Model of the atom GapFill

All matter is made up of  energycellsionsatoms, which come in different types, called  reactantsatomsparticleselements, represented using symbols which can be found on the  reactivity listperiodic tableInternetcompound sequence. When these react together,  compoundsbeta particlesmixturesatoms are formed, which have formulae to show the  percentageratiopositionimportance of each element.  Pure substancesNeutronsMixturesElectrons contain multiple elements or compounds, and can be  separatedshapedmeltedreacted using filtration, distillation, crystallisation and chromatography.

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

• the  plum puddingupside-down pineappledough balldoughnut model, where the atom is a ball of positive charge with electrons dotted around
• Rutherford's model - the  nuclearconnectiveelectronicdirectional model - based on the observations of  alpha particlebeta particlemetallicgamma particle scattering
•  Niels BohrMarie CurieIsaac NewtonNeil Armstrong's model, where electrons orbit the nucleus
•  James DaltonCharles DarwinJames ChadwickDmitri Mendeleev's model, where neutrons are also in the nucleus

Different  alphamagneticinfraredsubatomic particles have different masses and charges. Protons (positive particles) and neutrons (neutral particles) have a mass of  1-11210, 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.