Group 2 - Alkaline Earth Metals

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Trends In Group 2

Group 2 lose 2 electrons when they react, as they have 2 electrons in the outer shell. When they lose the 2 electrons, they form +2 ions, and have the same electron structure as a noble gas

Atomic radius INCREASES down a group due to the extra electron shells

Ionisation energies DECREASE down the group, this is because they have an extra electron shell than the element above, making the outer electrons further away from the nucleus, making it easier to remove. The extra inner shells shield the outer electrons making it easier to remove

Reactivity INCREASES down a group, this is because elements further down the group can lose electrons quicker (read above), this causes them to react.

Melting points generally DECREASE down a group. The group 2 metals have typical metallic structures with the outer electrons being delocalised. Going down the group, the atoms get bigger, so they have a smaller charge/volume ratio, but the number of delocalised electrons does not change, so they are more spread out. The change at magnesium is due to the structure of magnesium is crystal

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Reactions involving Group 2

Group 2 elements react with water, when they react they form +2 ions (oxidised)

They react with water to form a metal hydroxide M(OH)2 and hydrogen H2

The only group 2 element that does not react with water is Be, then the amount of time taken to react increases down the group

When group 2 metals (excluding Be) react with a hydroxide (OH-), the solubility INCREASES down a group

When group 2 metals (excluding Be) react with a sulfate (SO4 2-) the solubility DECREASES down a group

Group 2 compounds are used toneutralise adicity

Calcium Hydroxide is used in agriuculture to neutralise acid soils

Magnesium Hydroxide is used in indigestion tablets as an antacid

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emma

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they are really good notes and  really helpful

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