Atomic structure and the periodic table

• What are all substances made of?

  Atoms
• What is an atom?

  The smallest part of an element that can exist
• How are atoms of each element represented?

  By a chemical symbol
• What does the symbol 'O' represent?

  An atom of oxygen
• How many different elements are there approximately?

  About 100
• Where are elements shown?

  In the periodic table
• How are compounds formed?

  By chemical reactions between elements
• What do chemical reactions always involve?

  The formation of one or more new substances
• What do compounds contain?

  Two or more elements chemically combined in fixed proportions
• How can compounds be represented?

  By formulae using the symbols of the atoms
• How can compounds be separated into elements?

  Only by chemical reactions
• How can chemical reactions be represented?

  By word equations or equations using symbols and formulae
• What will students be supplied with for the exam?

  A periodic table
• What should students be able to use from the periodic table?

  The names and symbols of the first 20 elements
• What are the elements in Groups 1 and 7?

  They are specific groups of elements in the periodic table
• What should students be able to name from given formulae or symbol equations?

  Compounds of the first 20 elements
• What should students be able to write for the reactions in this specification?

  Word equations
• What should students be able to write for the reactions in this specification besides word equations?

  Formulae and balanced chemical equations
• What is required for HT students regarding equations?

  To write balanced half equations and ionic equations where appropriate
• What is a mixture?

  A combination of two or more elements or compounds not chemically combined
• What happens to the chemical properties of substances in a mixture?

  They remain unchanged
• How can mixtures be separated?

  By physical processes
• What are some physical processes used to separate mixtures?

  Filtration, crystallisation, simple distillation, fractional distillation, and chromatography
• What do physical processes not involve?

  Chemical reactions
• What is the significance of new experimental evidence in science?

  It may lead to a scientific model being changed or replaced
• What were atoms thought to be before the discovery of the electron?

  Tiny spheres that could not be divided
• What model of the atom was proposed after the discovery of the electron?

  The plum pudding model
• What did the plum pudding model suggest about the atom?

  It is a ball of positive charge with negative electrons embedded in it
• What conclusion was drawn from the alpha particle scattering experiment?

  The mass of an atom is concentrated at the nucleus
• What model replaced the plum pudding model?

  The nuclear model
• What did Niels Bohr suggest about electrons?

  They orbit the nucleus at specific distances
• What did Bohr's theoretical calculations agree with?

  Experimental observations
• What idea emerged about the positive charge of the nucleus?

  It could be subdivided into smaller particles called protons
• Who provided evidence for the existence of neutrons?

  James Chadwick
• When did Chadwick provide evidence for neutrons?

  About 20 years after the nucleus became an accepted idea
• What should students be able to describe regarding the atomic model?

  The historical context and development of scientific methods and theories
• What is the relative electrical charge of protons?

  Positive
• What is the relative electrical charge of electrons?

  Negative
• What is the relative electrical charge of neutrons?

  Neutral
• In an atom, what is equal to the number of protons?

  The number of electrons