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

Answer Key - Grade 10 Science Worksheet - Challenge Me

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

1. 1.

   An ion has 17 protons, 20 neutrons and 18 electrons. What is its mass number, Bo?

   37
2. 2.

   An ion has 26 protons, 30 neutrons and 23 electrons. What is its mass number, Esme?

   56
3. 3.

   A particle has 17 protons, 20 neutrons and 18 electrons. How is it written, Jun?

   • Chlorine-37 with a 1− charge
   • Argon-37, neutral
   • Chlorine-37 with a 1+ charge
4. 4.

   A particle has 26 protons, 30 neutrons and 23 electrons. How is it written, Kira?

   • Iron-79, neutral
   • Iron-56 with a 3− charge
   • Iron-56 with a 3+ charge
5. 5.

   A particle has 12 protons, 13 neutrons and 12 electrons. How is it written, Luz?

   • Magnesium-37, neutral
   • Magnesium-25, neutral
   • Sodium-25 with a 1+ charge
6. 6.

   Milo says a sodium ion is no longer sodium because it lost an electron. Agree or disagree?

   • Disagree: it still has 11 protons
   • Agree: losing a particle changes the element
   • Agree: its proton left with the electron
7. 7.

   Noah says magnesium becomes 2+ by gaining two protons. Agree or disagree?

   • Agree: protons add charge
   • Disagree: it loses two electrons
   • Agree: nuclei grow in ions
8. 8.

   Pia says carbon-12 and carbon-14 are different elements. Agree or disagree?

   • Agree: the numbers differ
   • Disagree: both have 6 protons
   • Agree: their masses differ
9. 9.

   Na⁺ and F⁻ both have 10 electrons. Are they the same element, Ren?

   • Yes, once they are both neutral
   • Yes: same electrons, same element
   • No: they have different protons
10. 10.

    A neutral atom has 15 protons. How many electrons does it have, Zee?

    • 15
    • 30
    • 16