1) Metal character increases down a group and decreases across a period on the periodic table. Metals have low ionization energies and form cations by losing electrons. 2) Most metal oxides are basic, while most nonmetal oxides are acidic. When nonmetal oxides react with water, acids are formed. 3) The octet rule states that atoms bond to achieve a full outer shell of 8 electrons. Atoms gain, lose or share electrons to achieve an octet configuration.

1. KEY
GENERAL CHEMISTRY-I (1411)
S.I. # 31
1. Metal characteristic increases _______B_______ a group.
a. up b. down c. across
2. Metal character decreases _______C_______ a period.
a. up b. down c. across
3. Metals have ______B________ ionization energies.
a. high b. low c. zero d. positive e. negative
4. Group 1A metals for _____M+____ Ions and group 2A form ____M2+_____ions.
5. Most metal oxides are _____B______
a. acidic b. basic c. neutral
6. Most non metal oxides are: ____A______
a. acidic b. basic c. neutral
7. When nonmetal oxides react with water what is formed? An Acid
8. Complete and balance the following equations.
P4O10(s) + H2O(l)  4H3PO4(aq)
CO2(g) + H2O(l)  H2CO3(aq)
9. What are some properties of metalloids?
Metalloids have properties that are intermediate between metals and nonmetals.
Metalloids have found fame in the semiconductor industry.
10. Using only the periodic table, arrange the following atoms in increasing radius
(a) Cs, K, Rb K < Rb < Cs__________________
(b) In, Te, Sn Te < Sn < In_________________
(c) P, Cl, Sr Cl < P < Sr___________________
11. What is the octet rule?
Atoms will gain, lose or share electrons to achieve the nearest noble gas electron configuration.
Except for H and He, this corresponds to eight electrons in the valence shell, thus the term octet rule
12. How many electrons must a sulfur atom gain to achieve an octet in its valence
shell? S: [Ne]3s23p4 A sulfur atom has six valence electrons, so it must gain two
electrons to achieve an octet.
13. If an atom has the electron configuration 1s22s22p3, how many electrons must it
gain to achieve an octet?
1s22s22p3 = [He]2s22p3 The atom (N) has five valence electrons and must gain three
electrons to achieve an octet

2. KEY
14. a. Write the electron configuration for the element scandium, Sc.
Sc: 1s22s22p63s23p64s23d1 = [Ar]4s23d1
b. How many valence electrons does this atom possess?
Scandium has three (3) valence electrons.
c. What distinguishes these valence electrons from the other electrons in the
atom?
These valence electrons are available for chemical bonding, while the core
electrons do not participate in bonding.
15. Use Lewis symbols to represent the reaction that occurs between Mg and Br
atoms.
. . . . . .
. . . .
Mg +. Br . +. Br .  . Mg2+ + 2[ .Br. ] -
. . . . . . .
16. What ionic compound is expected to form from combination of the following
pairs of elements?
a. barium and oxygen BaO___________________
b. rubidium and iodine RbI ___________________
c. lithium and sulfur Li2S ___________________
d. bromine and magnesiumMgBr2___________________
17. Which of these elements is unlikely to form covalent bonds: S, H, K, Ar, Si?
Explain your choices
K and Ar. K is an active metal with one valence electron . It is most likely to achieve an octet by losing
this single electron and to participate in ionic bonding. Ar has a stable octet of valence electrons; it is not
likely to form chemical bonds of any type.
18. a.
What is the most electronegative element in group 6A? O_____
b.
Which is most electronegative out of Al, Si, P? P_____
c.
Which is most electronegative out of Ga, P, Cl, Na? Cl_____
d.
The element most likely to form an ionic compound with Ba out of
K, C, Zn, F F
19. Arrange the bonds in each of the following sets in order of increasing polarity:
a. C--F, O—F, Be—F O—F < C—F < Be—F
b. O—Cl, S—Br, C—P S—Br < C—P < O—Cl
c. C—S, B—F , N—O C—S < N—O < B—F
20. Does the octet rule apply to ionic as well as covalent compounds? Explain.
The octet rule applies to the individual ions in an ionic compound. A cation loses electrons and the anion
gains electrons to achieve an octet. For example: in MgCl2, Mg loses 2 e- to become Mg2+ with the
electron configuration of [Ne]. Each Cl atom gains one electron to form Cl- with the electron configuration
of [Ar].
21. Draw the Lewis structures for each of the following molecules or ions. Which
do not obey the octet rule?

3. KEY
a. CO2 b. IO3- c. BH3 d. BF4- e. XeF2
A and D