Soft: weak VDW's forces between the layers allowing them to slide. Polar bonds in a non polar molecule A molecule may have polar covalent bonds because the molecules are symmetrical. Linear shaped molecules E. This causes an instantaneous dipole temporarily. Graphite Giant covalent lattice with layers of carbon atoms.
Conducts electricity: delocalised electrons between carbon layers. The dipoles act in opposite directions and cancel each other out. This temporary dipole induces a dipole in neighbouring molecule.
They have the same number of electrons in their outer shell. Don't conduct in solid state: fixed position. Simple molecular lattice E. Soluble in polar solvents, surround and break down lattice. Chemists use amount of substance as a means of counting atoms Mole The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon — 12 isotope The Avogadro Constant The number of atoms per mole of the carbon- 12 isotope 6.
Hard: strong covalent bonds throughout tetrahedral structure.
Therefore attraction increases between delocalised electrons and metal ions stronger metallic bonding. Exceptions of the octet rule When there are not enough electrons to complete the octet.
Mass number The number of protons and neutrons in the nucleus of an atom. Covalent bond A shared pair of electrons occurs between two non metals. H2O H2S 2 bonded pairs 2 lone pairs Giant covalent lattice E. Pauling scale Electronegativity increases to the top right of the periodic table, with F being the most electronegative.
Special properties of water Ice is less dense than water: the hydrogen bonds hold H2O molecules further apart in an open lattice. H2O has a higher than expected boiling point: hydrogen bonds are the strongest intermolecular force therefore require more energy to break. Order of the orbitals 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 max 36 electrons First ionisation energy The amount of energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of positive gaseous ions.
Permanent dipole A difference in electronegativity between 2 atoms results in a small charge difference. Why do isotopes have similar chemical properties. Expansion of the octet rule When each atom has more than 8 electrons.
Ductile: drawn out wires. More electrons result in larger temporary and induced diploles, which results in a greater force of attraction between molecules.
Van der waals' forces Forces arise due to movement of electrons uneven distribution. Orbital A volume of space that can hold up to two electrons with opposite spins.
Don't conduct electricity: no free moving charged particles Diamond Giant covalent lattice. Malleable: hammered into shape.
Permanent dipole-dipole forces One molecule can attract the opposite permanent dipole in a neighbouring molecule.
Don't conduct electricity: no free charged particles. Conduct electricity: delocalised electrons are free to move. Atoms of the same element with different numbers of neutrons Atomic Proton Number The number of protons in the nucleus of an atom Mass Nucleon Number The number of particles protons and neutrons in the nucleus Ion A positively or negatively charged atom or covalently bonded group of atoms a molecular ion Relative Isotopic Mass The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon - 12 Relative Atomic Mass The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon- 12 Relative Molecular Mass The weighted mean mass of a molecule compared with one twelfth of the mass of an atom of carbon- 12 Relative Formula Mass The weighted mean mass of a formula unit compared with one twelfth of the mass of an atom of carbon- 12 Amount of substance The quantity whose unit is the mole.
Metal bonding The strong electrostatic force of attraction between positive metal ions and delocalised electrons.
Dative covalent bond A shared pair of electrons, both of which come from the same atom. Isotopes Atoms of the same element with different numbers of neutrons. OCR A-Level Chemistry A (H & H) and Chemistry B (Salters) (H & H) past exam papers and marking schemes, the past papers are free to download for you to use as practice for your exams.
Chemistry revision F View full resource. Flashcards by James Farley, created about 4 years ago. OCR AS level Chemistry F 89 9 0 No tags. David Kemp OCR Chemistry A Unit 1: F 5 | P a g e (d) state that an alkali is a soluble base that releases OH– ions in aqueous solution; OH-ions are added to neutralise H+ ions, hence why bases neutralise acids.
(e) state the formulae of the common alkalis. Study CHEMISTRY F Revision Cards (Mrs. Foulston) Flashcards at ProProfs /5.
Aug 02, · The final assessment opportunity (first time entries) for these qualifications (H, H) was in summer A resit opportunity will be available in summer Learn about resit arrangements for ‘legacy’ GCSEs, AS and A Levels.
For centres in Northern Ireland, please refer to the notice to centres for the final assessment opportunities. Covers the limited amount of Group 4 chemistry (carbon, silicon, germanium, tin and lead) required by UK A level syllabuses.
In particular, it covers the trend from non-metal to metal as you go down the group, and the increasing tendency towards an oxidation state of +2. Also a certain amount of chemistry of the chlorides and oxides.Revision of chemistry f321