C4

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  • C4
    • Atoms
      • Atoms make up everything
      • Nucleus made up of protons and neutrons- positive charge
      • Electrons move around the nucleus
      • Protons are heavy and positively charged
      • Neutrons are heavy and neutral
      • Electrons are tiny and negatively charged
      • Number of protons= number of electrons
      • Neutral atoms have no charge overall
      • Each element has a different number of protons
    • Chemical equations
      • Atoms aren't lost or made in chemical reactions
      • Still have the same atoms just rearranged
      • There must be the same number of atoms on both sides
      • Method: just balance one type of atom at a time
    • Line spectrums
      • Some elements emit distinctive colors when heated
      • Each element gives a characteristic line spectrum
      • When electrons become excited release energy as light
      • Different elements emit different wavelengths of light, due to different electron arrangements
      • Line spectrums have identified new elements
    • History of the periodic table
      • Dobereiner tried to organize elements into triads
        • The middle element had a relative atomic mass that was the average of the other two
      • Newland's law of Octaves
        • They didn't have similar products
        • He mixed up metals and non-metals
        • He didn't leave any gaps
        • Every 8th element had similar properties
      • Mendeleev left gaps and predicted new elements
        • With 50 known elements
        • Similar properties in vertical groups
        • Left gaps for new elements
    • Modern periodic table
      • Elements laid out in order of increasing proton number
      • There are repeating patterns in properties
      • Non metals on the right
      • Similar properties are in collumns
      • Vertical collumns are called groups
    • Electron shells
      • Electrons always occupy shells (sometimes called energy levels)
      • Lowest energy levels are always filled first
      • Atoms like having fill outer shells, not full makes them want to react
      • 1st shell only holds 2, the rest hold 8
    • Ionic bonding
      • Ions are made when atoms gain or lose electrons
      • A shell with one electron wants to get rid of it
        • All group 1 elements have one electron in outer shell- when lostthey become positive
      • transferring electrons forms ionic bond
      • oppositely charged ions are strongly attracted to each other
      • Regular lattice , can conduct if molten or dissolved in water
    • Ions and formulas
      • The charges in an ionic compound add up to zero
      • If ions have different size charges, you need to put in some numbers to balance things up
      • If you know the formula of a salt and the charge on one of the ions, you can work out the charge on the other Ion
    • Group 1- Alkali metals
      • Lithium, sodium and potassium
      • All have one outer shell electron
      • Become more reactive as you go down because the outer electron  is easier lost- further from nucleus
      • Have higher density lower down because atoms have more mass
      • Reaction with cold water produces hydrogen gas
      • Reaction with chlorine produce salts
    • Group 7 halogens
      • Chlorine, bromine and iodine
      • 7 outer electrons
      • Diatomic molecules- pairs of atoms
      • become less reactive as you move down
        • Outer electrons are further from the nucleus and so additional electrons are attracted less strongly
      • Non metals with coloured vapours
      • React with alkali metals to make salts
      • React with iron to make coloured solids ( iron halides)
      • Displacementreactions mean the less reactive elements in a compound are pused out by more reactive ones

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