The Building Blocks of the Chemical World Electronic configurations
Part 1 Using materials provided by your teacher, use the information on page 178 to create Bohr atomic models of the elements shown in Fig. 10.3.3.
4 2
He
Part 2 Write the shorthand version of the electronic configuration for the same elements.
z Isotopes
The atoms of some elements can exist with different masses. The number of protons in the atoms of the element is the same, but the number of neutrons differ.
Atoms with the same number of protons but different numbers of neutrons are called isotopes. For example, carbon can have three isotopes.
z Fig. 10.3.4
The three possible isotopes of carbon
Carbon-12 (6 P + 6 N)
Comparing isotopes 1. In pairs, discuss what the atoms in Fig. 10.3.4 have in common.
2. Make a model of the nuclei of the three isotopes in Fig. 10.3.4. What materials would be most appropriate to use for these models?
3. Discuss how these atoms differ from each other.
4. You may have met one of these forms of carbon in your history class. Which one? Write a paragraph to explain how this isotope of carbon is useful to historians.
Isotopes of chlorine
Two isotopes of chlorine exist: Cl–35 and Cl–37. Using the periodic table, answer the following questions:
1. What is the atomic number of chlorine?
2. How many protons, neutrons and electrons does the isotope Cl–35 have?
3. How many protons, neutrons and electrons does the isotope Cl–37 have?
4. What do the two isotopes have in common? 179 5. How do the two isotopes differ?
6. Draw the Bohr model of the atom for each isotope.
7. Write out the electronic configuration for each isotope.
