Protons, neutrons and electrons

Answer Key - Grade 8 Science Worksheet - Challenge Me

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

1. 1.

   Ari reads that an iron atom has mass number 56 and 30 neutrons. How many protons does it have?

   26 protons
2. 2.

   Bo reads that a copper atom has mass number 63 and 34 neutrons. How many protons does it have?

   29 protons
3. 3.

   Esme reads that a boron atom has mass number 11 and 6 neutrons. How many protons does it have?

   5 protons
4. 4.

   Jun says electrons sit inside the nucleus, next to the protons. Agree or disagree?

   • Disagree: electrons are around the nucleus
   • Disagree: electrons are outside the whole atom
   • Agree: opposite charges sit together
   • Agree: the nucleus holds the whole atom
5. 5.

   Kira says a neutron has a small positive charge. Agree or disagree?

   • Disagree: it has no charge
   • Agree: it sits with the protons
   • Agree: it is a weak proton
   • Disagree: it is negative
6. 6.

   Luz says an electron has about the same mass as a proton, since their charges balance. Agree or disagree?

   • Disagree: an electron is far lighter
   • Agree: equal charges mean equal mass
   • Disagree: an electron is heavier
   • Agree: both are particles in one atom

7. Read this first

   Table (IUPAC data)

   Atomic number, symbol, name. 5 B boron; 6 C carbon; 7 N nitrogen; 8 O oxygen.

8. 7.

   A carbon atom has 6 protons and 6 neutrons. If it had one more neutron, what would it be, Milo?

   • Boron, since it is heavier
   • Nitrogen, the next element
   • Oxygen
   • Still carbon, with mass number 13
9. 8.

   Imagine the same carbon atom with one more proton instead. Using the table, what would it be, Noah?

   • Nitrogen
   • Still carbon, since neutrons decide
   • Boron
   • Element 13, from the mass number
10. 9.

    Ren checks three classmates' atom models. Which one is right?

    • Neutrons marked −, electrons marked +
    • Electrons drawn inside the nucleus
    • Particles spread evenly through the atom
    • Protons and neutrons in the center, electrons around
11. 10.

    Tala labels an atom model's key. Which set of labels is right?

    • Proton +, neutron no charge, electron −
    • Proton +, neutron −, electron −
    • Proton +, neutron +, electron −
    • Proton −, neutron no charge, electron +