past paper questions

Question 1

state what is meant by two arrows in the first box, (↑↓)

Answer 1

2 electrons spinning with opposite spins

Question 2

state why the arrows are all pointing in the same direction in the 3p boxes.

Answer 2

3 e- with the same direction of spin

Question 3

explain why iodine and chlorine have many similar chemical reactions

Answer 3

1- there is 7 e- in their outer shell
2- number of electrons govern chemical reactions

Question 4

explain why the first ionisation energy of magnesium is higher than of sodium. (3)

Answer 4

1- Mg has a higher nuclear charge
2- stronger attraction to the e-
3- same level of shielding as they’re in the same quantum shell

Question 5

The difference in rates of reaction of Sr and Ba with water is due to the difference in sum of 1st & 2nd ionisation energy. Discuss this suggestion. (6)

Answer 5

1- Ba has more protons, therefore greater nuclear charge
2- Ba experiences more shielding
3- sum of 1st & 2nd ionisation energy of Ba is lower

4- Ba has a larger atomic radius
5- Ba is more reactive
6- therefore outweighs larger nuclear charge

Question 6

explain the trend in the values of the first ionisation energies for the group containing sulfur. (3)

Answer 6

1- first ionisation energy decrease although num. of protons increases
2- 1+ electron shell further away from nucleus
3- e- experience more shielding

Question 7

explain why the difference between the 2nd & 3rd ionisation energies of Ca is much larger than the difference between the 1st & 2nd ionisation energies. (2)

Answer 7

• 1st & 2nd electron removed from the same sub-shell
• 3rd e- removed from a sub-shell closer to the nucleus

Question 8

the elements zinc & scandium are d-block elements but not transition metals;
discuss this statement with electron configurations. (4)

Answer 8

• both elements have last added e- in subshell
• neither forms stable ion with incomplete d-subshell
• therefore are not transition metals

Zn3+: [Ar] 3d10 -> full d subshell
sc3+: [Ar] -> empty d subshell