Ionisation energy

Question 1

Why do first ionisation energies decrease down a group?

Answer 1

As one goes down a group, the outer electrons are found in shells
further from the nucleus and are more shielded so the attraction of
the nucleus becomes smaller.

Question 2

Why is there a general increase in first ionisation energy across a period?

Answer 2

As one goes across a period the electrons are being added to the same
shell which has the same distance from the nucleus and same shielding
effect. The number of protons increases, however, making the effective attraction of the nucleus greater.

Question 3

Why is there a small drop from Mg to Al?

Answer 3

Al is starting to fill a 3p sub shell, whereas Mg has its outer electrons in the 3s sub shell. The electrons in the 3p subshell are slightly easier to remove because the 3p electrons are higher in energy and are also slightly shielded by the 3s
electrons

Question 4

Why is there a small drop from P to S?

Answer 4

With sulphur there are 4 electrons in the 3p sub shell and the 4th is starting to doubly fill the first 3p orbital. When the second electron is added to a 3p orbital there is a slight repulsion between the two negatively charged electrons which makes the second electron easier to remove.

Question 5

The three main factors that affect the strength of metallic bonding are:

Answer 5

1.Number of protons/ Strength of nuclear attraction.

The more protons the stronger the bond

2.Number of delocalised electrons per atom (the outer shell electrons are
delocalised)

The more delocalised electrons the   stronger the bond

3. Size of ion.The smaller the ion, the stronger the bond.