Group 2 Metals ( AS )

Question 1

Write an equation for the first ionisation energy of magnesium

Answer 1

Mg(g)—>Mg+(g)+e-

Question 2

Explain the trend in the ionisation energy across peroid 3?

Answer 2

First ionisation energy increases across group 3 because of increased nuclear charge, decreased atomic radius with similar shielding, this means more energy is required to remove the first electron.
●Dips at Al because: outer electron is in a 3p orbital, higher energy than 3s orbital—> less energy needed to remove electron
●Dips at S because one 3p orbital contains a pair of electrons—> repulsion between paired electrons—> less energy needed to remove that electron

Question 3

What happens to the first ionisation energy as you go down group 2? Why?

Answer 3

Decreases because: number of filled electron shells increases down the group—> increased shielding, increased atomic radius—> weaker attraction between outer electron and nucleus—> less energy required to remove the electron

Question 4

How does reactivity with water change as you go down group 2?

Answer 4

increases( Mg least -> Ba most)
Because outer electrons are further away from the nucleus and more shielding so electrons are lost easily

Question 5

write an equation for the reaction between barium and water

Answer 5

Ba(s) + 2H20(l) -> Ba(OH)2(aq) + H2

Question 6

what is the trend in hydroxide solubility down group 2?

Answer 6

increases down the group

Question 7

what is the trend in sulphate solubility down group 2?

Answer 7

decreases down the group

Question 8

what is the trend in melting point down group 2?

Answer 8

melting point decreases
The sea of delocalised electrons is further away from the positive nucleus
weaker metallic bonds

Question 9

what happens to the atomic radius as you go down group 2?

Answer 9

atomic radius increases
there’s more occupied electron shells

Question 10

what’s used to reduce Titanium from Titanium chloride?

Answer 10

Magnesium

Question 11

whats the equation for the extraction of Titanium from Titanium chloride using Magnesium?

Answer 11

1) TiO2 + 2Cl2 + C —> TiCl4 + CO2
2) TiCl4 + 2Mg —> Ti + 2MgCl2

Question 12

what are flue gases?

Answer 12

gases which are given off by power stations are harmful to the environment

Question 13

what is used to remove flue gases?

Answer 13

Calcium Oxide ( CaO ) or Calcium Carbonate ( CaCO3 )

Question 14

whats the equation for flue gas desulfurisation?

Answer 14

CaO + SO2 —> CaSO3
CaCO3 + SO2 —> CaSO3 + CO2

Question 15

what is calcium hydroxide ( Ca(OH)2 ) used for?

Answer 15

used to neutralise soil pH which is acidic

Question 16

what is magnesium hydroxide ( Mg(OH)2 ) used for?

Answer 16

Milk of magnesia- antacid to treat indigestion

Question 17

what is the use of barium sulphate( BaSO4 ) ? why is it safe?

Answer 17

used in barium meals to outline the gut in X-Rays
Ba2+ is toxic but it is fine as barium sulphate is insoluble

Question 18

what is used to test for the presence of sulphate ions?

Answer 18

Barium Chloride ( BaCl2 )

Question 19

How can barium chloride be used to test for the presence of sulphate ions?

Answer 19

first add your sample to HCl to acidify the solution and then add BaCl2 if sulphate ions are present a white precipitate of BaSO4 will form
Ba2+ + SO4^2- —> BaSO4