Chapter 6: The Periodic Table and Periodic Trends
6.1 Development of the Modern Periodic Table
Practice Problems
Match each element in Column A with the best matching description from Column B. Each Column A element may
match more than one description from Column B.
Column A
Column B
1. strontium
a. halogen
2. chromium
b. noble gas
3. iodine
c. alkaline earth metal
4. nitrogen
d. metalloid
5. argon
e. alkali metal
6. rubidium
f. representative element
7. silicon
g. transition element
Classification of the Elements
Practice Problems
Use the periodic table to answer the following questions.
8. How many valence electrons are in an atom of each of the following elements?
a. magnesium
d. arsenic
b. selenium
e. iodine
c. tin
9. In which energy level are the valence electrons of the elements listed in question 8?
10. Identify each of the following elements.
a. an electron configuration of [Kr]5s24d105p2
b. five valence electrons in the sixth energy level
c. two valence electrons in the first energy level
d. three fewer electrons in the fourth energy level than krypton
e. an electron configuration ending in 4p2
Practice Problems
11. Without using the periodic table, determine the group, period, and block in which an element with each of the
following electron configurations is found.
a. [He]2s22p5
c. [Kr]5s24d105p3
2
b. [Ar]4s
d. [Ar]4s23d3
12. Write the electron configuration of the following elements.
a. the alkaline earth element in the sixth period
b. the halogen in the third period
c. the group 14 element in the third period
d. the group 5 element in the fourth period
e. the group 1 element in the fifth period
6.3 Periodic Trends
Practice Problems
13. For each of the following pairs, predict which atom is larger.
a. Mg, Sr
d. Ge, Br
b. Sr, Sn
e. Cr, W
c. Ge, Sn
14. Comparing elements from left to right across a period, what general trend would you predict for the energy required
to remove a valence electron from an atom? Explain the basis for your prediction.
In the following questions, the charges of ions are indicated by the superscript numbers and signs.
15. For each of the following pairs, predict which atom or ion is larger.
a. Mg, Mg2
d. Cl, I

b. S, S2
e. Na, Al3
c. Ca2, Ba2


16. Predict which of the ions, Mg2 or S2 , is larger. Explain your prediction.
Practice Problems
17. For each of the following pairs, predict which atom has the higher first ionization energy.
a. Mg, Na
d. Cl, I
b. S, O
e. Na, Al
c. Ca, Ba
f. Se, Br
18. For each of the following pairs, predict which atom forms a positive ion more easily.
a. Be, Ca
d. K, Ca
b. F, I
e. Sr, Sb
c. Na, Si
f. N, As
Practice Problems
19. For each of the following elements, state whether it is more likely to gain or lose electrons to form a stable octet
configuration and how many electrons will be gained or lost.
a. K
e. Al
b. Br
f. I
c. O
g. Ar
d. Mg
20. Which noble-gas configuration is each of the following elements most likely to attain by gaining or losing electrons?
a. S
e. Fr
b. Sr
f. N
c. Cl
g. Ba
d. Be
Practice Problems
21. For each of the following pairs, predict which atom has the higher electronegativity.
a. Mg, Na
d. Ca, Ba
b. Na, Al
e. S, O
c. Cl, I
f. Se, Br
Chapter 6 Review
22. Explain why the word periodic is applied to the table of elements.
23. Why do elements in a group in the periodic table exhibit similar chemical properties?
24. What chemical property is common to the elements in group 18 of the periodic table? Why do these elements have
this property?
25. In terms of electron configurations, what does the group number of the representative elements in the periodic table
tell you?
26. Describe the group and period trends in the following atomic properties.
a. atomic radius
b. electronegativity
c. first ionization energy
d. ionic radius
27. Describe the relationship between the electronegativity value of an element and the tendency of that element to gain
or lose electrons when forming a chemical bond.