### substance | atom:

Isotope
* All isotopes produce weak gamma on decay.
* Determine the mass and number of neutrons in each of the following isotopes.
* Every isotope has a specific half-life.
* Many isotopes are radioactive, usually decaying away to other elements in a short period of time
  - stable and retain their structure indefinitely
  - unstable and they are said to be radioactive
  - contain combinations of neutrons and protons that are unstable
* Most isotopes found in nature are stable
  - give off their energy so rapidly that they are like flash bulbs
* Some isotopes are much more prevalent than others
  - radioactive, they undergo a transformation to gain a stable condition
  - radioisotopes, which spontaneously decay, releasing radioactivity
  - stable and remain unchanged through time
* Some isotopes are stable, but others are radioactive
  - some are unstable or radioactive
* Some isotopes are unstable and break down from one isotope to another
  - disintegrate naturally through a process called radioactive decay
  - which results in radioactivity
  - combine with oxygen
  - decay in hours or even minutes, but others decay very slowly
  - exhibit radioactivity, and over a period decay into an isotope of a different element
  - found in nature are unstable - their nuclei break apart or decay
  - have half-lives of a billion years or more, others are a tiny fraction of a second
  - pass through livers
* always have the same numbers of electrons and protons and therefore react in the same way.
* are a family of atoms all of which have the same number of electrons
  - a. atoms that have the same atomic number but different mass numbers
* are also extensively used in medical imaging
  - the source of radiation used in medical diagnostic and treatment procedures
  - atomic variants of the same element that differ in the number of neutrons they contain
  - atoms of an element that have a different number of neutrons in the nucleus
* are atoms of the same element that contain different numbers of neutrons
  - that have different number of neutrons within their nuclei
  - that have different numbers of neutrons
  - that vary in the number of neutrons in their nuclei
  - with a different number of neutrons
  - with different amounts of neutrons
  - with different masses
  - with different numbers of electrons
  - that are chemically identical, but have different numbers of neutrons
* are atoms which have the same atomic number but different mass numbers
  - number of protons but different numbers of neutrons
* are atoms with different atomic masses which have the same atomic number
  - the same number of protons but different neutrons
  - crucial even for geology and archeology
  - denoted by their elemental symbol preceded by the mass number
* are different atoms of the same chemical element that have slightly different mass
  - forms of an atom of the same chemical element
* are different forms of the same element, differing only by a small nuclear mass difference
  - in weight from single elements
  - variations of the same element
* are elements with different atomic masses due to different neutrons
  - similar chemical properties but different atomic weights
  - extremely powerful tools for investigating many areas of natural science
* are forms of atoms with different numbers of neutrons
  - elements with differing numbers of neutrons in the nuclei of their atoms
  - the same element that vary in the number of neutrons they contain
  - radioactive, and decay with a characteristic half-life
  - specific forms of elements
* are the result of atoms having the same atomic number but different atomic masses
  - same as the different types of apples
  - siblings of the elemental world
  - when an atom has varying number of neutrons
* can be stable or unstable, depending on how many more neutrons than protons they have
  - emitt electrons, photons, protons, neutrons, alpha particles
  - have a weight either more or less than the average
* containing both a magic number of protons and neutrons are especially stable.
* differ by the number of neutrons present in the nucleus
  - from atoms in the number of neutrons contained in the atomic nucleus
  - in mass
* fractionate when they change states, such as going from a solid to a gas.
* generally have similar chemical properties, but often different nuclear composition.
* have different chemical properties and different nuclear composition
  - properties, but generally the same nuclear composition
  - mass numbers , though , because they have different numbers of neutrons
  - similar chemical properties and the same nuclear composition
* have the same atomic mass and different atomic numbers
  - chemical properties and are the same element
  - very similar chemical properties but sometimes differ greatly in nuclear stability
* includes nucleons
  - sections
* show the same lines, but slightly shifted in wavelength.
* try to decay to more stable isotopes.
* vary in the number of neutrons present in the nucleus.
+ Atomic theory, Lord Rutherford atomic model: Nuclear physics :: Chemistry
  * By this stage the main elements of the atom were clear, plus the discovery that atoms of an element may occur in isotopes. Isotopes vary in the number of neutrons present in the nucleus. Although this model was well understood, modern physics has developed further, and present-day ideas cannot be made easy to understand. Some idea of present-day atomic physics can be got from the links in the table below.
  * Different isotopes of the same element have the same atomic number. They have the same number of protons. The atomic number is decided by the number of protons. Isotopes have different mass numbers, though, because they have different numbers of neutrons.
  * Some isotopes are radioactive. These are called radioactive isotopes. Others are not radioactive. These are called stable isotopes.
+ Zinc: Chemical elements :: Transition metals
  * It is a transition metal, a group of metals. It is sometimes considered a post-transition metal. Zinc is the 30th element on the periodic table, and has an atomic number of 30. Zinc has a mass number of 65.38. It contains 30 protons and 30 electrons. Some isotopes are radioactive. Their half-lives are between 40 milliseconds for 57Zn and 5x1018 years for 70Zn.