2.2 Group 2 metals Flashcards
Describe and explain the trend in atomic radius down the group
Atomic radius increases down group 2 due to additional electron shells.
Describe the trend in reactivity down group 2
Reactivity increases down group 2.
Explain the trend in reactivity
There is increased electron shielding down the group and a weaker attraction between the nucleus and outer electrons, making the outer electrons easier to use.
Describe the trend in first ionisation energy
First ionisation energy decreases down the group.
Explain the trend in first ionisation energy
Greater distance between nucleus and electron being removed due to a larger atomic radius (down the group) so weaker attraction and increased amounts of shielding so less energy required to remove it.
Describe the trend in melting point
Melting point decreases down the group.
Explain the trend in melting point
- Group 2 elements are metallic
- Size of the metal ion increases down the group, so weaker attraction between metal ions and delocalised electrons in the metallic bond as they act over a greater distance
- Means less energy is required to overcome the forces
Describe the reaction of group 2 metals with water
React with water to produce a metal hydroxide and hydrogen.
Describe the reaction between magnesium and water, and give the equation
- Magnesium reacts very slowly with liquid water
- Mg + 2H2O => Mg(OH)2 + H2
Describe the reaction between magnesium and steam, and give an equation
- Magnesium reacts much quicker than with liquid water as there is extra energy
- Magnesium burns with a bright white flame to form hydrogen and magnesium oxide, a white powder
- Mg + H2O => MgO + H2
Describe the trend in solubility of the group 2 hydroxides
- The solubility increases down the group
- Magnesium hydroxide (Mg(OH)2) is insoluble
- Calcium hydroxide (Ca(OH)2) is partly soluble
- Strontium hydroxide (Sr(OH)2) is soluble
- Barium hydroxide (Ba(OH)2) is soluble
What is a medical use of magnesium hydroxide (Mg(OH)2)
It can be used as an antacid (milk of magnesia) as it neutralises stomach acid.
Describe the trend in the solubility of group 2 sulfates
- Solubility decreases down the group
- Magnesium sulfate (MgSO4) is soluble
- Calcium sulfate (CaSO4) is insoluble
- Strontium sulfate (SrSO4) is insoluble
- Barium sulfate (BaSO4) is insoluble
What is a medical use of Barium sulfate (BaSO4) and why is this possible
- Can be used as barium meals which are a form of medical tracer that allow internal tissues and organs to be imaged
- Barium sulfate is toxic if it enters the bloodstream, however because it is insoluble it cannot be absorbed into the blood so it is safe to use
