Down the alkaline earths

Science · Chemistry · ages 16-17

Name ______________________ Date ____________

Calcium plus water gives...
- Calcium oxide plus oxygen
- Nothing at room temperature
- Calcium hydroxide plus hydrogen
Reactions of group 2 metals with water down the group get...
- Slower and slower
- More and more vigorous
- Exactly the same
Hydroxides grow less soluble down group 2.
Circle one: True False
Sulfate solubility down the group...
- Stays flat
- Rises steeply
- Falls, so barium sulfate barely dissolves
Why does reactivity rise down the group?
- More protons pull harder
- Outer electrons sit further out with more shielding, so ionisation energy falls
- Atoms gain extra neutrons
Calcium oxide plus water gives...
- Calcium hydroxide
- Calcium plus oxygen
- Calcium sulfate
Why does milk of magnesia soothe indigestion?
- It coats the stomach with sulfate
- Magnesium hydroxide neutralises excess stomach acid
- It adds more acid to balance
Why can barium sulfate be swallowed for a scan when barium ions are toxic?
- Stomach acid destroys all barium
- It turns into calcium inside the body
- It is so insoluble that it passes through unabsorbed

Answer key

For grown-ups. Fold this page away before handing over the rest.

Calcium hydroxide plus hydrogen · Metal plus water gives hydroxide plus hydrogen.
More and more vigorous · Falling ionisation energy speeds each lower metal up.
False · They grow more soluble; the sulfates are the ones that fade.
Falls, so barium sulfate barely dissolves · Sulfates run opposite to the hydroxides.
Outer electrons sit further out with more shielding, so ionisation energy falls · Loosely held outer electrons leave with less fuss.
Calcium hydroxide · Oxides give the same hydroxide as their metals.
Magnesium hydroxide neutralises excess stomach acid · A soluble-enough base meets the excess acid.
It is so insoluble that it passes through unabsorbed · What never dissolves can never reach the blood.