Chapter 6:Inorganic and Organic Compounds

6.5

Chem 1110

Figures: Basic Chemistry 3rd Ed., Timberlake and Timberlake

Ionic vs. Covalent Bonding

Ionic Bonding Covalent Bonding

• Metal - nonmetal (NaCl)• Electron transfer and

electrostatic interactions• Formula Unit (from larger

arrays)• Solids

• Dissolve in water and conduct electricity

• Two nonmetals (O2, H2O)

• Electron sharing in bonds

• Discrete molecules

• All physical states (solid, liquid and gas)

• If they dissolve in water, they do not conduct electricity

The Covalent BondCovalent Bonding: a chemical bond that results from two nuclei attracting the same shared electron pair

Forming a H2 Molecule

• A covalent bond forms as two H atoms move close together to share electrons

Diatomic Elements

Several elements share electrons to form diatomic, covalent molecules:

Octet Rule

Covalent compounds also obey the Octet Rule:

• Each atom in the bond is seeking a noble gas configuration

• Electrons are shared to achieve the octet

• For Example:

Br → needs 1 electron to achieve an octet

Lewis Dot Structures

• We can use Lewis Dot structures to help us form Covalent Bonds:

H with Cl

H with O

P with Br

Electron-Dot Formulas

Electron-dot formulas:• the order of bonded atoms in a

covalent compound

• the bonding pairs of electrons between atoms

• the unshared (lone) valence electrons

• a central atom with an octet

Covalent Compounds

Bonding and Lone Pair Electrons

• Bonding pair of electrons are shared to create the covalent bond

• Non-bonding pair or lone pair make up the octet

Bonding and Lone Pair Electrons

• Bonding pair of electrons are shared to create the covalent bond

• Non-bonding pair or lone pair make up the octet

Cl2

HBr

H2S

Naming Covalent Compounds1) Most metallic atom comes first then the more

negative + “-ide”

For Example:

NO

NO2

N2O

2) Name includes the total number of each atom:

Table 6.10 (p. 178)

Naming Covalent Compounds

For Example:

SiBr4

P4O10

Naming Covalent Compounds

• Many covalent compounds have common names that you are most likely familiar with:

NH3

H2O

H2S

CH4

Formulas and Names of Some Covalent Compounds

Select the correct name for each compound:

A. SiCl4 1) silicon chloride2) tetrasilicon chloride3) silicon tetrachloride

B. P2O5 1) phosphorus oxide2) phosphorus pentoxide3) diphosphorus pentoxide

C. Cl2O7 1) dichlorine heptoxide2) dichlorine oxide3) chlorine heptoxide

Learning Check

Write the name of each covalent compound:

CO _____________________

CO2 _____________________

PCl3 _____________________

CCl4 _____________________

N2O _____________________

Learning Check