Chemical formulae of elements

A chemical formula is used to represent an element or compound in balanced chemical equations.

The formula for most elements is just its chemical symbol. For example:

  • helium, He
  • lithium, Li
  • beryllium, Be
  • boron, B
  • carbon, C
  • neon, Ne
  • sodium, Na
  • magnesium, Mg
curriculum-key-fact
It's important to use the names and chemical symbols for the first 20 elements in the periodic table, as well as the elements in groups 1 and 7.

Some non-metal elements exist as molecules that are made up of two atoms joined together. The formulae of these elements are the element's symbol followed by a subscripted '2'. For example:

  • iodine, I2
  • bromine, Br2
  • chlorine, Cl2
  • fluorine, F2
  • oxygen, O2
  • nitrogen, N2
  • hydrogen, H2

A mnemonic can be used to remember these elements:

IBring Clay For Our New House.

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It's important to remember which elements exist as molecules, and which do not. Take care to use the correct form in chemical equations involving these elements.
Question

What are the chemical formulae of the elements neon, nitrogen and sodium?

  • Ne
  • N2
  • Na