Topic 1

• The number of protons in a nucleus.

  Atomic number
• The number of atoms, molecules or ions in a mole of a given substance, equal to moles multiplied by 6.02 x 10^23.

  Avagadro’s constant
• A substance made up of two or more types of atoms chemically combined together.

  Compound
• A material that contains charge particles which are free to move to carry electrical or thermal energy.

  Conductor
• A law which states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

  Conservation of mass
• A shared pair of electrons between two non-metals.

  Covalent bond
• Dalton described atoms as solid spheres, stating that different spheres made up the different elements.

  Dalton model
• A giant covalent structure which is made up of carbon atoms each of which form four covalent bonds with four other carbon atoms.

  Diamond
• Different energy levels in atoms occupied by electrons.

  Electron shell
• The strong forces of attraction between oppositely charged ions.

  Electrostatic forces
• The simplest whole number ratio of atoms of each element in a compound.

  Empirical formula
• Molecules of carbon atoms with hollow shapes. The structures are based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms. Examples include graphene and C60.

  Fullerenes
• Molecules containing many atoms covalently bonded together, such as silicon dioxide, graphene and diamond.

  Giant covalent molecule
• A single layer of graphite with properties that make it useful in electronics and composites.

  Graphene
• A giant covalent structure which is made up of carbon atoms each of which form three covalent bonds with three over carbon atoms. The atoms form layers of hexagonal rings which have no covalent bonds between them. There is one delocalised electrons per carbon atom which is free to move to carry charge.


  Graphite
• The forces which exist between molecules that impact physical properties such as melting/boiling point.

  Intermolecular forces
• The bond formed between the oppositely charge ions when a metal atom loses electrons(s) and a non-metal gains electron(s).

  Ionic bond
• Chemical compound formed of oppositely charge ions, held together by strong electrostatic forces.

  Ionic compound
• A repeating regular arrangement of atoms/ions/molecules. This arrangement occurs in crystal structures.

  Lattice
• The reactant that is completely used up since it limits the amount of products formed.

  Limiting reactant
• The total number of protons and neutrons in the nucleus

  Mass number
• The bond present in metals between the positive metal ions and negatively charged delocalised electrons.

  Metallic bond
• Elements that react to form positive ions. Found to the left and towards the bottom of the periodic table.

  Metals
• The actual ratio of atoms of each element present in a compound.

  Molecular formula
• A group of at least two atoms held together by covalent bonds.

  Molecule
• Large long-chain molecules made up of lots of small monomers joined together by covalent bonds.

  Polymers
• An average value that takes into account the abundances of the isotopes of the element.

  Relative atomic mass
• The sum of the relative atomic masses of the atoms in the numbers shown in the formula. It is numerically equation to the mass of one mole of a substance in grams.

  Relative formula mass
• Molecules containing a fixed number of atoms covalently bonded together.

  Simple molecules