C1 Particles

The particulate nature of matter

atom = the smallest unit of matter; the smallest unit of a chemical element, consists of a nucleus, which has a positive charge, and a set of electrons that move around the nucleus

molecule = the smallest particle in a chemical element or compound that has the chemical properties of that element or compound, are made up of atoms that are held together by chemical bonds

Physical and chemical changes

a physical change - doesn't change what the substance is

CAN BE REVERSED (moved backwards)

a chemical change - where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed

CANNOT BE REVERSED (moved backwards)

Elements, compounds and mixtures

An element is a substance that is made entirely from one type of atom. For example, the element hydrogen is made from atoms containing a single proton and a single electron. If you change the number of protons an atom has, you change the type of element it is. The simplest form of an element is a molecule.

Compounds are chemicals


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