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Year 10 Science — Inside the atom

Count protons, neutrons and electrons from an atomic number and a mass number, fill the shells and read off a valency, and say what makes two atoms isotopes.

Name: ________________________

  1. 1.This atom has electrons in three shells. Tap its valence shell.

    Write the number of the part.

    1234

  2. 2.Using the rule that a shell numbered n holds at most 2n² electrons, what is the greatest number the M shell, where n is 3, can hold? Answer with a number.

  3. 3.Oxygen's electronic configuration is 2, 6. What is its valency? Answer with a number.

  4. 4.An atom has 17 protons and 18 neutrons. What is its mass number? Answer with a number.

  5. 5.Nitrogen's electronic configuration is 2, 5. What is its valency? Answer with a number.

  6. 6.Two atoms have the same atomic number but different mass numbers. What are they called?

    • a) Ions of the same element
    • b) Isotopes of the same element
    • c) Two molecules of one compound
    • d) Two different elements

  7. 7.Which number decides which element an atom belongs to?

    • a) The number of protons in its nucleus
    • b) The number of neutrons in its nucleus
    • c) The number of shells its electrons occupy
    • d) The number of nucleons in its nucleus

  8. 8.Why do the isotopes of an element behave the same way chemically?

    • a) They have the same number of neutrons
    • b) They have the same number of electrons, arranged the same way
    • c) They have the same mass number
    • d) They have the same melting and boiling points

Answer key — Year 10 Science — Inside the atom

  1. 1. 4 — The furthest ring
  2. 2. 18
  3. 3. 2
  4. 4. 35
  5. 5. 3
  6. 6. b) Isotopes of the same element
  7. 7. a) The number of protons in its nucleus
  8. 8. b) They have the same number of electrons, arranged the same way