What would you expect the combining ratio to be for alkali metals to be with a halogen? With oxygen?

Mar 10, 2017

The combining ratio for alkali metals and halogens is $1 : 1$.

The combining ratio for alkali metals and oxygen is $2 : 1$.

Explanation:

Alkali metals form ${1}^{+}$ ions. Halogens form ${1}^{-}$ ions. Oxygen forms ${2}^{-}$ ions.

Ionic compounds are neutral, so the total positive charge has to equal the total negative charge.

Alkali metals plus halogens: potassium and chlorine

${\text{K"^+ + "Cl}}^{-}$$\rightarrow$$\text{KCl}$

The combining ratio for alkali metals and halogens is $1 : 1$.

Alkali metals plus oxygen: potassium and oxygen

${\text{2K"^+ + "O}}^{- 2}$$\rightarrow$$\text{K"_2"O}$

The combining ratio for alkali metals and oxygen is $2 : 1$.

Mar 10, 2017