Properties of Nuclei
12.1 Properties of Nuclei
Learning Objectives
- Describe the composition and size of an atomic nucleus
- Use a nuclear symbol to express the composition of an atomic nucleus
- Explain why the number of neutrons is greater than protons in heavy nuclei
- Calculate the atomic mass of an element given its isotopes
Practice!
| Practice 12.1.1 |
|---|
How many protons and neutrons does a nucleus designated as  contain? |
| A. 20 neutrons and 20 protons |
| B. 22 protons and 18 neutrons |
| C. 18 protons and 22 neutrons |
| D. 18 protons and 40 neutrons |
| E. 40 protons and 18 neutrons |
| Practice 12.1.2 |
|---|
| Iron has atomic number 26. Naturally mined iron contains isotopes of mass numbers 54, 56, 57, and 58. Which of the following statements is FALSE? |
| A. Every atom of iron has 26 protons |
| B. Some iron atoms have 30 neutrons |
| C. Some iron atoms have 54 neutrons |
| D. The isotopes may be separated in a mass spectrometer |
| E. There are four kinds of naturally occurring iron atoms with the same chemical properties |
Practice!
| Practice 12.1.3 |
|---|
| The nucleus of an atom has a radius of 5.61 × 10–15 m. If the nucleus contains 45 protons, how many neutrons does the nucleus contain? |
| A. 45 |
| B. 57 |
| C. 69 |
| D. 84 |
| E. 102 |
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