Atoms : The Electron
The electron is the smallest particle of the atom.
Electrons are positioned outside the nucleus of
every atom. Electrons remain suspended about the nucleus in what has been
called an electron cloud. Every atom contains a specific number
of electrons dependent on the element.
Discovery
The electron was discovered in 1877 by J.J. Thompson. The elctron was not
seen until the late 19th century when the scanning electron microscope
was developed. Today computer generated images of electrons can be viewed
on the internet.
Size
Electrons are 1/1800 the weight and size of a proton or a neutron. The
electron cloud is 10,000 times larger than the nucleus.
Mass of proton : 1,6726 x 10^(-27) kg
Mass of neutron: 1,6749 x 10^(-27) kg
Mass of electron: 0,00091x10^(-27) kg
Electron Position
Electrons are positioned on the outside of the nucleus
of every atom. Electrons orbit the nucleus in a series of clouds or energy
levels. Atoms have a different number of electrons and energy levels or
orbitals
based on the atomic number or element of the atom.
The maximum number of electrons possible in each
energy level can be determined by the following equation. #E= 2n2
. In this equation, 'n' is the energy level of which you wnat to count
electrons. For example, if you want to know how many electrons can be in
the second energy level of the electron cloud you would substitute the
number 2 for 'n'.
2n2 = 2(22 ) = 2(4)= 8
So, the second level of an electron cloud can have
8 electrons in it.
Some atoms have only one energy level, some have many. The element
Hydrogen has an atomic number of 1. That means that the atom contains only
one electron ansd one energy level. In contrast, the atom radon, with an
atomic number of 86 has 5 energy levels.
Electron Number
The number of electrons in an atom changes.
-
Neutral atoms have the same amount of electrons
as they do protons.
-
Atoms with a postive charge have lost electrons.
-
Atoms with a negative charge have gained electrons.
Neutral atoms have neither a positive nor
a negative charge. They also have the same amount of protons as neutrons.
page created by Paula Jarrett Nasta
last updated 4/27/02