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The Periodic Table

The Alkali Metals  -  Reaction with Water.

Lithium, sodium and potassium all react with cold water,
forming a soluble alkaline hydroxide and hydrogen gas.

lithium + water     lithium hydroxide   +   hydrogen.
2Li_(s) + 2H₂O_(l)            2LiOH_(aq)      +        H_2(g)

sodium + water     sodium hydroxide   +   hydrogen.
2Na_(s) + 2H₂O_(l)            2NaOH_(aq)      +        H_2(g)

potassium + water     potassium hydroxide + hydrogen.
2K_(s) + 2H₂O_(l)            2KOH_(aq)      +        H_2(g)

Note the (aq) after the hydroxide, showing it is dissolved in water.
Hydrogen is given off as a gas. You must know how to test for hydrogen gas.

All three metals float on water.

Sodium melts and forms a ball
which fizzes over the surface of the water as it gives off hydrogen.

Lithium is less reactive and does not melt but does give off hydrogen.

Potassium is the most reactive. It melts, reacts vigorously
and burns with a lilac flame as it gives off hydrogen.

All the hydroxides are strongly alkaline and dissolve in the water.

The alkali metals are so named because they form
alkaline oxides and hydroxides.
The metals themselves are not alkaline, they are just metals (neutral).

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