Key Terms

• Alkali Metals

  The elements in group 1 of the Periodic Table.
• Atoms

  The smallest part of an element that can exist. Everything is made up of Atoms.
• Atomic Nucleus

  Positively charged object composed of protons and neutrons at the centre of every atom with one or more electrons orbiting it on shells (energy levels).
• Atomic Number

  The amount of protons in the atom.
• Chromatography

  A separation technique used to separate a mixture of chemicals by distributing the components between two phases.
• Compound

  A substance made up of two or more types of Atoms chemically bonded together.
• Crystallisation

  A separation technique used to produce solid crystals from a solution by evaporating the solvent.
• Displacement

  A reaction in which a more reactive element displaces a less reactive element from its compound.
• Electron

  Negatively charged subatomic particle which orbits the nucleus at different energy levels (Shells). Very small mass (negligible).
• Electron Shell

  Different energy levels in Atoms occupied by electrons.
• Element

  A substance made up of one type of atom only.
• Filtration

  A separation method to separate insoluble solids from liquids.
• Fractional Distillation

  A method of separation to separate objects based on their differing boiling points.
• Group (Periodic Table)

  The columns of the periodic Table represent different groups of elements. All elements within the group have similar properties. Group number represents amount of electrons in the outer energy level (shell).
• Halogens

  The elements in group 7 of the periodic Table.
• Ion

  A charged atom due to the gain/loss of electrons.
• Isotope

  Atoms of the same element with the same number of protons but a different number of neutrons.
• Mass Number

  The amount of protons + neutrons in an atom.
• Metals

  Elements that react to form positive ions. They are found to the left and the bottom of the periodic Table.
• Mixture

  A substance containing two or more elements not chemically bonded together.
• Neutron

  A neutrally charged subatomic particle present in the nucleus of the atom. Relative mass of 1.
• Noble Gasses

  The elements in group 0 of the periodic Table.
• Non-metals

  Elements that react to form negative ions. They are found towards the right and top of the periodic Table.
• Nuclear Model

  The nuclear Model stated that the mass was concentrated in the centre of the atom and that the nucleus was charged.
• Periodic Table

  The Table of elements arranged in order of atomic number in such a way that elements with similar properties can be found in the same column (Group).
• Plum Pudding Model

  Atomic model made after the discovery of the electron. The model suggests that the atom is a ball of proton (positive charge) with electrons randomly dotted throughout.
• Proton

  Positively charged subatomic particle found in the centre of the atom (Nucleus). Relative mass of 1.
• Relative Mass

  An average value that takes account of the abundance of isotopes of the element.
• Simple distillation

  A method by which elements with different boiling points can be separated.
• Transition Metals

  The collection of elements in the middle of the periodic Table.