Atomic structure and periodic table

• Atom

  The smallest part of an element that cannot be chemically broken down
• Element

  Made of only one type of atom, each with its own symbol
• Compound

  A pure substance made from more than one type of element chemically bonded together.
• Naming a compound with two elements (usually a metal and a non-metal)

  1. Metal name does not change

  2. Non-metal name ends in 'ide'
• Naming a compound with a metal that reacts with ions that consist of two or more non-metal atoms covalently bonded together

  1. Metal name does not change

  2. Non-metal name ends in 'ate'
• Compounds cannot be separated by physical means, only by chemical means
• The components of a compound are chemically combined in fixed proportions
• Compounds can be represented by formulae using the symbols of the atoms they are formed from
• Types of elements

  • Metals
  • Non-metals
• Compound

  Two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of atoms from which they formed
• Naming a compound with two elements (usually a metal and a non metal)

  • The metal name does not change
  • The non-metal's name ends in ide
• Naming a compound with two elements

  • Na2S = sodium sulfide
  • K2O = potassium oxide
• Naming a compound with a metal that reacts with ions that consist of two or more non-metal atoms covalently bonded together

  • The metal name does not change
  • The non-metal's name ends in ate if oxygen is present
• Naming a compound with a metal that reacts with ions that consist of two or more non-metal atoms covalently bonded together

  • Na2CO3 = sodium carbonate
  • KNO3 = potassium nitrate
• Word equation

  • methane + oxygen → carbon dioxide + water
• Symbol equation

  • CH4 + 2O2 → CO2 + 2H2O
• Balancing chemical equations

  • We can ONLY add BIG numbers to the front of a substance
  • We can tell elements within a compound by BIG letters
  • We can check an equation is balanced by counting the number of each type of atom on either side
• Balanced chemical equation

  • 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
• Reaction between copper sulfate and sodium hydroxide

  1. copper sulfate + sodium hydroxide → sodium sulfate + copper hydroxide

  2. CuSO4(aq) + 2NaOH(aq) → Na2SO4(aq) + Cu(OH)2(s)
• Precipitate

  Solid formed in a chemical reaction, indicated by (s) state symbol
• Ionic equation for the reaction between copper sulfate and sodium hydroxide

  Cu2+(aq) + 2OH–(aq) → Cu(OH)2(s)
• Reaction between sodium and water

  1. sodium + water → sodium hydroxide + hydrogen

  2. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
• Mixture

  Two or more elements or compounds not chemically combined together, where the chemical properties of each substance are unchanged
• Separating mixtures

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Chromatography
• Filtration

  • Separates insoluble substances from soluble substances
• Crystallisation

  • Separates a soluble substance from a solvent by evaporation
• Simple distillation


  • Separates a liquid from a mixture by evaporation and condensation
• Fractional distillation

  • Separates a mixture into different fractions based on different boiling points
• Chromatography

  • Separates small amounts of dissolved substances by running a solvent along absorbent paper
• Chadwick interpreted an unknown radiation produced from beryllium atoms with alpha particles as being composed of particles with a neutral electrical charge and the approximate mass of a proton. This particle became known as the neutron.
• Atomic model

  Development of the atomic model
• Early atomic models

  • John Dalton - tiny spheres that could not be divided
  • JJ Thomson - electron discovered, plum pudding model
  • Rutherford, Geiger and Marsden - nuclear model
  • Niels Bohr - electrons orbit nucleus at specific distances in fixed energy levels
• Positive charge of nucleus could be subdivided into particles of positive charge - protons.
• James Chadwick provided evidence for the existence of neutrons within the nucleus.
• An atom contains equal numbers of protons and electrons.
• Atoms have no overall electrical charge because the number of positive protons equals the number of negative electrons.
• Atomic number

  Number of protons
• Mass number

  Number of protons and neutrons
• Isotope

  Atoms of the same element with different numbers of neutrons
• Relative atomic mass

  Average mass of the isotopes of an element, taking into account their abundance