How do you calculate the number of valence electrons in a molecule?

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How do you calculate the number of valence electrons in a molecule?

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Answer 1 · 2014-12-21T13:26:15

The number of valence electrons for molecules can be calculated by adding the valence electrons of all the atoms that form that respective molecule.

Here are some examples

$C O_{2}$ $CO_2$ : Each carbon dioxide molecule is formed from 1 C atom and 2 O atoms. We know that C has 4 valence electrons and that O has 6 valence electrons, which means that the number of valence electrons for 1 $C O_{2}$ $CO_2$ molecule will be

$1 \cdot 4 + 2 \cdot 6 = 16 e^{-}$ $1 * 4 + 2 * 6 = 16e^-$

$H_{2} O$ $H_2O$ : Again, each water molecule is formed from 1 O atom and 2 H atoms. Since the number of valence electrons for O and H are 6 and 1, respectively, one molecule of water will have

$2 \cdot 1 + 1 \cdot 6 = 8$ $2 * 1 + 1 * 6 = 8$ valence electroncs.

$H_{2} S O_{4}$ $H_2SO_4$ : One molecule of sulfuric acid has 2 H atoms, 1 S atom, and 4 O atoms, each contributing 1, 6, and 6 valence electrons. So the number of valence electrons for 1 molecule of sulfuric acid is

$2 \cdot 1 + 1 \cdot 6 + 4 \cdot 6 = 32 e^{-}$ $2 * 1 + 1 * 6 + 4 * 6 = 32e^-$ .

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How do you calculate the number of valence electrons in a molecule?

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