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elements of life (tests for ions (flame tests (1) dip nichrome loop into…

- - - - tiny positively charged nucleus at the centre of atom- where most of mass is concentrated
      - nucleus is surrounded by a cloud of freely orbiting electrons
      - most of atom is empty space
- - - - gives a metal hydroxide + hydrogen
      - e.g. M + 2H20 -----> M(OH)2 + H2
    - - produces white solids
      - e.g. 2M + O2 ----> 2MO
  - - - the oxides of group 2 react with water to form metal hydroxides which dissolve
      - the hydroxide ions (OH-) make the solution strongly alkaline
      - More alkaline down the group
    - - form solutions of corresponding salts
- - - - have a -1 charge
      - they are found in shells
      - shells make up the majority of the atom
      - mass= 1/2000
    - - most of the mass of the atom is concentrated at the nucleus
      - the diameter of the nucleus is very small compared to the rest of the atom
      - the nucleus is where protons and neutrons are found
    - - mass=1
      - has a charge of 0
    - - mass=1
      - has a charge of +1
  - - - negative charge means theres more electrons than protons
      - the number next to the - indicates number of electrons added
    - - positive charge means theres fewer electrons than protons
      - the number next to the + indicates number of electrons lost
- - - - 1 orbital
      - maximum number of electrons= 2
    - - 3 orbitals
      - maximum number of electrons = 6
    - - 5 orbitals
      - maximum number of electrons= 10
    - - 7 orbitals
      - maximum number of electrons = 14
  - - - write electronic structure of atom
      - add or remove electrons from the highest occupied sub shell
- - - - LINEAR
      - treat double bond same as single
      - 180 degrees angle
    - - TRIGONAL PLANAR
        
        no lone pairs
        
        120 degrees
      - BENT/ non linear
        
        one lone pair
        
        117.5 degrees
    - - TETRAHEDRAL
        
        no lone pairs
        
        109.5 degrees
      - TRIGONAL PYRAMIDAL
        
        one lone pair
        
        107 degrees
      - BENT/ non linear
        
        2 lone pairs
        
        104.5 degrees
    - - TRIGONAL BIPYRAMIDAL
      - 90 and 120 degrees
    - - OCTAHEDRAL
      - 90 degrees
- - - - ions arrange themselves in order to maximize attractions and minimise repulsions
  - - - the ions in a liquid/ solution are free to move and carry charge
    - - giant ionic lattices are held together by strong electrostatic forces
      - lots of energy is needed to overcome these forces
    - - water molecules are POLAR
      - water molecules pull ions away from lattice and cause it to dissolve
- - - - intermolecular forces between molecules are weak
    - - the polar water molecules are more attracted to eachother than the molecular substance
- - - - needs a lot of energy to break bonds before substance melts
    - - strong bonds throughout lattice
    - - vibrations travel easily through stiff lattices
    - - don't contain ions
    - - no delocalised electrons to carry charge throughout the structure (all are bonded)
  - - - high melting points
        
        strong metallic bonding (the more electrons there are the stronger the bonding)
        
        the size of the metal ion and the structure of the lattice effect it
      - ductile
        
        no bonds holding specific ions together
        
        the metal ions slide over eachother when the structure is pulled
      - good thermal conductors
        
        delocalised electrons can pass kinetic energy to eachother
      - good electrical conductors
        
        delocalised electrons are free to move and carry charge
        
        impurities can reduce this (electrons transfer to impurities are form anions)
      - insoluble
        
        strength of metallic bonds
- - - - melting points increase across period (metallic bonding gets stronger)
      - bonds get stronger due to increasing number of delocalised electrons and a decreasing ionic radius
      - creates a higher charge density- attracts ions more strongly
    - - a lot of energy is needed to break these strong bonds
      - carbon and silicon have the highest melting points in their periods
    - - their melting points depend on intermolecular forces
      - intermolecular forces are weak and easily broken
      - have low melting points
  - - - atomic radius
        
        the further the outer shell electrons from the positive nucleus the less they will be attracted
        
        it will be lower
      - nuclear charge
        
        this the positive charge on the nucleus caused by protons
        
        the more protons the more they will attract electrons
        
        it will be higher
      - electron shielding
        
        the inner electron shells shield the outer shell electrons from the more attractive force of the nucleus
        
        it will be lower
- - - - energy is related to frequency
      - when em radiation is passed through a gaseous element the electrons only absorb certain frequencies corresponding to different energy levels
      - the missing frequencies show up as dark lines
    - - when electrons drop to lower energy levels they give out certain amounts of energy
      - each element has a different electron arrangement so the frequencies of radiation absorbed and emitted are different
      - has coloured lines
- - - - the y axis= abundance of ions or the relative isotopic abundance for elements
      - the x axis= relative mass