1. Chapter 4 Compounds and Their Bonds
4.5
Covalent Compounds
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

2. Covalent Bonds Covalent bonds form
when atoms share electrons to complete octets.
between two nonmetal atoms.
between nonmetal atoms from Groups 4A(14), 5A(15), 6A(16), and 7A(17).

3. Hydrogen Molecule A hydrogen molecule
is stable with two electrons (helium).
has a shared pair of electrons.

4. Forming Octets in Molecules
In a fluorine, F2,, molecule, each F atom
shares one electron.
attains an octet.

5. Carbon forms 4 covalent bonds
In a CH4, methane, molecule
a C atom shares 4 electrons to attain an octet.
each H shares 1 electron to become stable like helium.

6. Multiple Bonds In nitrogen molecule, N2,
each N atom shares 3 electrons.
each N attains an octet.
the bond is a multiple bond called a triple bond.
the name is the same as the element.

7. Naming Covalent Compounds
To name covalent compounds
STEP 1: Name the first nonmetal as an element.
STEP 2: Name the second nonmetal with an ide ending.
STEP 3: Use prefixes to indicate the number of atoms (subscript) of each element.
Table4.12

8. Naming Covalent Compounds
What is the name of SO3?
1. The first nonmetal is S sulfur.
2. The second nonmetal is O named oxide.
3. The subscript 3 of O is shown as the prefix tri.
SO3  sulfur trioxide
The subscript 1 (for S) or mono is understood.

9. Naming Covalent Compounds
Name P4S3.
1. The first nonmetal P is phosphorus.
2. The second nonmetal S is sulfide.
3. The subscript 4 of P is shown as tetra.
The subscript 3 of O is shown as tri.
P4S3  tetraphosphorus trisulfide

10. Formulas and Names of Some Covalent Compounds
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

11. Learning Check Select the correct name for each compound.
A. SiCl4 1) silicon chloride
2) tetrasilicon chloride
3) silicon tetrachloride
B. P2O5 1) phosphorus oxide
2) phosphorus pentoxide
3) diphosphorus pentoxide
C. Cl2O7 1) dichlorine heptoxide
2) dichlorine oxide
3) chlorine heptoxide

12. Solution Select the correct name for each compound.
A. SiCl4 3) silicon tetrachloride
B. P2O5 3) diphosphorus pentoxide
C. Cl2O7 1) dichlorine heptoxide

13. Learning Check Write the name of each covalent compound.
PCl3 _____________________
CCl4 _____________________
N2O _____________________

14. Solution Write the name of each covalent compound. CO carbon monoxide
CO2 carbon dioxide
PCl3 phosphorus trichloride
CCl4 carbon tetrachloride
N2O dinitrogen monoxide

15. Guide to Writing Formulas
The prefixes in the name are used to write the formula.
STEP 1: Write the symbols in the order of the elements in
the name.
STEP 2: Write any prefixes as subscripts.
Example: Write the formula for carbon disulfide.
STEP 1: Elements are C and S
STEP 2: No prefix for carbon means 1 C
Prefix di = 2
Formula: CS2

16. Learning Check Write the correct formula for each of the following.
A. phosphorus pentachloride
B. dinitrogen trioxide
C. sulfur hexafluoride

17. Solution
Write the correct formula for each of the following.
A. phosphorus pentachloride
1 P penta = 5 Cl PCl5
B. dinitrogen trioxide
di = 2 N tri = 3 O N2O3
C. sulfur hexafluoride
1 S hexa = 6 F SF6

18. Learning Check
Identify each compound as ionic or covalent and give its
correct name.
A. SO3
B. BaCl2
C. (NH4)3PO4
D. Cu2CO3
E. N2O4

19. Solution Identify each compound as ionic or covalent and give its
correct name.
A. SO3 covalent – sulfur trioxide
B. BaCl2 ionic – barium chloride
C. (NH4)3PO3 ionic – ammonium phosphite
D. Cu2CO3 ionic – copper(I) carbonate
E. N2O4 covalent – dinitrogen tetroxide

20. Learning Check Name the following compounds. A. Ca3(PO4)2 B. FeBr3
C. SCl2
D. Cl2O
E. N2

21. Solution Name the following compounds.
A. Ca3(PO4)2 ionic Ca2+ PO43− calcium phosphate
B. FeBr3 ionic Fe3+ Br − iron(III) bromide
C. SCl covalent 1S 2 Cl sulfur dichloride
D. Cl2O covalent 2 Cl 1 O dichlorine monoxide
E. N covalent 2N(element) nitrogen

22. Learning Check Write the formulas for the following.
A. calcium nitrate
B. boron trifluoride
C. aluminum carbonate
D. dinitrogen tetroxide
E. copper(I) phosphate

23. Solution Write the formulas for the following.
A. calcium nitrate Ca2+, NO3− Ca(NO3)2
B. boron trifluoride B, 3 F BF3
C. aluminum carbonate Al3+, CO32− Al2(CO3) 3
D. dinitrogen tetroxide N, 4 O N2O4
E. copper(I) phosphate Cu+, PO43− Cu3PO4