1. Ch. 3: “Atoms & the Periodic Table” Section 2: “A Guided Tour of the Periodic Table”

2. 1. Explain how you can determine the number of neutrons an atom has… Subtract the atomic number (Z) from the atomic mass (A). Subtract the atomic number (Z) from the atomic mass (A).

3. 2. Calculate how many neutrons a P-32 atom has. A - Z = 32 - 15 = 17 neutrons A - Z = 32 - 15 = 17 neutrons

4. 3. Name the element… a. lithium b. magnesium c. copper d. bromine e. helium f. sulfur g. sodium h. iron i. potassium

5. 4. Compare the number of valence electrons between O & Se. Are O & Se in the same period or group? Both elements have six valence electrons. They are in the same group/family but not the same period. Both elements have six valence electrons. They are in the same group/family but not the same period.

6. 5. Describe how a Na atom differs from a Na ion. Which form of Na is more likely to be found in nature? A Na atom is uncharged & has one valence electron. A Na ion is a Na atom that has lost its valence electron to become Na +. The ion is more often found in nature because the atom easily loses the valence electron to achieve an outmost energy level that resembles the noble gas Ne. A Na atom is uncharged & has one valence electron. A Na ion is a Na atom that has lost its valence electron to become Na +. The ion is more often found in nature because the atom easily loses the valence electron to achieve an outmost energy level that resembles the noble gas Ne.

7. 6. Predict which isotope of N is more commonly found, N-14 or N-15. Atomic mass is a weighted average of all the isotopes. The average atomic mass for N is 14.01 amu, so N-14 is more commonly found. Atomic mass is a weighted average of all the isotopes. The average atomic mass for N is 14.01 amu, so N-14 is more commonly found.

8. 7. Describe why the elements in the periodic table are arranged in order of increasing atomic number. When arranged according to atomic number, the properties of the elements repeat in a regular pattern. When arranged according to atomic number, the properties of the elements repeat in a regular pattern.

9. 8. Critical Thinking Scientists would predict that technetium would have the same properties as other elements in the same group, such as manganese or rhenium. Scientists would predict that technetium would have the same properties as other elements in the same group, such as manganese or rhenium.