Unit 1

1. factors influencing it:
   1. nuclear charge

      Nota:

      • : a large nuclear charge means the outer electron is difficult to remove, so the inisation energy is large
   2. atomic radii

      Nota:

      • in larger atoms the outer most electron is father away from the nucleus and so is less attracted, so therefore easier to remove
   3. Electron shielding

      Nota:

      • if more inner electron shells shield the nuclear charge from the outer electron, it will be easier to remove and therefore a low ionisation enery
2. first ionisation energy defintion

   Nota:

   • the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1+ ions
3. across a period

   Nota:

   • a general increase: increasing nuclear charge smaller atomic radii similar shielding
4. down a group

   Nota:

   • general decrease: larger atomic radii more shielding larger nuclear charge is outweighed by the previous two factors

Nota:

• bonding between non metals and metals electrostatic attraction between two oppositely charged ions arises when an electron is transferred from one atom to another.

Nota:

• bonding between non-metals sharing of a pair of electrons between two atoms, with one electron being donated from each atom

Nota:

• same as a covalent bond, however the shared electrons are both donated from one of the atoms in the bond.

Nota:

• linear: 180 non linear: 104.5 Pyramidal: 107 tetrahedral: 109.5 octahedral: 90 trigonal bipyramidal: 90 and 120 trigonal planar: 120 Lone pair of electrons>bonded pair

Nota:

• covalently bonded. bond polarisation is when the bond had become slightly ionic in character because it has a dipole moment. between a slightly negative and slightly positive atom bonding.

1. van der waals forces

   Nota:

   • instantaneous dipole between polar bond induces an instantaneous dipole in neighbouring molecule
2. permanent dipole-dipole forces

   Nota:

   • occurs between molecules with permanent dipoles, a slightly negative atom on one molecule attracts the slightly positive atom on another molecule causing electrostatic forces to occur
3. hydrogen bonding

   Nota:

   • relatively strong type of permanent dipoleoccuring between a molecule with H and O, N or F

Nota:

• has a high surface tension and forms a meniscus because the hydrogen bonds pull the water surface downwards

1. ice lower density than water

   Nota:

   • a whole network of hydrogen bonds, and are kept apart to form a littice by this arrangement, giving a lot of space in the structure making ice lower density than water