BRAINJOY / STUDENT 1 OF 2

Atoms and isotopes

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Find the particle clues. Circle one answer or write the requested number. Explain your reasoning to a partner after you finish.

1. Which particle is uncharged?

  • A. Proton
  • B. Neutron
  • C. Electron

2. A neutral carbon atom has 6 protons. How many electrons does it have? Enter digits only.

3. An atom has atomic number 8 and mass number 18. How many neutrons does it have? Enter digits only.

4. Carbon-12 and carbon-13 have different numbers of protons.

  • A. True
  • B. False

5. An atom has 7 protons and 8 neutrons. What is its mass number?

  • A. 1
  • B. 7
  • C. 8
  • D. 15

6. Which particle number identifies an element?

  • A. Proton number
  • B. Neutron number
  • C. Electron number alone
  • D. Protons plus electrons

Particle detectives / STUDENT 1 OF 2 / BrainJoy
Original BrainJoy. Free for own classroom/home use. Not for resale. Teacher review required.

BRAINJOY / STUDENT 2 OF 2

Follow the charge clues

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Use these clues for single atoms and monatomic ions: mass number = protons + neutrons; charge in elementary-charge units = protons - electrons.

7. A sodium ion has 11 protons and a charge of +1. How many electrons does it have? Enter digits only.

8. A chloride ion has 17 protons and a charge of -1. How many electrons does it have? Enter digits only.

9. In ordinary ion formation by electron transfer, the proton number stays the same.

  • A. True
  • B. False

10. Which pair represents isotopes of the same element? Each pair is written as (protons, neutrons).

  • A. (6, 6) and (7, 6)
  • B. (8, 8) and (8, 10)
  • C. (11, 12) and (12, 11)
  • D. (3, 4) and (4, 3)

11. A magnesium-24 ion has 12 protons and a charge of +2. How many electrons does it have? Enter digits only.

12. A learner says: "A positive ion has gained positive protons." For ordinary ion formation by electron transfer, what is the better explanation?

  • A. It lost negative electrons.
  • B. It gained negative electrons.
  • C. Every neutron became a proton.
  • D. Its mass number must become zero.

Particle detectives / STUDENT 2 OF 2 / BrainJoy
Original BrainJoy. Free for own classroom/home use. Not for resale. Teacher review required.