Electrons take part in gravitational, electromagnetic and weak interactions. The electromagnetic force is strongest in common situations. Electrons repel (push apart) from each other because they have the same electric charge. Electrons are attracted to protons because they have opposite electric charge. An electron has an electric field, which describes these forces. The electricity that powers televisions, motors, mobile phones, and many other things is actually many electrons moving through wires or other conductors.
Electrons have the smallest electrical charge. This electrical charge equals the charge of a proton, but has the opposite sign. For this reason, electrons are attracted towards the protons in atomic nuclei. This attraction makes electrons near a nucleus form an atom.
An electron has a mass of about 1/1836 times a proton.
One way to think about the location of electrons in an atom is to imagine that they orbit at fixed distances from the nucleus. This way, electrons in an atom exist in a number of electron shells surrounding the central nucleus. Each electron shell is given a number 1, 2, 3, and so on, starting from the one closest to the nucleus (the innermost shell). Each shell can hold up to a certain maximum number of electrons. The distribution of electrons in the various shells is called electronic arrangement (or electronic form or shape). Electronic arrangement can be shown by numbering or an electron diagram. (A different way to think about the location of electrons is to use quantum mechanics to calculate their atomic orbitals.)The electron is one of a type of subatomic particles called leptons. The electron has a negative electric charge. The electron has another property, called spin. Its spin value is 1/2, which makes it a fermion.
While most electrons are found in atoms, others move independently in matter, or together as cathode rays in a vacuum. In some superconductors, electrons move in pairs. When electrons flow, this flow is called electricity, or an electric current.
An object can be described as 'negatively charged' if there are more electrons than protons in an object, or 'positively charged' when there are more protons than electrons. Electrons can move from one object to another when touched. They may be attracted to another object with opposite charge, or repelled when they both have the same charge. When an object is 'grounded', electrons from the charged object go into the ground, making the object neutral. This is what lightning rods (lightning conductors) do.
Electrons in their shells round an atom are the basis of chemical reactions. Complete outer shells, with maximum electrons, are less reactive. Outer shells with less than maximum electrons are reactive. The number of electrons in atoms is the underlying basis of the chemical periodic table.
Electric "charge" can be directly measured with a device called an . Electric "current" can be directly measured with a galvanometer. The measurement given off by a galvanometer is different from the measurement given off by an . Today laboratory instruments are capable of containing and observing individual electrons.
In laboratory conditions, the interactions of individual electrons can be observed by means of particle detectors, which allow measurement of specific properties such as energy, spin and charge. In one instance a was used to contain a single electron for 10 months. The magnetic moment of the electron was measured to a precision of eleven digits, which, in 1980, was a greater accuracy than for any other physical constant.
The first video images of an electron's energy distribution were captured by a team at Lund University in Sweden, February 2008. The scientists used extremely short flashes of light, called attosecond pulses, which allowed an electron's motion to be observed for the first time. The distribution of the electrons in solid materials can also be visualized.
The antiparticle of the electron is called a positron. This is identical to the electron, but carries electrical and other charges of the opposite sign. When an electron collides with a positron, they may scatter off each other or be totally annihilated, producing a pair (or more) of gamma ray photons.
The effects of electrons were known long before it could be explained. The Ancient Greeks knew that rubbing amber against fur attracted small objects. Now we know the rubbing strips off electrons, and that gives an electric charge to the amber.
Many physicists worked on the electron. J.J. Thomson proved it existed, in 1897, but another man gave it the name 'electron'.
The model views electrons as holding indeterminate positions in a diffuse cloud around the nucleus of the atom.
The uncertainty principle means a person cannot know an electron's position and energy level at the same time. These potential states form a cloud around the atom. The potential states of electrons in a single atom form a single, uniform cloud.
Chile
Chile (officially called Republic of Chile) is a country on the south-western side of South America. Most people there speak Spanish.
Chile, which claims a part of the Antarctic continent, is the longest country on earth. The Atacama Desert, in the north of the country, is the driest place on earth. The average rainfall there is less than per year. The center of Chile, with the two cities Santiago and Valparaíso, has a Mediterranean climate with an average temperatures of in January and in July. In the middle of Chile, the country is very good for growing things.
There are about 16.9 million people living in Chile in 2009. About 10 million people live in the center of Chile around Valparaíso and Santiago, on about 20% of the total land.
Chile is a well-educated country. Only 2.7% are not able to read or write. Some believe that Chile has one of the best school systems in South America.
About 95% of Chileans are people with a combination of European descent, mostly Spanish, but also German, English, Italian and Arab people. Around 2% of the population is Native American, but most people have native ancestors. Immigrants are 7% of the population. including Peruvians, Bolivians, Colombians, Haitians, Chinese and Europeans. The majority of people are Roman Catholic (62.8%), but many do not go to church. About 10% are Protestant, and there are some Jews and Muslims as well. The country's official language is Spanish. Chili peppers, first cultivated by Native Americans from other Latin American countries and the United States, did not come from this country, although it has a similar name.
Chile's currency is the Chilean "peso".
Chile borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far south. It is over north to south, but only at its widest point east to west.
The northern Atacama Desert has great mineral wealth, mostly copper and nitrates. Chile is the largest producer of copper. The Andes Mountains are on the eastern border.
Chile controls Easter Island and Sala y Gómez Island, the easternmost islands of Polynesia.
Only a few of the many distinctive South American animals are found in Chile. Among the larger mammals are the puma or cougar, the llama-like guanaco and the fox-like chilla. In the forest region, several types of marsupials and a small deer known as the pudu are found.
There are many species of small birds, but not most of the larger common Latin American types. Few freshwater fish are from Chile, but North American trout have been successfully introduced into the Andean lakes. The coast of Chile is close to the Humboldt Current, so ocean waters have many fish and other forms of marine life. This in turn supports a rich variety of waterfowl, including several penguins. There are many whales, and six species of seals in the area.