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

NameDate

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

A calcium ion has 20 protons and a 2+ charge. How many electrons does it have, Ari?
A chloride ion has 17 protons and a 1− charge. How many electrons does it have, Bo?
An aluminum ion has 13 protons and a 3+ charge. How many electrons does it have, Esme?
Read this first
Atom diagram of a fluoride ion
9 protons and 10 neutrons in the nucleus, and 10 electrons in shells of 2 and 8. Notation: mass number 19 over atomic number 9, then F with a 1− charge.
4.
In the diagram, why is the fluoride ion's charge 1−, Jun?
- It has one more neutron than protons
- It lost a proton
- It has one more electron than protons
5.
In the diagram, how many neutrons does the fluoride ion have, Kira?
- 10
- 9
- 19
6.
In the diagram, why is this still fluorine, Luz?
- It gained a proton
- It still has 9 protons
- It has 10 electrons in it
7.
A sodium atom loses one electron. What does it become, Milo?
- A 1+ ion
- A new element
- A 1− ion
8.
An oxygen atom gains two electrons. What is its charge, Noah?
- 2+
- 2−
- No charge
9.
When an atom becomes an ion, which particles change in number, Pia?
- Electrons
- Protons
- Neutrons
10.
What do isotopes of one element share, Tala?
- The same atomic number
- The same number of neutrons
- The same mass number

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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