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.

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

   • Agree: opposite charges sit together
   • Disagree: electrons are outside the whole atom
   • Disagree: electrons are around the nucleus
   • Agree: the nucleus holds the whole atom
4. 4.

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

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

5. Read this first

   Table (IUPAC data)

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

6. 5.

   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
   • Oxygen
   • Nitrogen, the next element
   • Still carbon, with mass number 13
7. 6.

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

   • Boron
   • Still carbon, since neutrons decide
   • Element 13, from the mass number
   • Nitrogen
8. 7.

   Atomic number, symbol, name. 16 S sulfur; 17 Cl chlorine; 19 K potassium. Atom X has 17 protons and 18 neutrons. Atom Y has 17 protons and 20 neutrons. What are they, Pia?

   • X is chlorine and Y is potassium
   • Both chlorine
   • Both sulfur
   • Two different elements, since neutrons differ
9. 8.

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

   • Particles spread evenly through the atom
   • Electrons drawn inside the nucleus
   • Protons and neutrons in the center, electrons around
   • Neutrons marked −, electrons marked +
10. 9.

    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 −
11. 10.

    A model shows a tiny nucleus and a wide cloud of electrons. Where is most of the mass, Zee?

    • Nowhere: atoms are empty
    • In the tiny nucleus
    • In the wide electron cloud
    • Shared evenly, since everything counts the same