C1a

• What is the smallest part of an element that can exist?

  Atom
• What is the approximate radius of an atom?

  Around 0.1 nanometres
• What does an element contain?

  Only one type of atom
• How many different elements are there approximately?

  Around 100
• What is a compound?

  Two or more elements chemically combined
• How can compounds be separated into elements?

  By chemical reactions
• What are the methods to separate mixtures?

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Chromatography
• What does filtration separate?

  An insoluble solid from a liquid
• What is an example of filtration?

  Getting sand from a mixture
• What is an example of crystallisation?

  Obtaining pure crystals of sodium chloride
• What is the purpose of simple distillation?

  To separate a solvent from a solution
• What is an example of simple distillation?

  Getting pure water from salt water
• What does fractional distillation separate?

  A mixture of liquids with different boiling points
• What is an example of fractional distillation?

  Separating compounds in crude oil
• What does chromatography separate?

  Substances that move at different rates
• What is an example of chromatography?

  Separating dyes in food coloring
• What is a mixture?

  Two or more elements or compounds not chemically combined
• How can mixtures be separated?

  By methods like filtration and distillation
• What were the historical models of the atom?

  1. Tiny solid balls (Dalton)
  2. Plum pudding model (Thompson)
  3. Nuclear model (Rutherford)
  4. Bohr model (Bohr)
• What did John Dalton propose about atoms?

  They are tiny solid balls
• What did JJ Thompson discover about atoms?

  Atoms contain small negative charges
• What did Rutherford's experiment show?

  Most of the mass is at the atom's center
• What did Niels Bohr propose about electrons?

  They orbit the nucleus at specific distances

  
• What did Rutherford's scattering experiment involve?

  A beam of alpha particles directed at gold foil
• What happened to most alpha particles in Rutherford's experiment?

  They passed right through the foil
• What happened to a few alpha particles in Rutherford's experiment?

  They were deflected by the positive nucleus
• Who provided evidence for neutrons?

  James Chadwick
• What do chemical equations show?

  How reactions change reactants into products
• What does the law of conservation of mass state?

  Total mass of products equals reactants
• What do word equations use to show reactions?

  Words to show reactants and products
• What is an example of a word equation?

  Magnesium + oxygen → magnesium oxide
• What do symbol equations show?

  Uses symbols to show reactants and products
• What is an example of a symbol equation?

  2Mg + O2 → 2MgO
• What is the mass number?

  The sum of protons and neutrons
• What is the atomic number?

  The number of protons in the atom
• What does the nucleus contain?

  Protons and neutrons
• What do electron shells contain?

  Electrons
• What are isotopes?

  Atoms with the same protons, different neutrons
• How is relative atomic mass calculated?

  Using the formula with isotopes' percentages
• What is the relative atomic mass of chlorine?

  $35.5$