2 - Group 2, the alkaline earth metals

Question 1

In order, what are the group 2 elements?

Answer 1

Be, Mg, Ca, Sr, Ba, Ra

Question 2

Are group 2 metals oxidised or reduced?

Answer 2

Oxidised as they lose electrons when they react

Oxidation state 0 → +2

Question 3

What is the general trend in atomic radius down group 2?

Answer 3

Atomic radius increases

Question 4

Why does atomic radius increase down group 2?

Answer 4

Down the group, the atoms have more shells of electrons making the atom bigger

Question 5

What is the general trend in 1st ionisation energy down group 2?

Answer 5

1st IE decreases down group 2

Question 6

Why do 1st ionisation energies decrease down group 2?

Answer 6

• Weaker forces of attraction between nucleus and outermost electrons
• Shielding increases so larger distance between outer electron and nucleus

Question 7

What is the general trend in melting points down group 2?

Answer 7

Melting point decreases

Question 8

Why do melting points decrease down group 2?

Answer 8

• Metallic bonding weakens as atomic size increases
• Distance between positive ions and delocalised electrons increases so electrostatic forces between them weaken

Question 9

Why does Mg have a lower melting point than Ca?

Answer 9

Mg’s crystal structure changes

Question 10

What is the trend in reactivity down group 2?

Answer 10

Reactivity increases

Question 11

Going down the group, why are group 2 elements more reactive?

Answer 11

Outer electrons are easier to lose
- Due to increase in atomic radii and shielding

Question 12

When group 2 elements are reacted with oxygen, what is formed?

Answer 12

Metal oxides

Question 13

When group 2 elements are reacted with water, what is formed?

Answer 13

Metal hydroxide & hydrogen

Question 14

What is the general equation for when group 2 elements react with water?

Answer 14

M + 2H₂O → M(OH)₂ + H₂

Question 15

State the equation of the reaction between magnesium and steam and state what is produced

Answer 15

Mg _(s) + H₂O _(g) → MgO _(s) + H_{2 (g)}
- Solid white powder of MgO produced

Question 16

State the equation of the reaction between magnesium and water and state what is produced

Answer 16

Mg _(s) + 2H₂O _(l) → Mg(OH)_{2 (s)} + H_{2 (g)}
- Sodium hydroxide is formed as a solid as it is insoluble

Question 17

State the equation of the reaction between calcium and water and state what is produced

Answer 17

Ca _(s) + 2H₂O _(l) → Ca(OH)_{2 (aq)} + H_{2 (g)}
- Aqueous calcium hydroxide is formed

Question 18

What would be observed when group 2 metals react with water?

Answer 18

• Fizzing, more vigorous down group
• Metal dissolving, faster down group
• The solution heating up, hotter down group