IUPAC (International Union for Pure and Applied Chemistry) has rules for writing chemical symbols and formulas. They are valid in all languages.
For compounds search in a library Nomenclature of inorganic compounds and Nomenclature of organic compounds, with the text adapted to your language, if necessary.
See the links below.
Chemists use the chemical symbol for each element to write formulas. In the case of sodium chloride, sodium's symbol is Na and chlorine's symbol is Cl. By combining these symbols, NaCl represents the chemical formula for sodium chloride.
To write the formula for barium bromide (BaBr₂) as a chemical equation, you need a reaction. For instance, the reaction between barium chloride (BaCl₂) and sodium bromide (NaBr) would form barium bromide and sodium chloride (NaCl): BaCl₂ + 2NaBr → 2NaCl + BaBr₂.
The chemical formula (not equation) of sodium hydrogen sulfite is NaHSO3.
Free nitrogen is diatomic. Write the formula as: N2.
The correct way to write the chemical name of carbon dioxide is "carbon dioxide" or "CO2".
Chemists use the chemical symbol for each element to write formulas. In the case of sodium chloride, sodium's symbol is Na and chlorine's symbol is Cl. By combining these symbols, NaCl represents the chemical formula for sodium chloride.
The correct chemical symbol of magnesium is Mg.
The chemical formula for Sodium Oxide is Na2O.
Chemicals symbols of elements are writed after the rules of IUPAC; see a list at the link below.
The chemical symbol of helium is He; the chemical symbol of magnesium is Mg.
show two wrong ways to write the symbol of calcium
To write the formula for barium bromide (BaBr₂) as a chemical equation, you need a reaction. For instance, the reaction between barium chloride (BaCl₂) and sodium bromide (NaBr) would form barium bromide and sodium chloride (NaCl): BaCl₂ + 2NaBr → 2NaCl + BaBr₂.
Na2SO4
Pb
The chemical formula (not equation) of sodium hydrogen sulfite is NaHSO3.
sodiumsodiumsodium!(why do we have to write it more than once?
Free nitrogen is diatomic. Write the formula as: N2.