1 6 Ionisation Energies First Ionisation Energy LO
- Slides: 7
1. 6 Ionisation Energies First Ionisation Energy LO: I understand what the first ionisation is.
The first ionisation energy of an element is the energy required to remove one electron from every atom in one mole of free atoms. It is measured in k. J mol-1 1 st ionisation energy of magnesium: Mg(g) Mg+(g) + e 1 st ionisation energy of fluorine: F(g) F+(g)
Ionisation Energy and the Periodic Table LO: I understand how 1 st ionisation energy changes throughout the Periodic Table.
Across a period: Ne Ionisation Energy (k. J mol-1) Li Be B C N O F Elements of the 2 nd period In general, the 1 st ionisation energy increases across a period from left to right. The increasing nuclear charge holds the outer electrons more tightly. More energy is needed to remove one outer electron.
Down a group: Ionisation Energy (k. J mol-1) Li Na K Rb Cs Group 1 element The 1 st ionisation energy decreases down a group. There are two factors that decrease the 1 st ionisation energy: • The distance between the nucleus and outer electrons increases. • The shielding effect of the inner electrons.
Second Ionisation Energy LO: I know what the 2 nd ionisation energy is.
The 2 nd ionisation energy is the energy needed to remove a second electron from every atom in one mole of free atoms once a 1 st electron has already been removed. 2 nd ionisation energy of magnesium: Mg+(g) Mg 2+(g) + e 2 nd ionisation energy of fluorine: F+(g) F 2+(g) + e
