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TGM5:
Calcium and water, continued
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Notes on the ‘Think for Yourself’ questions
Calcium has a high melting point. It is an elementary substance.
What structure would you expect it to have?
A giant structure, made from one
type of atom.
What structure does water have?
Small molecules. The hold between
the molecules must be stronger than usual as water exists
in the liquid state at room temperature.
Calcium hydroxide doesn't melt at high temperatures. What
structure is it likely to have?
A giant structure.
Hydrogen is in the gas state at room temperature. It is an
elementary substance. What structure would you expect
it to have?
Small molecules made of one type
of atom.
Notes on the video of calcium in excess water
The calcium sinks initially because it is more dense than
water. It rises again because of bubbles that have formed
around it as a result of the reaction. Students should suggest
that these bubbles are bubbles of hydrogen. The white solid
(calcium hydroxide) appears briefly then disappears because
calcium hydroxide dissolves in water: although calcium hydroxide
has a low solubility there is enough water to dissolve it
all.
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Science Enhancement Programme CD-ROM 2005 |
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user
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