C1 - Atomic Structure and the Periodic Table

• What is an atom?

  The smallest part of an element
• What is an element?

  Substance of only one type of atom
• How are elements listed and how many are there?

  Periodic table, approximately 100
• How can elements be classified based on their properties?

  Metals and non-metals
• What are the new substances called when elements combine?

  Compounds
• What is a compound?

  Elements chemically combined in fixed proportions
• Do compounds have the same properties as their constituent elements?

  No, they have different properties
• What is a mixture, and does it have the same chemical properties as its constituent materials?

  Not chemically combined, same properties
• What are the five methods through which mixtures can be separated, and do they involve chemical reactions?

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Chromatography
  • They do not involve chemical reactions
• What is the purpose of simple distillation?

  To separate liquid from a solution
• In simple distillation, what does the thermometer read?

  Boiling point of the pure liquid
• What is produced in simple distillation?

  A liquid
• What is the main purpose of evaporation?

  Separate solid dissolved in a solvent
• What happens to the solvent in evaporation?

  The solvent evaporates
• What is the key difference in crystallisation compared to evaporation?

  Only remove some of the solvent
• What is formed when some solvent is removed by evaporation in crystallization?

  A saturated solution
• In crystallization, why do crystals form upon cooling?

  Solid becomes less soluble
• How are crystals collected after crystallization?

  Collected via filtration
• What type of mixture is fractional distillation used to separate?

  Mixture of liquids
• What property differences does fractional distillation rely on?

  Different boiling points
• What is the role of the fractionating column?

  Helps to separate compounds
• How does temperature vary along the fractionating column?

  Hot at bottom, cold at top
• What is the purpose of filtration?

  Separate insoluble solid in liquid
• In filtration, what is the insoluble solid called?

  Residue
• In filtration, what is the substance that passes through the filter paper called?

  Filtrate
• What does chromatography separate?

  Substances dissolved in a solvent
• In paper chromatography, what happens as the solvent rises?

  Mixture separates into components
• What is a separating funnel used for?

  Separating immiscible liquids
• How do immiscible liquids behave in a separating funnel?

  Form distinct layers
• Which layer is run off first from a separating funnel?

  Bottom layer, greater density
• According to the plum-pudding model, what is the structure of the atom?

  Ball of positive charge with negative electrons embedded in it
• What does the nuclear model of the atom suggest?

  Electrons orbit in specific shells
• What experiment led to the nuclear model?

  Alpha scattering experiments
• What particles were discovered in the nucleus later on?

  Protons
• What did James Chadwick's work provide evidence for?

  Existence of neutrons
• Describe the structure of an atom.

  Nucleus with orbiting electrons
• What are the relative masses of a proton, neutron and electron?

  1, 1, very small
• What are the relative charges of a proton, neutron and electron?

  1, 0, -1
• Why are atoms electrically neutral?

  Same number of electrons and protons
• What is the radius of an atom?

  0.1 nm