Lesson 1, Topic 1
In Progress

Describe the build-up of electrons in ‘shells’ and understand the significance of the noble gas electronic structures and of the outer shell electrons.

(The ideas of the distribution of electrons in s and p orbitals and in d block elements are not required.)

In the centre of an atom lies the nucleus. The nucleus contains the protons and neutrons of the atom. Around the nucleus are multiple shells. These shells contain the electrons of the atom.

The shells can have the following distribution of electrons

  1. 2 electrons
  2. 8 electrons
  3. 8 electrons

Not all elements will have 3 shells of electrons. For example, Lithium has an electron number of 3. Thus it has 2 electrons in its first shell and 1 electron in its second shell.

When two atoms react with each other, their goal is to have either a full outer shell of 8 electrons or an empty outer shell with 0 electrons.

For example, Lithium has an electron number of three. It would lose 1 electron to stabilize during a reaction rather than gaining 7 electrons.