Protons, neutrons and electrons
Grade 8 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
A sodium atom has atomic number 11 and mass number 23. Neutrons = mass number − atomic number. How many neutrons does it have, Ari?
An aluminum atom has atomic number 13 and mass number 27. Neutrons = mass number − atomic number. How many neutrons does it have, Bo?
A fluorine atom has atomic number 9 and mass number 19. Neutrons = mass number − atomic number. How many neutrons does it have, Esme?
Jun fills in a particle table. Which particle has a negative charge?
- The neutron
- The electron
- The proton
Where in an atom are the protons, Kira?
- Spread through the whole atom
- In the nucleus
- Circling outside the nucleus
Milo labels a drawing of a helium atom. Which letter marks an electron?
- Letter A, since electrons sit in the nucleus
- Letter C
- Letter B
In the same helium drawing, what is particle B, Noah?
Use the picture in question 6.
- A proton
- A neutron
- An electron inside the nucleus
A neutral carbon atom has 6 protons and 6 neutrons. How many electrons does it have, Ren?
- 12 electrons, the mass number
- 6 electrons
- 0 electrons, since they are tiny
A neutral oxygen atom has 8 protons. How many electrons balance its charge, Tala?
- 16 electrons, the mass number
- 8 electrons
- 4 electrons, half the protons
A neutral sodium atom has atomic number 11 and mass number 23. How many electrons, Zee?
- 11 electrons
- 12 electrons
- 23 electrons