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The Language of Chemistry Using chemical formulae
We can use the chemical symbols to construct chemical formulae for the molecules and compounds we have met in the tutorials.
| Image |
Formula |
Notes |
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O2 |
A molecule of oxygen gas has two oxygen atoms chemically joined together. This is shown in the formula by the number 2 as a subscript. |
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N2 |
As with oxygen gas, nitrogen gas is identified by the number 2 as a subscript in the formula. |
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H2O |
Water : When hydrogen appears in a formula it normally appears first (it is incorrect to write OH2 as the formula for water!). |
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CO2 |
Carbon dioxide : The carbon atom is shown first in the formula (as it is in the name). Again, it is incorrect to write O2C as the formula for carbon dioxide! |
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KOH |
Potassium hydroxide: Remember that the hydroxide radical has one bonding arm. |
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CuCO3 |
Copper II carbonate : The carbonate radical has two bonding arms. So does the copper atom, according to the name of the compound. |
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