General Atomic Chemistry
The AtomThe atom is made up of two parts, the nucleus and the electrons.
The nucleus is on the inside and consists of protons, p+ and neutrons, n. Protons have a positive charge each, which would cause the protons to repel eachother, which is why there are neutrons to shield the protons from eachother.
The electrons have a negative charge and occupy a certain shell, as shown to the right.
The drawing on the right is called the Bohr Model of an atom. It is a simplified version of the real sturcture, but it is exact enough for our purposes.
Isotopes
Isotopes are atoms with the same number of protons and electrons in their structure, but with a different number of neutrons. This means that isotopes are chemically almost identical, only their mass is different. The atom shown on the left is a Helium-4 atom, which means it has two protons and two neutrons. An isotope of Helium-4 is Helium-3, which has only one neutron.
