Chapter 5
1. Draw the Lewis dot structures for the following elements:
a. X, an element from the Group IA family, 1 electron
b. Z, an element from the Group IIA family, 2 electrons
c. J, an element from the Group IVA family, 4 electrons
d. K, an element from the Group VIA family, 6 Electrons
2. Determine the chemical formulas for the following:
a. iron(III) sulfide, Fe forms a 3+ ion, S a 2- ion, Fe2S3
b. calcium hydride, Ca forms a 2+ ion, hydride is a 1- ion, CaH2
c. magnesium nitride, Mg forms a 2+ ion, nitride is a 3- ion, Mg3N2
d. aluminum fluoride, Al forms a 3+ ion, F forms a 1- ion, AlF3
3. Draw the Lewis dot structures for: (Note: make sure they satisfy the octet rule)
I
:
:
:
:
:
:
N
:
I
:
:
:
:
I
Valence Electrons (Group #) N: 5
Valence Electrons (Group #) I: 7
Total Valence Electrons: 26
:
:
:
:
: S : : C :: S :
:
:
:
:
: F : N :: N : F:
:
:
: :
: :
: :
H
: Cl : C : Cl :
H
Valence Electrons (Group #) C: 4
Valence Electrons (Group #) S: 6
Total Valence Electrons: 16
Valence Electrons (Group #) N: 5
Valence Electrons (Group #) F: 7
Total Valence Electrons: 24
Valence Electrons (Group #) C: 4
Valence Electrons (Group #) Cl: 7
Valence Electrons (Group #) H: 1
Total Valence Electrons: 20
4. a. Which bond is more polar, H-Cl or H-O?
EN Values: H: 2.1; Cl: 3.0; O: 3.5; Br: 2.8
HCl: EN = 3.0-2.1 = 0.9
HO: EN = 3.5-2.1 = 1.4, so H-O is more polar, larger EN value
b. Which of the following bonds is the most polar, that is, has the greatest ionic
character: H-Br, N-H, N-O, P-Cl?
EN Values: N: 3.0; P: 2.1
HBr: EN = 2.8-2.1 = 0.7
NH: EN = 3.0-2.1 = 0.9
NO: EN = 3.5-3.0 = 0.5
PCl: EN = 3.0-2.1 = 0.9
BOTH N-H and P-Cl are very polar.
5. Predict the types of bonds formed between each of the following pairs of elements:
a. sodium & sulfur, ionic
b. nitrogen & bromine, covalent
c. calcium & oxygen, ionic
d. carbon & oxygen, covalent
6. Explain why molecules of a perfume can be detected a few feet away from the person
wearing the perfume.
The gas molecules of the perfume vapor diffuse away from the person wearing the
perfume.
7. Which families are likely to form the following ions?
a. +1, 1A
b. –1, 7A
c. +2, 2A
d. –2, 6A
e. +3, 3A
f. –3, 5A
8. Represent the following structure showing the covalent bonds.
CO2
O=C=O