chemistry aqa additional - key terms

these cards are definitions of key words from additional chemistry

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  • Created by: zofia
  • Created on: 12-04-11 13:22


  • very tiny
  • made of protons, neutrons and electrons
  • makes up everything in the universe
  • not charged (if it is its called an ion)
  • number of protons = number of electrons
  • number of protons + number of neutrons = mass number
  • most of the atom is empty space
  • protons and neutrons are in the middle of the atom in the nucleus
  • electrons are in shells around the nucleus
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  • just a charged atom
  • this usually happens when the atom is trying to bond to another atom
  • the loss or gain of electrons makes it charged
  • if it looses one electron it is +1 charged
  • if it gains two electrons it is -2 charged
  • because electrons are -1 charged
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  • elements consist of one type of atom only
  • quite a lot of everyday substances are elements:
  • copper
  • aluminium
  • iron
  • oxygen
  • nitrogen 
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  • compounds are chemically bonded
  • compounds are formed when two or more elements chemically react together
  • its difficult to separate the two elements out again
  • the properties of a compound are totally different from the properties of the original elements
  • carbon + oxygen -> carbon dioxide
  • hydrogen + oxygen -> hydrogen oxide (water)
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  • isotopes are the same element but with a different number of neutrons, thats it
  • unfortunatly you have to learn the posh way of saying the same thing, which is:
  • isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons
  • if they have a different proton number they're a different element

will this be in your exam - isotope so...

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carbon dating

  • an isoptope of carbon is used for carbon dating
  • carbon 12 has 6 protons, 6 electrons, 6 neutrons
  • carbon 14 has 6 protons, 6 electrons, 8 neutrons
  • when things die, c-14 is trapped inside the daed material, and it gradually decays into nitrogen
  • so by mesuring the proportion of c-14 found in some old axe handle you can calculate how long ago it was living wood
  • so you know how long ago it was cut down and made into the axe
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  • the mole is simply the name given to a certain number
  • just like a million is: 1 000 000
  • a mole is: 602 300 000 000 000 000 000 000
  • when you get precicly that number of atoms of carbon 12 it weighs exactly 12g
  • iron has an Ar (mass number) of 56, so one mole of iron = 56g
  • oxygen has an Ar of 16, so one mole of oxygen = 16g
  • this means that 12g of carbon, or 56g of iron , or 16g of oxygen, all contain the same number of particles, namely one mole or 602 300 000 000 000 000 000 000 atoms
  • number of moles=mass in g/Mr (or Ar)
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