Science 9 · Unit 2: Properties of materials · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. What does the atomic number of an element tell you?

   • the number of protons and neutrons in each atom
   • the number of neutrons in each atom
   • the number of electron shells
   • the number of protons in each atom
   Check

2. 2. What does the mass number of an element tell you?

   • the number of protons plus neutrons in each atom
   • the number of protons plus electrons in each atom
   • the number of electrons in each atom
   • the number of protons in each atom
   Check

3. 3. Why does an atom have no overall charge?

   • Its neutrons cancel out the charge of the protons.
   • Protons and electrons have no charge.
   • It has the same number of protons (positive) as electrons (negative).
   • It has more neutrons than protons.
   Check

4. 4. Match each particle with where it is and its charge.

   • proton
   • neutron
   • electron

   • in shells around the nucleus; negative
   • in the nucleus; positive
   • in the nucleus; no charge
   Check

5. 5. Carbon has mass number 12 and hydrogen has mass number 1. What does this tell you?

   • A carbon atom has 12 electrons.
   • A carbon atom has about 12 times the mass of a hydrogen atom.
   • A carbon atom is 12 times bigger in size than a hydrogen atom.
   • A carbon atom has 12 protons.
   Check

6. 6. A piece of sodium measuring 1 cm³ has a mass of 0.97 g. A piece of iron measuring 1 cm³ has a mass of 7.87 g. Which is more dense?

   • You can't tell without knowing their atomic numbers.
   • They have the same density.
   • iron
   • sodium
   Check

7. 7. Niels Bohr changed the model of the atom. What was his new idea?

   • Protons move in shells around the electrons.
   • Atoms are solid balls that can't be divided.
   • The nucleus is made of electrons.
   • Electrons move in shells (energy levels) at set distances around the nucleus.
   Check

8. 8. How many electrons can the first electron shell hold?

   • 8
   • 1
   • 2
   • 18
   Check

9. 9. The electronic structure of boron is written 2,3. What does this mean?

   • There are two electrons in the first shell and three in the second shell.
   • There are three electrons in the first shell and two in the second shell.
   • There are two shells with three electrons in each.
   • There are two protons and three electrons.
   Check

10. 10. How many protons are there in an atom of beryllium (atomic number 4)?

    • 2
    • 5
    • 4
    • 9
    Check

11. 11. Magnesium has atomic number 12. What is its electronic structure?

    • 2,10
    • 2,8,2
    • 2,8,1
    • 8,2,2
    Check

12. 12. What is the name of the element that has the electronic structure 2,8,3?

    • magnesium
    • aluminium
    • silicon
    • boron
    Check

13. 13. Fluorine has atomic number 9. What is its electronic structure?

    • 2,8,9
    • 7,2
    • 2,7
    • 9
    Check

14. 14. Use the Periodic Table. What is the atomic number for magnesium?

    • 12
    • 11
    • 13
    • 24
    Check

15. 15. Use the Periodic Table. What is the mass number for nitrogen?

    • 16
    • 12
    • 7
    • 14
    Check

16. 16. Use the Periodic Table. Which element has the atomic number 13?

    • magnesium
    • silicon
    • carbon
    • aluminium
    Check

17. 17. Use the Periodic Table. Which element has the mass number 20?

    • calcium
    • sodium
    • neon
    • fluorine
    Check

18. 18. Boron has atomic number 5 and mass number 11. How many neutrons does a boron atom have?

    • 5
    • 6
    • 11
    • 16
    Check

19. 19. Boron has atomic number 5 and mass number 11. How many electrons does a boron atom have?

    • 11
    • 16
    • 6
    • 5
    Check

20. 20. Carbon has atomic number 6 and mass number 12. How many protons does a carbon atom have?

    • 6
    • 3
    • 12
    • 18
    Check