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The Periodic Table

The Alkaline Earth Metals - Reaction with Oxygen  (burning in air).

Magnesium and calcium will both burn in air.
They are sometimes used in the chemicals in fireworks.

Magnesium burns in air with a brilliant white flame to form magnesium oxide.
Magnesium oxide is a base.
magnesium + oxygen  magnesium oxide.
2Mg_(s)  +    O_2(g)              2MgO_(s)

Calcium burns in air with a red flame to form calcium oxide.
calcium + oxygen  calcium oxide (quicklime).
2Ca_(s)    +      O_2(g)                    2CaO_(s)

Calcium oxide is alkaline.
It reacts with water to form calcium hydroxide (slaked lime)
see also the manufacture and uses of lime.

calcium oxide + water     calcium hydroxide.
CaO_(s)     +   H₂O_(l)           Ca(OH)_2(s)

Although calcium hydroxide is written as solid
it is sparingly soluble in water (it dissolves a little).
The solution is called lime water and is used in the test for carbon dioxide gas.

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