3.1.2 Group 2 Flashcards
1
Q
What is the electron configuration of the outer shell of group 2 elements?
A
s2
2
Q
How do group 2 elements form ions?
A
- Lose 2 electrons
- Form 2+ ions
3
Q
How does reactivity change as you go down the group?
A
- Reactivity increases as you go down the group
- Atom gets larger as atomic radius increases
- Electron shielding increases due to additional shells
- Electrons are lost more easily
4
Q
How do group 2 elements react with water?
A
- Form metal hydroxides and hydrogen gas
- Reaction becomes more vigorous as you go down the group
e.g. Mg + 2H2O -> Mg(OH)2 + H2
5
Q
What happens when magnesium reacts with steam?
A
- Form magnesium oxide
- Reaction is faster than with cold water as particles have more kinetic energy
Mg + H2O -> MgO + H2
6
Q
How do group 2 elements react with oxygen?
A
- Form metal oxides, which are often white solids
- Strontium and barium react in excess oxygen and heat to form metal peroxides
e.g. 2Mg + O2 -> 2MgO
e.g. Sr + O2 -> SrO2
7
Q
How do group 2 elements react with dilute acids?
A
- Form a salt and hydrogen gas
e.g. Mg + 2HCl -> MgCl2 + H2
e.g. Ca + H2SO4 -> CaSO4 + H2
e.g. Mg + 2HNO3 -> Mg(NO3)2 + H2
8
Q
How do the first and second ionisation energies change as you go down the group?
A
- Decreases down the group
- More shielding and atomic radius increases
- Weaker attraction between the nucleus and outer electrons
- Less energy is needed to remove outer electrons
9
Q
How do group 2 oxides react with water?
A
- Form alkaline solution of the metal hydroxide
10
Q
How does the solubility of the group 2 hydroxides change down the group?
A
- Solubility increases
- Alkalinity increases as there are more OH- (aq) ions
11
Q
How are group 2 compounds used in agriculture?
A
- Calcium hydroxide is used to neutralise acidic soils
Ca(OH)2 (s) + 2H+ (aq) -> Ca2+ (aq) + 2H2O (l)
12
Q
How are group 2 compounds used in medicine?
A
- Magnesium hydroxide and calcium carbonate are used at antacids
- Treats indigestion by neutralising stomach acid
Mg(OH)2 (s) + 2HCl (aq) -> MgCl2 (aq) + 2H2O (l)
CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O (l) + CO2 (g)
