Paper 1

• What is a mixture made of?

  Two or more substances not chemically joined
• How does filtration work?

  It removes insoluble solids from liquids
• What method would you use to separate salt from seawater?

  Evaporation and crystallization
• What does distillation separate?

  Liquids with different boiling points
• What does chromatography help identify?

  Different substances in ink
• What forms ionic compounds?

  A metal bonding with a non-metal
• What are the properties of ionic compounds?

  High melting points, conduct electricity when dissolved
• What forms covalent compounds?

  Non-metals bonding with each other
• What are the properties of covalent compounds?

  Low melting points, do not conduct electricity
• What do dot and cross diagrams show?

  How electrons are shared or transferred
• What do exothermic reactions do?

  Release energy, increasing temperature
• What do endothermic reactions do?

  Absorb energy, decreasing temperature
• How do energy reaction profiles differ for exothermic and endothermic reactions?

  Exothermic starts high, ends low; endothermic starts low, ends high
• Who arranged elements by atomic mass?

  Dmitri Mendeleev
• What did Mendeleev's periodic table include?

  Gaps for missing elements
• What is electrolysis used for?

  To split compounds using electricity
• What forms at the anode during electrolysis?

  Non-metal ions like oxygen
• What forms at the cathode during electrolysis?

  Metals or hydrogen
• What is the independent variable in an experiment?

  What you change
• What is the dependent variable in an experiment?

  What you measure
• What are control variables?

  Things kept the same for fairness
• What is a key difference between diamond and graphite?

  Diamond is hard; graphite conducts electricity
• How is a soluble salt made?

  When an acid reacts with a base