CK-12 Physical Science Concepts - For Middle School

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

FIGURE 2.53

1. How is the hydrogen atom different from the atoms of all the other elements that are represented by the
   animated models?


2. Which circles represent protons in the atomic models? The red circles or the blue circles? Explain how you
   know.


3. Based on all of the models, what might you infer about the way electrons move around the nucleus of an atom?

Review

1. What is an atom?


2. Which of the following statements is true about the atoms of any element?
   a. They have the same number of protons as the atoms of all other elements.
   b. They have protons that are identical to the protons of all other elements.
   c. They have the same size as the atoms of all other elements.
   d. They have the same number of protons as neutrons.


3. Explain why atoms are always neutral in charge.