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Atomic Radii
Atomic Radius half the distance between the nulei of two atoms joined by a covalent bond
Factors such as
-
nulear charge
-
screening effect
-
number of energy levels
affect atomic radius.
Atomic radius increases down the group (screening effect)
Atomic radius decreases across the period (increased nuclear charge)
Ionisation Energy
Ionisation Energy the energy required to remove the most loosely bound electron from an atom at its ground state
E.g. Na 2 8 1 >>> Na+ 2 8
When an atom becomes stabilised (full outer shell) the energy rapidly heightens.
Ionisation energy increases across the period (increased nuclear charge)
Ionisation energy decreases down the group (screening effect and increased atomic radius)
Exceptions to Ionisation Energy Rules
- Nitrogen (1400) and Oxygen (1310) – Nitrogen has a half full outer shell which is more stable than that of oxygen
- Berillium (900) and Boron (799) – Berillium has a full outer shell which is more stable than that of boron
