Group 2

Question 1

Explain why the second ionisation energy of calcium is lower than the second ionisation energy of potassium.

Answer 1

In Ca(+) (outer) electron(s) is further from nucleus
Or Ca(+) loses electron from a higher (energy) orbital
Or Ca(+) loses electron from a 4(s) orbital or 4th energy level or 4th energy shell and K(+) loses electron from a 3(p) orbital or 3rd energy level or 3rd energy shell

Question 2

Identify the s-block metal that has the highest first ionisation energy.

Answer 2

Be /Beryllium

Question 3

Give the formula of the hydroxide of the element in Group 2, from Mg to Ba, that is least soluble in water.

Answer 3

Mg(OH)2

Question 4

A time of flight (TOF) mass spectrum was obtained for a sample of barium that contains the isotopes 136Ba, 137Ba and 138Ba
The sample of barium was ionised by electron impact.
Identify the ion with the longest time of flight.

Answer 4

138Ba+