Model of the atom GapFill

All matter is made up of  atomscellsenergyions, which come in different types, called  elementsreactantsparticlesatoms, represented using symbols which can be found on the  compound sequenceInternetreactivity listperiodic table. When these react together,  atomsbeta particlescompoundsmixtures are formed, which have formulae to show the  percentageratioimportanceposition of each element.  MixturesElectronsPure substancesNeutrons contain multiple elements or compounds, and can be  separatedmeltedshapedreacted using filtration, distillation, crystallisation and chromatography.

Over time, different scientists have developed new models of the atom. These include:

• the  upside-down pineappleplum puddingdough balldoughnut model, where the atom is a ball of positive charge with electrons dotted around
• Rutherford's model - the  directionalnuclearconnectiveelectronic model - based on the observations of  gamma particlealpha particlemetallicbeta particle scattering
•  Marie CurieIsaac NewtonNiels BohrNeil Armstrong's model, where electrons orbit the nucleus
•  Charles DarwinDmitri MendeleevJames ChadwickJames Dalton's model, where neutrons are also in the nucleus

Different  subatomicmagneticalphainfrared particles have different masses and charges. Protons (positive particles) and neutrons (neutral particles) have a mass of  11210-1, and electrons (negative particles) have a very small mass. The relative atomic mass of an atom is the weighted average mass of all of the element's  bondsprotonsisotopessalts.