reactivity trends Flashcards
Why are group 2 metals also known as alkaline earth metals?
Group 2 metals have alkaline properties and are found in stable compounds such as CaCo3
Why are group 2 elements reducing agents?
Group 2 elements contains two electrons on their outer shell which can be donated to another atom which will oxidised the group 2 metal and reduce the atom it donated electrons too.
[Remember OILRIG, oxidation is loss, reduction is gain of electrons]
What happens when a group 2 element reacts with oxygen?
When a group 2 element reacts with oxygen it forms a metal oxide.
What is the reaction between Mg and O2? Show the redox reactions that occur in the reaction.
Mg (s) + O2 (g) –> 2MgO (s)
0 0 +2 -2
Mg goes from 0 to +2 and is therefore oxidised
O goes from 0 to -2 and is therefore reduced
What happens when group two elements react with water?
Will form a metal hydroxide and hydrogen gas.
General formulae of M(OH)2 (M stands for the metal)
What happens to the reactivity of Group 2 metals and water as you go down the group and why?
Group 2 metals will react more vigour-sly with H2O as you go down the group as reacitivty increases down the group.
The outer shell electrons are further away from the nucleus + additional electron shielding means it is easier to loose.
What happens when a Group 2 metal reacts with dilute acids?
Will form Salt and H2O.
Similarly redox occurs and reactivity with acids increase down the group with similar reason to reactivity with H2O.
What happens when Group 2 oxides react with water?
Group two compounds will react with H2O to release OH- ions and form a metal hydroxide.
What happens to the solubility and PH of Group 2 hydroxides as you go down the group and how can you show this trend?
The solubility of group 2 hydroxides will increase down the group and will increase the PH.
You can easily test this by reacting a group 2 hydroxide in H2O and measuring the PH of each solution.
