GCSE C4 - Chemical Patterns

GCSE C4 - Chemical Patterns

1. Atoms

   • Nucleus
     • middle of atom
     • contains protons and neutrons
     • makes up almost all of the mass of the atom
     • positive charge
   • Electrons
     • move around the nucleus
     • negatively charged
     • virtually no mass
     • arranged in shells around the nucleus
   • Particles
     • protons are heavy with a positive charge
     • neutrons are heavy and neutral
     • electrons are tiny and negatively charged
   • number of protons = number of electrons

2. Chemical Equations

   • (s) - solid
   • (l) - liquid
   • (g) - gas
   • (aq) - dissolved in water/aqueous
   • nothing 'disappears' in a reaction - it just rearranges

3. Line Spectrums

   • different substances give out different coloured flames
     • lithium produces a red flame
     • sodium produces a yellow flame
     • potassium produces a lilac flame
   • when heated, electrons give out energy as light
     • this can be recorded as a line spectrum
     • different elements emit different wavelengths
     • each element has a different pattern of wavelengths and a different line spectrum
   • they can be used to identify elements

4. History of the Periodic Table

   • originally ordered by atomic mass
   • Newlands didn't leave any gaps for new elements
   • Mendeleev recreated the table
     • he put similar elements in vertical groups
     • he left large gaps in order for new undiscovered elements to fit in

5. The Modern Periodic Table

   • elements are laid out in order of increasing proton number
   • metals are on the left, non-metals on the right
   • elements with similar properties from columns - groups
     • group number tells you how many electrons are on the outer shell
   • rows are called periods and each new period represents another full shell of electrons

6. Electron Shells

   • 1st shell: 2 electrons
   • 2nd shell and all the shells after: 8 electrons
   • an atom is happy if it has a full outer shell
   • an element's electron arrangement determines its chemical properties
   • if a shell isn't full it makes the element want to react