Reactivity trends Flashcards
In redox reactions, what do the Group 2 elements do?
They get oxidised to form 2+ ions. They are therefore reducing agents as they reduce another agent
What happens if a Group 2 element reacts with oxygen?
They form a metal oxide. For example magnesium reacts with oxygen to form magnesium oxide with the molecular formula of MgO
What happens when a Group 2 element reacts with water?
It forms a alkaline hydroxide with the general formula M(OH)2
Why does reactivity increase as you go down the group?
As you descend down the group, the size of the element increases. This means that the atomic radius and electron shielding both increase. This then reduces the attraction between the nucleus and the outer electrons which then causes the outer electrons to be lost easily.
What happens when a Group 2 element reacts with a dilute acid?
It forms a salt and hydrogen gas
What are the uses of Group 2 compounds?
Agriculture- used to neutralise acidic soil to produce neutral water Ca(OH)2 is used in this case
Medicine- used to treat indigestion- CaCO3 and Mg(OH)2 are used in this case
What happens when a Group 2 compound reacts with water?
Forms a hydroxide with the general formula M(OH)2
What happens to the solubility of Group 2 compounds as you go down the group?
As you go down the group the solubility of the compound increases. It’s pH also increases which results in the compound being more alkaline.
Why does the boiling point increase as you go go down the halogens?
As you go down the group, the element gets more electrons in its structure. This then results in stronger London Forces which then requires more energy to break the bonds. Therefore the boiling point increases as you need more energy to break these bonds
What happens to the halogens in redox reactions?
They get reduced as they need to gain one more electron in order to have a full outer shell. This then means that they are an oxidising agent as it has oxidised another species.
Why does the reactivity of the halogens decrease as you go down the group?
As you descend down the group, the atomic radius of the element increases. This means that electron shielding increases also as there are more inner shells. This then reduces the nuclear attraction to capture an electron from another species. This then causes the reactivity to decline.
What is a disproportionation reaction?
It is when an element has been both oxidised and reduced.
