911, he presented his new model of atomic structure and then set about planning the experiments that would prove the idea that, just like the atom, the nucleus itself had smaller components.

War The outbreak of war in 1914 interrupted Rutherford's research and saw his talents re-directed towards submarine technology and underwater acoustics, rather than physics. Rutherford is remembered as the father of nuclear physics But in 1916, he was allowed to resume his atomic work at his laboratory on Bridgeford Street where he carried out hundreds of experiments using radioactive material. A year later, he discovered that he could disintegrate the nuclei of nitrogen atoms by firing particles from a radioactive source which, in turn, resulted in the release of fast protons. This was the first ever artificially-induced nuclear reaction, a breakthrough that would lead ultimately to nuclear power and the atomic bombs that devastated Hiroshima and Nagasaki in World War II. In essence, Rutherford had not only created a new scientific discipline, that of nuclear physics, but also changed the world forever. All images reproduced with kind permission of the Alexander Turnbull Library, Wellington, New Zealand. Permission must be obtained before any re-use of these images.

Bookmark with: Essay on Rutherford - Scientist EssayDepot.com OPEN DOCUMENT Ernest Rutherford, 1st Baron Rutherford of Nelson OM, FRS[1] (30 August 1871 – 19 October 1937) was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics.[2] In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation. This work was done at McGill University in Canada. It is the basis for the Nobel Prize in Chemistry he was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances".[3] Rutherford performed his most famous work after he had moved to the U.K. in 1907 and was already a Nobel laureate. In 1911, he postulated that atoms have their positive charge concentrated in a very small nucleus,[4] and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment.

He is widely credited with first "splitting the atom" in 1917 in a nuclear reaction between nitrogen and alpha particles, in which he also discovered (and named) the proton.[5] This led to the first experiment to split the nucleus in a fully controlled manner, performed by two students working under his direction, John Cockcroft and Ernest Walton, in 1932. After his death in 1937, he was honoured by being interred with the greatest scientists of the United Kingdom, near Sir Isaac Newton's tomb in Westminster Abbey. The chemical element rutherfordium (element 104) was named for him in 1997.

Question: Which New Zealand-born scientist is credited with being the first to 'split the atom'?
Answer: (Ernest) RUTHERFORD