chemistry paper 1

• alkalis

  elements in group 1

  have a pH range of 8 to 14
• atom

  smallest part of an element that can exist

  all substances are made of atoms
• atomic nucleus

  positively charges object made of protons and neutrons

  at the centre of every atom

  has 1 or more electrons orbiting
• atomic number

  number of protons in the nucleus

  number on the bottom
• chromatography

  separation technique used to separate mixtures
• compound

  substance made of 2 or more types of atoms chemically combined
• crystallisation

  separation technique used to produce solid crystals from a solution by evaporating the solvent
• displacement

  chemical reaction where a more reactive element displaces a less reactive element from its compound
• electron

  negatively charged subatomic particle that orbits the nucleus at different distances

  very small relative mass
• electron shell

  different energy levels in atoms occupied by electrons
• element

  substance made of 1 type of atom
• filtration

  separation technique that separates solids from liquids
• fractional distillation

  method of separating substances according to their boiling points
• groups

  columns on the periodic table
• halogens

  elements in group 7
• ion

  atom with an electric charge due to the loss or gain of electrons
• isotope

  atom with the same number of protons but different number of neutrons
• mass number

  number of protons and neutrons

  number at the top
• metals

  elements that react to form positive ions

  found on the left of the periodic table
• mixture

  consists of 2 or more elements not chemically combined
• neutron

  relative mass of 1

  neutral particle in the nucleus
• noble gases

  elements in group 0
• non metals

  elements that react to form negative ions

  found on the right of the periodic table
• nuclear model

  mass was concentrated at the centre of the atom

  nucleus is charged

  third model

  ernest rutherford
• pre 1900 model

  tiny solid sphere that could not be divided

  john dalton

  first model
• plum pudding model

  a ball of positive charge with negative electrons scattered through it

  JJ Thompson

  shows that an atom must contain small negative charges

  second model
• bohr model

  electrons orbit the nucleus at specific distances

  niels bohr

  shows that electrons orbited in fixed shells

  fourth model
• proton

  relative mass of 1

  positively charged particle in the nucleus
• relative atomic mass

  average value that takes account of the abundance of isotopes
• simple distillation

  procedure where 2 liquids with different boiling points can be separated
• transition metals

  collection of metallic elements in the middle of the periodic table
• coarse particles

  also known as dust

  diameter of 1 x 10-5m and 2.5 x 10-6
• conductor

  material that contains charged particles that are free to move to carry electrical or thermal energy
• covalent bond

  shared pair of electrons between 2 non metals
• diamond

  giant covalent structure

  made of carbon atoms that form 4 covalent bonds with 4 other carbon atoms
• electrostatic forces

  smallest whole number ratio of atoms
• fine particles 


  1 x 10-7m and 2.5 x 10-6m
• fullerenes

  molecules of carbon atoms with hollow shapes

  structures are based on hexagonal rings of carbon
• gas

  state of matter where particles have the most energy

  particles are spread out and move randomly in all directions
• graphene

  single layer of graphite