A ==Key Stage 3=====Meaning===An [[atom]] is a very small [[particle ]] made of [[proton]]s, [[neutron]]s and [[electron]]s that can join with others other [[atom]]s to make [[molecule|molecules]]. ===About Atoms in The Dalton Model===: In [[The Dalton Model]] [[atom]]s are shown as [[sphere|ball]] shaped [[particle]]s. This makes it easier to draw [[diagram]]s of [[molecule]]s. ===About Atoms beyond The Dalton Model===: [[Atom]]s are made of three smaller [[particle]]s; the [[proton]], [[neutron]] and [[electron]].: [[Proton]]s and [[neutron]]s are found in the [[nucleus]] at the centre of an [[atom]]. [[Electron]]s are found [[orbiting]] the [[nucleus]] in 'shells'.: In an [[atom]] the number of [[proton]]s is always the same as the number of [[electron]]s.: Different [[atom]]s can have different numbers of [[proton]]s and [[neutron]]s.: The simplest [[atom]] is [[Hydrogen]] which has 1 [[proton]] and 1 [[electron]] and no [[neutron]]s.