MASS & CHARGE
- Proton- positive, mass 1
- electron- negative, mass 0
- neutron- neutral, mass 1
- 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.
How atoms combine
- 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.
- 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.
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.
- 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)
- 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.