Atomic Number Versus Atomic Mass
Chapter 2: The Chemical Basis of Life

To understand the relationship between atomic number and atomic mass, make a graph that compares these numbers for the first 20 elements. Look up the atomic masses in the periodic table on pages 944-945 in your textbook. Round the atomic masses to the nearest whole number. Plot atomic numbers on the x-axis of your graph and atomic masses on the y-axis. Choose a scale for the y-axis that will fit all the data. Place a point on the graph for each element from hydrogen to calcium and connect the points with a line.

Analyze the Data

---

1. What does your graph look like? What does it tell you about the relationship between atomic number and atomic mass?
2. Are there any points on the graph that do not seem to follow the pattern? Explain your answer.
3. What do you think your graph would look like if you plotted data for 92 elements?
4. Does your graph support using atomic numbers rather than atomic masses to organize the periodic table of the elements? Explain your answer.

TOP

Unit 1 Home Page