Chemistry: Atomic Structure and the Periodic Table: Key terms

• Atom


  the smallest part of an element that can exist
• Element

  a substance made of only one type of atom
• Compound


  a substance containing atoms of two or more elements, which are chemically combined in fixed proportions
• Equation


  a scientific statement that uses chemical names or symbols to sum up what happens in a chemical reaction
• Reactants


  the substances that react together in a chemical reaction
• Products


  the substances produced in a chemical reaction
• Mixture


  a combination of two or more elements or compounds, which are not chemically combined together
• Filtration


  separation techniques used to separate insoluble solids from soluble solids
• Crystallisation


  technique used to obtain a soluble solid from a solution
• Simple distillation


  technique used to separate a substance from a mixture due to a difference in the boiling points of the components in the mixture
• Fractional distillation


  a separation technique used to separate mixtures which contain components with similar boiling points
• Chromatography


  a separation technique used to separate the coloured components of mixtures
• Electron


  a subatomic particle with a relative mass that is very small and relative charge of -1
• Neutron


  a subatomic particle with a relative mass of 1 and no charge
• Proton


  a subatomic particle with a relative mass of 1 and relative charge of +1
• Atomic number


  the number of protons in the nucleus of an atom
• Mass number


  the total number of protons and neutrons in the nucleus of an atom
• Isotope


  atoms of the same element that have the same atomic number but a different mass number
• Ion

  atoms that have gained or lost electrons and now have an overall charge
• Electron configuration


  represents how the electrons are arranged in shells around the nucleus of an atom
• Mendeleev


  the Russian chemist who devised the periodic table
• Noble gases


  unreactive non-metal elements that have a full outer shell of electrons and are found in Group 0 of the periodic tab
• Alkali metals


  elements in Group 1 of the periodic table
• Halogens


  elements in Group 7 of the periodic table
• Displace


  to take the place of (another element, e.g. in a reaction)
• Tranition metals

  metals that have typical metal properties and are found in the middle of the periodic table
• Catalyst


  a substance that speeds up the rate of a chemical reaction, but is not used up in the reaction itself