Atomic Theory
Learn all you should know about the Atomic Theory, an important topic in chemistry.
nucleus
Orbitals, paths or shells on
which the electrons rotate
At the center of the atom, there is the nucleus. This contains the neutrons and the protons. Surrounding the nucleus, there are elliptical paths or shells or orbits on which the electrons rotate. It is the electrons, which can move. The protons and the neutrons do not move.
Mass and charge of the three small particles making an atom
|
Particle |
Mass |
Charge |
|
Proton |
1 |
+1 |
|
Neutron |
1 |
No charge |
|
Electron |
Negligible mass = 0 |
-1 |
ATOMIC NUMBER
In a neutral atom of an element, there is an equal number of protons and electrons. This number is called the ATOMIC NUMBER OF THE ATOM.
A hydrogen atom is the simplest atom, containing one proton and one electron. Its atomic number is therefore 1.
Atoms of different elements all have different numbers of protons and electrons, that is, they all have different atomic numbers.
ELECTRONIC CONFIGURATION
The electronic configuration of an element describes the way in which the electrons of that element are arranged in the different shells surrounding one atom of it.
The orbitals of an atom are numbered 1, 2, 3, 4 etc… outwardly from the nucleus.
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