Isotopes Atoms which have the same atomic number but different mass numbers. Chemical Symbol is an abbreviation for compounds and elements either a capital letter or a capital letter followed by a lower case letter. Single symbols represent elements and combination symbols represent compounds. The combination of symbols represents a particular compound. This indicates which elements are in a compound and in what proportion they represent.
All matter is made up of tiny particles.
The Atomic Theory states that All matter is made up of tiny particles called atoms Atoms of one element are the same. When other atoms combine with other atoms they create molecules. No ordinary means can destroy atoms or create atoms. Molecules contain identical atoms, Compounds contain atoms of at least two different elements. Element Tables Links to a Visual Chemistry site.