Grade 10 · Science · Chemistry

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

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

Grade 10 Science Worksheet - Challenge Me

NameDate

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

An ion has 12 protons, 12 neutrons and 10 electrons. What is its mass number, Ari?
An ion has 26 protons, 30 neutrons and 23 electrons. What is its mass number, Esme?
3.
A particle has 17 protons, 20 neutrons and 18 electrons. How is it written, Jun?
- Chlorine-37 with a 1+ charge
- Chlorine-37 with a 1− charge
- Argon-37, neutral
4.
A particle has 12 protons, 13 neutrons and 12 electrons. How is it written, Luz?
- Sodium-25 with a 1+ charge
- Magnesium-25, neutral
- Magnesium-37, neutral
5.
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
6.
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
7.
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
8.
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
9.
Argon-40 and calcium-40 have the same mass number. What differs, Tala?
- The color of their electrons
- Nothing differs between them
- Their numbers of protons
10.
A neutral atom has 15 protons. How many electrons does it have, Zee?
- 16
- 30
- 15

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

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

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

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.

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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