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10th grade Count protons, neutrons and electrons in atoms, ions and isotopes worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

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Count protons, neutrons and electrons in atoms, ions and isotopes

Grade 10 Science Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

  1. A sodium atom has mass number 23 and atomic number 11. How many neutrons are in its nucleus, Ari?

  2. A chlorine atom has mass number 35 and atomic number 17. How many neutrons are in its nucleus, Bo?

  3. An iron atom has mass number 56 and atomic number 26. How many neutrons are in its nucleus, Esme?

  4. Read this first

    Atom diagram with nuclear notation

    Magnesium-24. The nucleus holds 12 protons and 12 neutrons; 12 electrons sit in shells of 2, 8 and 2. Beside it: mass number 24 written over atomic number 12, then Mg.

  5. In the diagram, what is magnesium's atomic number, Jun?

    • 24
    • 12
    • 2

  6. In the diagram, why is the mass number 24, Kira?

    • 12 protons + 12 electrons
    • 2 + 8 + 2 electrons
    • 12 protons + 12 neutrons

  7. Which particle's count decides what element an atom is, Milo?

    • Neutrons
    • Electrons
    • Protons

  8. Which particle has no charge, Noah?

    • The electron
    • The proton
    • The neutron

  9. In nuclear notation, what does the top number show, Ren?

    • The atomic number
    • The charge
    • The mass number

  10. In nuclear notation, what does the bottom number show, Tala?

    • The number of neutrons
    • The mass in grams
    • The number of protons

  11. What does the 14 in carbon-14 tell you, Zee?

    • Its mass number
    • Its number of electrons
    • Its atomic number
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10th grade Count protons, neutrons and electrons in atoms, ions and isotopes worksheet – printable
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About this worksheet

Count protons, neutrons and electrons in atoms, ions and isotopes. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can read nuclear notation: mass number over atomic number, then the symbol and any charge.
  • I can count protons, neutrons and electrons in atoms, ions and isotopes.
  • I can explain that ions form by gaining or losing electrons, so the element stays the same.
  • I can write the notation for a particle from its counts.

Standard: supports HS-PS1-1

Words to know

atomic number: The number of protons; it decides the element

mass number: Protons + neutrons

ion: An atom that has gained or lost electrons, so it has a charge

isotope: Atoms of one element with different numbers of neutrons

nuclear notation: Mass number over atomic number beside the symbol

Common mistakes

Your child added the two numbers. Neutrons = mass number − atomic number.

Your child added the charge. A positive ion has lost electrons, so electrons = protons − charge.

Your child counted the electrons in the mass number. Electrons are so light that the mass number counts only protons and neutrons.

Questions parents ask

What is the most common mistake with count protons, neutrons and electrons in atoms, ions and isotopes?

Your child added the two numbers. Neutrons = mass number − atomic number.

Are these 10th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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