Zusammenfassung der Ressource
Unit 1
- Electrons, bonding and structure
- ionisation energy
- factors influencing it:
- nuclear charge
Anmerkungen:
- : a large nuclear charge means the outer electron is difficult to remove, so the inisation energy is large
- atomic radii
Anmerkungen:
- in larger atoms the outer most electron is father away from the nucleus and so is less attracted, so therefore easier to remove
- Electron shielding
Anmerkungen:
- 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
- first ionisation energy defintion
Anmerkungen:
- the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1+ ions
- across a period
Anmerkungen:
- a general increase:
increasing nuclear charge
smaller atomic radii
similar shielding
- down a group
Anmerkungen:
- general decrease:
larger atomic radii
more shielding
larger nuclear charge is outweighed by the previous two factors
- ionic bonding
Anmerkungen:
- bonding between non metals and metals
electrostatic attraction between two oppositely charged ions
arises when an electron is transferred from one atom to another.
- covalent bonding
Anmerkungen:
- bonding between non-metals
sharing of a pair of electrons between two atoms, with one electron being donated from each atom
- dative covalent bond
Anmerkungen:
- same as a covalent bond, however the shared electrons are both donated from one of the atoms in the bond.
- bonding angles
Anmerkungen:
- 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
- polarisation
Anmerkungen:
- 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.
- intermolecular forces
- van der waals forces
Anmerkungen:
- instantaneous dipole between polar bond
induces an instantaneous dipole in neighbouring molecule
- permanent dipole-dipole forces
Anmerkungen:
- 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
- hydrogen bonding
Anmerkungen:
- relatively strong type of permanent dipoleoccuring between a molecule with H and O, N or F
- water
Anmerkungen:
- has a high surface tension and forms a meniscus because the hydrogen bonds pull the water surface downwards
- ice lower density than water
Anmerkungen:
- 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