10 element symbols and charges worth memorising

Chemistry is 8 scored questions. A handful of symbols carries most of them.

You will not be asked to recite the periodic table, but you will be asked to read a formula. These are the symbols and charges the TEAS reuses.

1 Na⁺ sodiumthe main extracellular cation. Latin natrium, which is why it is not S.

2 K⁺ potassiumthe main intracellular cation. Latin kalium.

3 Ca²⁺ calciumbone, clotting and muscle contraction. Note the 2+ charge.

4 Cl⁻ chloridethe anion that follows sodium.

5 Fe ironLatin ferrum; the centre of haem in haemoglobin.

6 H⁺ hydrogen ionwhat pH measures. More H⁺ means a lower pH.

7 OH⁻ hydroxidewhat a base releases.

8 CO₃²⁻ carbonateand HCO₃⁻ bicarbonate, the body’s buffer.

9 O₂ / CO₂diatomic oxygen and carbon dioxide — the gases every respiratory item uses.

10 N nitrogen78% of air, and the N in every amino acid.

Charges matter as much as symbols: a formula balances only when the charges cancel.

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