Atoms

Atoms

1. Atoms

   • Atoms:Basics
     • No. of protons=no.of electrons
     • small no.=atomic number
     • big no.=relative mass
     • atomic no.=no. of protons/electrons
     • protons+neutrons=relative mass
     • relative mass-atomic no.=no. of neutrons
     • Atom-Smallest indivisible particle of an element that can exist
     • Molecule-When 2 or more atoms of an element chemically combine. Smallest particle of an element or compound which can exist on its own
       • E.g. Oxygen is a molecule (O2) so is hydrogen(H2) and nitrogen(N2) etc.
     • Atomicity-No. of atoms in a molecule
   • Investigating mass of reactants&products
     • 'Total mass of products formed in chemical reaction, equal to total mass of reactants'.
       • - Law of Conservation of Mass
     • s-solid
     • l-liquid
     • g-gas
     • aq-aqueous(mixed with water)
   • Separating mixtures
     • Compound
       • fixed composition:elements present=particular compound
       • chemical reactions must be used to seperate
       • chemically combined
     • Mixture
       • no fixed composition:properties vary depending on amount of each substance mixed with the other
       • seperate easily (filtration,chromotography..)
       • not chemically combined
     • Filtration
       • separates insoluble substances in solvent from soluble
     • Crystallisation
       • separates soluble solid from solvent
     • Distillation
       • collects solvent(s) itself,instead of letting it evaporate
     • Chromotography
       • Separates&identifies substances from mixtures in solution-paper chromotgraphy.Process works as some compounds in mixtures dissolve better than others in solvent
         • Chromotogram-paper record of seperation. More soluble a substance in solvent further up paper it's carried

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