Chemical symbols
All substances are made from tiny particles called The smallest part of an element that can exist.. An atom is the smallest part of an A substance made of one type of atom only. that can exist.
Atoms of each element are represented by their own chemical symbol. A chemical symbol:
- consists of one or two letters
- always starts with a capital letter, with any other letter in lower case
For example the symbol O represents an atom of oxygen, and Na represents an atom of sodium. You must write the chemical symbol of sodium as Na, not as NA, na or nA.
Learn more on atoms, elements and compounds in this podcast.
Listen to the full series on 成人论坛 Sounds.
There are over 100 different elements. The names and symbols of the elements are shown in the periodic table. Elements are arranged into groups with similar properties. Groups are numbered from 1 to 7, then 0.
In the periodic table, metals are on the left of the stepped line, and non-metals are on the right.