Periodic table

Atoms in the same group have similar properties

atoms in the same period have the same number of shells

\ Metals

when metals react they lose electrons and have a positive charge

metals are: malleable, sonorous, good conductors, strong (metallic bonds)

\ Alkali metals - group 1

soft, reactive

become more reactive as you go down, lower boiling points as you go down

\ The reactivity of group 1 elements increases as you go down the group because the atoms become larger, which means that the outer electron becomes further from the nucleus.

This in turn means that the electrostatic attraction between the positive nucleus and the outer negative electron decreases in strength. 

As a result the outer electron will be lost more easily, and so the element will be more reactive. 

Alkali metal + water ➔ metal hydroxide + hydrogen

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1. Lithium reacts with oxygen to form lithium oxide, Li2O.
2. Sodium reacts with oxygen to form sodium oxide, Na2O or sodium peroxide, Na2O2. 
3. Potassium reacts with oxygen to form potassium peroxide, K2O2, or potassium superoxide, KO2.

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