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Grade 9 · Science · Unit 4 of 11

Inside the Atom

Particles, models and shells

What your child practises

Protons, neutrons and electrons, how Dalton, Thomson, Rutherford and Bohr's models changed with evidence, atomic and mass numbers, and drawing the electron shells of the first 20 elements.

New Brunswick Curriculum skill descriptor: Scientific Literacy: Sensemaking · the parts of an atom

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A neutral atom has electrons arranged 2, 4. How many protons are in its nucleus?

    answer box

  2. Question 2

    Which particle has a mass that is very small compared with the others?

    • electron
    • neutron
    • nucleus
    • proton

  3. Question 3

    A neutral atom has the same number of…

    • protons and neutrons
    • protons and electrons
    • neutrons and electrons
    • shells and protons

  4. Question 4

    Carbon-12 and carbon-14 both have 6 protons. How do they differ?

    • They have different numbers of shells
    • They have different numbers of neutrons
    • They are different elements
    • They have different numbers of protons

  5. Question 5

    An atom's mass number is the number of…

    • protons plus neutrons
    • protons only
    • shells
    • electrons only

  6. Question 6

    Which shows the electrons in each shell (Bohr–Rutherford) of a neutral lithium atom (atomic number 3)?

    • 2
    • 2, 3
    • 2, 2
    • 2, 1

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