Group 2 Elements and Periodicity

Question 1

What happens to first ionisation energy as the elements in group 2 go down. Why does this happen?

Answer 1

Ionisation energy decreases. This happens because:
Atomic radius decreases
The number of protons increase
Outer electrons get further from the nucleus
Electron Shielding Increases
Outer electrons are less attracted to the nucleus
Electrons held less tightly so first ionisation energy decreases.

Question 2

What happens to reactivity as the elements in group 2 go down. Why does this happen?

Answer 2

Reactivity increases down the group. This happens because:
Despite there being an increase in protons
There are more shells
And the outer electrons are further from the nucleus
So Outer Electrons are less attracted to the nucleus.

Question 3

When group 2 metals react, what does the substance formed look like.

Answer 3

A white solid.

Question 4

Group 2 Metal + Water —-> ________ + ________

Answer 4

Group 2 Metal + Water —-> Metal Hydroxide + Hydrogen

Question 5

What can be observed when a group 2 metal reacts with water?

Answer 5

The solid metal would dissolve and there would be fizzing from the hydrogen.

Question 6

What happens to the reactions of group 2 metals as we go down the elements?

Answer 6

The reactions become more vigorous.

Question 7

Group 2 Metal + Acid —-> ________ + ________

Answer 7

Group 2 Metal + Acid —-> Salt + Hydrogen

Question 8

Group 2 Oxide + Acid —-> ________ + ________

Answer 8

Group 2 Oxide + Acid —-> Salt + Water

Question 9

Group 2 Hydroxide + Acid —-> ________ + ________

Answer 9

Group 2 Hydroxide + Acid —-> Salt + Water

Question 10

Group 2 Oxide + Water —-> ________ + ________

Answer 10

Group 2 Oxide + Water —-> Metal Hydroxide

Question 11

Group 2 Hydroxide + Water —-> ________ + ________

Answer 11

Group 2 Hydroxide + Water —-> Metal Ion + Hydroxide

Question 12

What happens to solubility as the hydroxides in group 2 go down. What happens to the pH and why?

Answer 12

Solubility of Hydroxides Increases as we go down the group. The pH of the solution made becomes more alkali as it releases more OH⁻ ions.

Question 13

How can we test for sulphate ions?

Answer 13

By dropping barium ions into the solution. If the solution contains sulphate ions, there will be an insoluble white precipitate.

Question 14

What does PEAS stand for?

Answer 14

Protons
Electrons
Attractions
Shielding

Question 15

What is the definition of Ionisation Energy?

Answer 15

The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms.

Question 16

What factors can affect ionisation energy?

Answer 16

Nuclear Charge
Distance between nucleus and outer shell.
Shielding
Attractions

Question 17

What’s the trend of ionisation energy down groups? Why does this happen?

Answer 17

Ionisation energy decreases down a group. This happens because:
Despite there being greater nuclear charge.
The outer electrons are further from the nucleus.
There is more shielding.
So the attractions between the nucleus and the outer electrons are weaker.

Question 18

What’s the trend of ionisation energy across periods? Why does this happen?

Answer 18

Ionisation energy increases periods. This happens because:
The radius decreases
The amount of protons increase.
There is no change in shielding
So outer electrons fill the same energy level
causing attractions stronger attractions.

Question 19

What’s the equation for the 3rd ionisation energy for Aluminium?

Answer 19

Al²⁺₍𝓰₎ —> Al³⁺₍𝓰₎ + e⁻

Question 20

What happens to ionisation energy when it jumps from one shell to another?

Answer 20

It will usually change dramatically.