Definitions

• Anion

  A negatively charged ion formed when an atom gains at least 1 electron
• Atom

  The smallest part of an element that can exist
• Atomic nucleus

  Positively charged object composed of protons and neutrons at the centre of every atom with 1 or more electrons orbiting it
• Atomic number

  The number of protons in the nucleus
• Avogadros Constant

  The number of atoms, molecules or ions in a mole of a given substance
• Cation

  A positively charged ion formed when an atom loses at least 1 electron
• Compound

  A substance made up of 2 or more types of atoms chemically combined together
• Concentration

  The amount of substance in a certain volume of a solution
• Conductor

  A material that contains charged particles which are free to move to carry electrical or thermal energy
• Conservation of mass

  A law which states that no atoms are lost or made during a chemical reaction so the mass of the products = the mass of the reactants
• Covalent bond

  A shared pair of electrons between 2 non-metals
• Dalton model

  Dalton described atoms as solid spheres, stating that different spheres made up the different elements
• Diamond

  A giant covalent structure which is made up of carbon atoms each of which form 4 covalent bonds with 4 other carbon atoms
• Electron

  A negatively charged subatomic particle which orbits the nucleus at various energy levels
• Electron shell

  Different energy levels in atoms occupied by electrons
• Electrostatic forces

  The strong forces of attraction between oppositely charged ions
• Element

  A substance made up of only 1 type of atom
• Empirical formula

  The simplest whole number ratio of atoms of each element in a compound
• Fullerenes

  Molecules of carbon atoms with hollow shapes - structures = based on hexagonal rings of carbon atoms but they may also contain rings with 5 or 7 carbon atoms
• Giant covalent molecule

  Molecules containing many atoms covalently bonded together
• Graphene

  A single layer of graphite with properties that make it useful in electronics and composites
• Graphite

  A giant covalent structure which is made up of carbon atoms each of which form 3 covalent bonds with 3 other carbon atoms - the atoms form layers of hexagonal rings which have no covalent bonds between them. There is 1 delocalised electron per carbon atoms which is free to move to carry a charge
• Group

  A column of the periodic table. Elements in the same group have similar chemical properties
• Intermolecular forces

  The forces which exist between molecules. The strength of the intermolecular forces impact physical properties like boiling/melting point
• Ion

  an atom of molecule with an electric charge due to the loss or gain of electrons
• Ionic bond

  The bond formed between the oppositely charged ions when a metal atom loses electrons to form a positively charged ion and a non-metal gains these electrons to form a negatively charged ion
• Ionic compound

  Chemical compound formed of oppositely charged ions held together by strong electrostatic forces
• Isotope

  Atoms of the same element with the same number of protons but a different number of neutrons
• Lattice

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

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

  The total number of protons and neutrons in the nucleus
• Metallic bond

  The bonds present in metals between the positive metal ions and negatively charged electrons
• Metals

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

  The unit for amount of substance. The symbol = mol
• Molecular formula

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

  A group of at least 2 atoms held together by covalent bonds
• Neutron

  Neutral subatomic particle present in the nucleus of the atom. Relative mass of 1
• Non-metals

  Elements that react to form negative ions. Found towards the right and top of the periodic table
• Period

  A row of the periodic table. Elements in the same period have the same number of electron shells
• Periodic table

  Table of elements arranged in order of increasing atomic number and such that elements with similar properties are in the same column