CK-12 Physical Science Concepts - For Middle School

http://www.ck12.org Chapter 2. Matter

• http://images.pcmac.org/SiSFiles/Schools/AL/BaldwinCounty/SpanishFortMiddle/Uploads/Forms/ANMNWo
  rksheet.pdf

Review

1. What is the atomic number of an atom? Why is this number important?


2. Describe the atomic mass unit. What does it represent and what does it equal?


3. The symbol below represents an isotope of helium. How many protons and neutrons does it have?

5

2 He

4. All carbon atoms have six protons. Most also have six neutrons, but some have seven or eight neutrons. What
   is the mass number of a carbon isotope that has seven neutrons?