Chemistry Notes. Standard Grade.

Standard grade revision cards!

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  • Created by: Colette
  • Created on: 25-03-10 10:48

ATOM

MASS & CHARGE

  • Proton- positive, mass 1
  • electron- negative, mass 0
  • neutron- neutral, mass 1

working out..

  • protons - equal ro atomic number
  • neutrons - mass number minus atomic number (protons)
  • electrons - equal to the mber of protons

Isotopes are atoms of the one element with different mass numbers with same atmoic number

-ide compounds contain two named elements, -ite + -ate compounds contain oxyen as well as the two na,ed elements.

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How atoms combine

Covalent Bonding

  • in forming a covalent bond atoms achieve the same electron arragement as an atom of a noble gas, stable.
  • Usually only atoms of non-metal elements form covalent bonds.
  • a molecule is a group of atoms held together by covalent bonds.
  • a diatomic molecule contains two atoms joined together
  • EG. hydrogen- H (2), Oxygen- O (2), Nitrogen- N (2), Chlorine- Cl (2)
  • An Oxygen molecule has a double covalent bond;
  • A nitrogen molecule has a triple covalent bond;
  • the diatomic molecules of other elements consist of single covalent bonds.
  • The Protons give a positive charge to the nucleus of the atom.
  • The positive nuclei of both atoms attract the negative shared electrons and this holds the atoms together, Alot of energy is needed to break covalent bonds.
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Fuels

Fuels

  • Are chemicals that burn (react with oxygen) releasing energy.
  • An Exothermic reaction is o in which energy is released
  • Fossil fuels are finite resources; cannot be replaced.

Fractional Distllation

is the process used to separate the different hydrocarbons in crude oil according to their boling points.

Nitrogen makes up approx 80% of air, oxygen makes up 20%.

Carbon Dioxide is formed in the complete combustion of fossil fuels. Carbon monoxide is a poisonous gas.

Catalyic converters in car exhausts convert harmful gases into harmless ones.

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topic 6

Alkanes

  • CnH2n+2
  • cardon to cardbon bonds - single covalent
  • burned in a llimited supply of air carbon monoxide may be produced
  • Cycloalkanes general formula is CnH2n (ring of carbon atoms)

Alkenes

  • CnH2n
  • carbon to carbon double covalent bond
  • undergo addition reactions with hydrogen & bromine (decolourises bromine)

Homologous series - set of compounds with the same general formula and similar chemical properties. Catalytic cracking is a process which breaks unwanted large molecules into smaller more useful molecules, alkenes are also produced.Catalyst speeds up reaction allowing it to take place at a lower temperature.

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Comments

Becky

Brilliant - helps alot :)

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