Chemical Science Pre-Test Notes

Part A: Multiple Choice Questions

  • Question 1: Acids have a pH below 7, and bases have a pH above 7.
  • Question 2: The atomic number refers to the number of protons in an atom.
  • Question 3: The nucleus of the atom contains neutrons and protons.
  • Question 4: The atomic mass refers to the number of protons + neutrons.
  • Question 5: In the Periodic Table, unreactive elements belong to Noble Gases.
  • Question 6: Elements in Group 2 of the Periodic Table have 2 outer shell electrons.
  • Question 7: Different isotopes of the same element contain a different number of neutrons.
  • Question 8: Properties of a metal include being shiny and conducting electricity.
  • Question 9: In the chemical reaction iron chloride + sodium sulphate -> iron sulphate + sodium chloride, the reactants are iron chloride and sodium sulphate.
  • Question 10: The chemical reaction iron chloride + sodium sulphate -> iron sulphate + sodium chloride is an example of a double replacement reaction.

Part B: Short Answer

  • Question 1:
    • The columns on the periodic table are known as groups.
    • The horizontal rows on the periodic table are known as periods.
  • Question 2: Fluorine has:
    • 9 protons
    • 9 electrons
    • 19−9=1019 - 9 = 10 neutrons
  • Question 3:
    • Carbon:
      • Atomic number: 6
      • Bohr's electron configuration: (2, 4)
    • Sodium:
      • Atomic number: 11
      • Bohr's electron configuration: (2, 8, 1)
  • Question 4:
    • Element with electron configuration 2.8.5: Group 15 (or 5A), Period 3
    • Calcium (atomic number 20): Group 2, Period 4, electron configuration 2.8.8.2
  • Question 5: Magnesium metal and hydrochloric acid
    • This is a chemical change because new substances are produced.
    • Reactants: magnesium and hydrochloric acid.
    • Products: magnesium chloride & hydrogen gas.
    • Word equation: magnesium + hydrochloric acid → magnesium chloride + hydrogen gas
    • Type of reaction: Single replacement
  • Question 6:
    • Factors that make sugar dissolve more quickly:
      • Crushing the sugar cube
      • Heating up the coffee in the microwave
      • Stirring the coffee
    • A catalyst speeds up a chemical reaction.