Group 2 Flashcards
What are group 2 elements also known as?
Alkaline earth metals
What is the redox half equation for how group 2 metals react?
M-> M2+ + 2e-
What colours are group 2 compounds and solutions?
Compounds- White
Solutions- colourless
What are the properties of group 2 metals?
Light low densities
High melting points
What is the trend in reactivity down group 2 and why?
Increases in reactivity-
Strength of metallic bond decreases as more shielding and outer electron is further away so it is easier to loose the 2 electrons
What happens to the group 2 elements oxidation number in a redox reaction and what does this mean?
Oxidation number increases so is oxidised and acts as the reducing agent
How does a group 2 element react with oxygen-
What is formed?
And give the half equations and oxidation numbers-
2M+O2 -> 2MO
OXIDES ARE FORMED
2M-> M2+ + 2e-
O2 + 4e- -> 2O2-
M(0) -> M(+2) oxidised
O2(0) -> O2 (-2) reduced
How does Mg react with water-
What is formed? And why is this different to other group 2 elements?
Mg + H2O -> MgO + H2
Mg is the least reactive so only reacts with steam rapidly
How does a group 2 element react with water-
What is formed?
And give the half equations and oxidation numbers-
How does the solubility of the product change?
M + 2H2O -> M(OH)2 +H2
ALKALINE METAL HYDROXIDES - increased solubility as you go down group
M-> M2+ + 2e-
2H+ + 2e- -> H2
M(0) -> M(+2) oxidised
H(+1) -> H(0) reduced
How does a group 2 element react with a dilute acid-
What is formed?
And give the half equations and oxidation numbers-
M+ H2SO4 -> MSO4 + H2
M+ 2HCl -> MCl2+ H2
M+ 2HNO3 -> M(NO3)2 + H2
M-> M2+ + 2e-
2H+ + 2e- -> H2
M(O) -> M(2+) oxidised
H(+1) -> M(0) reduced
What is the reaction of a group 2 oxide with water?
MO+ H2O -> M(OH)2
What trends do you see as you go down the group 2 hydroxides?
Increasing solubility
Increase in pH (OH- ions)
Increase in alkalinity
What is Ca(OH)2 used for?
Neutralise acidic soils
What group 2 compounds neutralise stomach acid?
Mg(OH)2
CaCO3
