Fundamental particles & Sub shell Theory
An atom is the basis of matter. It is made up of three distinct parts; the protons, neutrons and electrons. The diagram below shows a diagram of a carbon atom that you should all be familiar with.
The protons and neutrons are concentrated in the nucleus at the center of the atom. This gives the nucleus a positive charge. The electrons spinning around the outside have negative charge. The negative charges and the positive charge match up in order to make the atom stable.
- The relative charge of a proton is +1.
- The relative charge of an electron is -1.
- The relative charge of a neutron is 0.
The relative masses of protons and neutrons is 1. The relative mass of an electron is 0.0005. An electron is considerably smaller than a proton or neutron, but is the electron which allows bonding to other atoms to take place.
From GSCE Chemistry, you may remember that electrons fill up shells. The first shell takes 2 electrons and the next can take 8 electrons. If the outer shell isn’t full, an atom can bind with another atom in order to make itself stable. We are going to expand on that theory.
The shells are split into smaller parts known as sub shells. The sub shells are known as S, P, D & F. Within these sub shells are orbitals. Orbitals are small clouds where there is a 95% chance of finding an electron. In each sub shell there are a certain number of orbitals and can contain a certain amount of electrons.
- S can 2 electrons and 1 Orbital.
- P has 6 electrons and 3 Orbitals.
- D has 10 electrons and 5 Orbitals.
- F has 14 electrons and 7 Orbitals.
The rules from GCSE still apply. The first shell can only contain 2 electrons so only has a S orbital. Taking Helium for instance, see the diagram below, it’s electronic configuration would be written as 1S2. 1 is the main energy level as it is in the first shell, s is the letter of the sub shell and 2 is the number of electrons.
Lithium’s configuration would be 1s2, 2s1. It has it’s first shell fun and it’s second shell has one electron in. After the 2s sub shell is full, we only have 2 electrons in the shell as a whole, so we need to fill the rest of the shell before moving on to the the third shell. This is where we fill up the P sub shell. Carbon’s configuration would therefore be 1s2, 2s2, 2p2. And we can go on until we reach higher configurations like Silicon’s 1s2 2s2 2p6 3s2 3p4.