Atoms, Elements and Compounds

Every substance is composed of atoms.
The smallest part of an element that can exist is an atom.
Only one type of atom is contained in an element.
Approximately 100 different elements exist.
The periodic table displays the elements.
Each element's atoms are represented by a different chemical symbol, eg. Ne is neon, Ar is argon, C is carbon, etc.
Most substances are compounds.
Compounds contain two or more different elements which are chemically combined at fixed proportions.
A combination of numbers and symbols called a chemical formula represent compounds.
Chemical formulae are used to indicate the different elements in a compound and the number of each element that exist in one molecule of the compound.
The only ways in which compounds can be separated into their elements are through chemical reactions and electrolysis (chemical decomposition produced by causing an electric current to pass through a liquid or solution containing ions).

Equations

The events that occur in a chemical reaction can be summarised through a word equation or a balanced symbol equation.
On the left hand side of the equation are the reactants, on the right are the products.
The total mass of the products of the equation is the same as that of the reactants as no atoms can be lost or gained.
The products of a chemical reaction are always made from the exact same atoms as the reactants.

	Created by Hannah Berry over 9 years ago

GCSE Chemistry (Atomic structure and the periodic table) Note on Notes: Atoms, Elements, Compounds and Mixtures, created by Hannah Berry on 04/02/2017.

Notes: Atoms, Elements, Compounds and Mixtures