(U2) Group 2 Elements And Their Compounds

Question 1

What is an s-block element? (2)

Answer 1

• An element which has an atom with highest energy/outer electron
• in an s-subshell (orbital)

Question 2

What is solubility? (3)

Answer 2

• The maximum mass of solute
• that will dissolve in 100 g of solvent
• at a stated temperature

Question 3

What is a base?

Answer 3

A proton acceptor

Question 4

What is thermal stability?

Answer 4

The ability of a substance to resist the effects of heating

Question 5

What is the trend in thermal stability down group II compounds? (4)

COMPOUNDS!!!

Answer 5

• charge density decreases
• metal cations less able to polarise the C-O, O-H bonds etc
• more energy needed to break the bonds
• resulting in thermal stability increasing

Question 6

What is the flame colour for group II metals:

• magnesium
• calcium
• Strontium
• barium

Answer 6

• Mg = Bright white
• Ca = Brick-red
• Sr = Crimson
• Ba = apple green

Question 7

What are the everyday uses of:

• MgO
• CaCO₃

(commercial products)

Answer 7

• MgO = indigestion remedy
• CaCO₃ = in toothpaste

Question 8

What is the trend in solubility of group II sulphates?

Answer 8

Solubility decreases down the group

Question 9

What is the trend in solubility of group II hydroxides?

Answer 9

Solubility increases down the group

Question 10

What are the industrial uses of CaCO₃ (limestone) (3)

Answer 10

Thermally decomposed to produce CaO:

• used in building materials e.g. cement
• blast furnace, used to produce quicklime (CaO)
• also used to produce slaked lime (Ca(OH)₂)

Question 11

What does calcined mean?

Answer 11

Thermally decomposed

Question 12

What is the trend in electronic configuration down group 2?

Answer 12

• As you move down group 2, the number of shielding electrons increases; more full inner sub shells
• all have 2 outer electrons in their outer subshell

Question 13

What is the trend in atomic radius down group 2?

Answer 13

Increases atomic radius due to filling of inner electron subshells

Question 14

What is the trend in 1st ionisation energy down group 2? (4)

Answer 14

1st ionisation energy decreases due to:

• increased shielding by inner electrons
• greater atomic radius
• less electrostatic attraction between atomic nucleus and outermost electrons
• therefore electrons lost more readily / less energy needed to remove electrons

Question 15

What happens in a reaction between group 2 metals and oxygen? (3)

Answer 15

• exothermic reaction
• metal can emit light with a colour
• metal oxide formed - white solid which is basic

Question 16

What do metal oxides form when
dissolved in water?

Is the reaction endo or exo thermic?

Answer 16

• An alkali
• exothermic (very)

Question 17

What is the trend in solubility of group II oxides down the group?

Answer 17

Solubility increases

Question 18

What are the observations when calcium reacts with liquid water? (5)

Answer 18

• sinks then rises
• disappears
• releases heat
• effervescence
• Colourless solution with a white precipitate (calcium hydroxide - slightly soluble)

Question 19

What are the observations when magnesium reacts with liquid water?

Answer 19

A few bubbles released over a long period of time

Question 20

What are the observations when magnesium reacts with gaseous water? (3)

(STEAM)

Answer 20

• bright white light
• white solid produced
• heat released

Question 21

What are the products of the reaction of a group II metal with dilute acids?

Answer 21

• hydrogen gas
• salt

Question 22

What are the observations of the reaction of a group II metal with dilute acids?

Answer 22

• effervescence
• metal disappears
• heat released

Question 23

What is the trend in the rate of the reaction of a group II metal with dilute acids down the group?

Answer 23

Reaction becomes more vigorous down the group