Name ____________________________________ Date ______________ P___R___S___
Honors Chemistry
Electron Configuration and Reactivity Practice KEY
1 a) Write the electron configuration for oxygen and sulfur.
Oxygen (8): 1s2 2s2 2p4
Sulfur (16): 1s2 2s2 2p6 3s2 3p4
1 b) Compare and contrast where oxygen and sulfur are placed on the periodic table.
Oxygen: group 6, period 2
Sulfur: group 6, period 3
1 c) Using the electron configurations in part (a), compare the chemical reactivities of oxygen and sulfur.
Explain your answer.
Oxygen is more chemically reactive than sulfur because it only has 2 electron shells while sulfur has 3 electron shells. Both oxygen and sulfur has 6 valence electrons and need to gain two more electrons to get full set of 8. Since oxygen has only 2 shells, there is more attractive force between the nucleus and the outermost shell, so it is easier for oxygen to attract the electrons and hold tightly. Sulfur has 3 shells, there is less attractive force between the nucleus and the outermost shell, so it is more difficult for sulfur to attract the electrons and hold tightly.
1 d) Identify an element that would have a chemical reactivity similar to that of sulfur.
Explain your answer.
Selenium has a similar chemical reactivity as sulfur. They both have 7 valence electrons and need to gain 2 more electrons to get full set of 8 electrons.

Name ____________________________________ Date ______________ P___R___S___
Honors Chemistry
Electron Configuration and Reactivity Practice
2 a) Write the electron configuration for argon and potassium.
Argon (18): 1s2 2s2 2p6 3s2 3p6
Potassium (19): 1s2 2s2 2p6 3s2 3p6 4s1
2 b) Compare and contrast where argon and potassium are placed on the periodic table.
Argon: group 18, period 3
Potassium: group 1, period 4
2 c) Using the electron configurations in part (a), compare the chemical reactivities of argon and potassium.
Explain your answer.
Potassium is more chemically reactive than argon because it is less stable than argon. Argon has 8 valence electrons that is already full set of electrons, so it does not need to gain or lose electrons anymore.
Potassium has 1 valence electron and needs to lose that electron to get full set of 8 valence electrons, so it will react with an element that has an electron to accept.
2 d) Identify an element that would have a chemical reactivity similar to that of potassium.
Explain your answer.
Sodium will have similar chemical reactivity as potassium. They both have 1 valence electron and need to lose that one electron to get full set of 8.

Name ____________________________________ Date ______________ P___R___S___
Honors Chemistry
Electron Configuration and Reactivity Practice
3 a) Write the electron configuration for magnesium and calcium.
Magnesium (12): 1s2 2s2 2p6 3s2
Calcium (20): 1s2 2s2 2p6 3s2 3p6 4s2
3 b) Compare and contrast where magnesium and calcium are placed on the periodic table.
Magnesium: group 2, period 3
Calcium: group 2, period 4
3 c) Using the electron configurations in part (a), compare the chemical reactivities of magnesium and
calcium.
Explain your answer.
Calcium is more chemically reactive than magnesium. Both calcium and magnesium have 2 valence electrons and need to lose these 2 electrons to get full set. However, Calcium has 3 shells and the attractive force between the nucleus and the outermost shell is less, so it is easier for calcium to lose the valence electrons. Magnesium has 2 shells and the attractive force between the nucleus and the outermost shell is more, so it is more difficult for magnesium to lose the valence electrons.
3 d) Identify an element that would have a chemical reactivity similar to that of calcium.
Explain your answer.
Beryllium has a similar chemically reactivity as calcium. They both have 2 valence electrons and need to lose these 2 electrons to get full set of electrons.

Name ____________________________________ Date ______________ P___R___S___
Honors Chemistry
Electron Configuration and Reactivity Practice
4 a) Write the electron configuration for argon and nitrogen.
Argon (18): 1s2 2s2 2p6 3s2 3p6
Nitrogen (7): 1s2 2s2 2p3
4 b) Compare and contrast where argon and nitrogen are placed on the periodic table.
Argon: group 18, period 3
Nitrogen: group 15, period 2
4 c) Using the electron configurations in part (a), compare the chemical reactivities of argon and nitrogen.
Explain your answer.
Nitrogen is more chemically reactive than argon because it is less stable than argon. Argon has 8 valence electrons that is already full set of electrons, so it does not need to gain or lose electrons anymore.
Nitrogen has 5 valence electron and needs to gain 3 more electrons to get full set of 8 valence electrons, so it will react with an element that has electrons to donate.
4 d) Identify an element that would have a chemical reactivity similar to that of nitrogen.
Explain your answer.
Phosphorus will have similar chemical reactivity as Nitrogen. They both have 5 valence electrons and need to gain 3 more electrons to get full set of 8.