Section 4.2 Molecular

Compounds

RECALL

Ionic Compounds:

consist of positive and negative ions, formed by the transfer of electrons from a metal to a non-metal

are electrolytes (conduct electricity when dissolved in water)

MOLECULAR COMPOUNDS

form when two non-metal atoms share electrons

the bond formed by the SHARING of electrons is called covalent bond

are non-electrolytes (do not conduct electricity when dissolved in water)

Diatomic Molecules

Diatomic molecules – made of two atoms

Hydrogen H2 (gas)

Nitrogen N2 (gas)

Fluorine F2 (gas)

Oxygen O2 (gas)

Iodine I2 (solid)

Chlorine Cl2 (gas)

Bromine Br2 (liquid)

HaveNoFear OfIceColdBeer

H1p0n

H1p0n the shared electrons

spend part of their time with one hydrogen nucleus and part of their time with the other nucleus

NOTE: one electron must come from each partner in the arrangement so that a PAIR is shared

LOSING an electron will leave H with no electrons

Consider two atoms of hydrogen

CARBON AND OXYGEN

C6p6n

O8p8n

Lewis Dot Diagrams

C O

CARBON AND OXYGEN

C O

Carbon has four electrons to share

Oxygen has two electrons to share

CARBON AND OXYGEN

these pairs are shared between the atoms

C OO

Valence Method

You can reach the same conclusion using the valence method used for ionic compounds C4+ O2-

C2 O4

CO2

1. Write the symbols2. Write the valence

above the atoms3. Criss-cross and reduce

(if necessary)4. Write out the formula

* doesn’t always work for molecular compounds

Naming Molecular Compounds

Use Greek prefixes to indicate the number of each type of atom in the compound

GREEK PREFIXES

1. mono 6. hexa2. di 7. hepta3. tri 8. octa4. tetra 9. nano5. penta 10.

deca

Naming Molecular Compounds

SOME RULES

use the Greek prefixes to represent the subscript in the final formula

“mono” is dropped if it applies to the first element listed

the ending of the second element is changed to “-ide”

Naming Molecular Compounds

CO2monocarbon dioxide

dropped

carbon dioxide

CO carbon monoxideCO

silicon tetrachloride

SiCl4

Nl3 nitrogen triiodide

Ban Dihydrogen MonoxideThe Invisible Killer

Dihydrogen monoxide is colorless, odorless, tasteless, and kills uncounted thousands of people every year. Most of these deaths are caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there. Prolonged exposure to its solid form causes severe tissue damage.

Symptoms of DHMO ingestion can include excessive sweating and urination, and possibly a bloated feeling, nausea, vomiting and body electrolyte imbalance. For those who have become dependent, DHMO withdrawal means certain death.

Dihydrogen monoxide:

is also known as hydroxyl acid, and is the major component of acid rain.

contributes to the "greenhouse effect." may cause severe burns. contributes to the erosion of our natural

landscape. accelerates corrosion and rusting of many

metals. may cause electrical failures and decreased

effectiveness of automobile brakes. has been found in excised tumors of terminal

cancer patients.

Contamination Is Reaching Epidemic Proportions!

Quantities of dihydrogen monoxide have been found in almost every stream, lake, and reservoir in America today. But the pollution is global, and the contaminant has even been found in Antarctic ice. DHMO has caused millions of dollars of property damage in the midwest, and recently California.

Despite the danger, dihydrogen monoxide is

often used:

as an industrial solvent and coolant. in nuclear power plants. in the production of styrofoam. as a fire retardant. in many forms of cruel animal research. in the distribution of pesticides. Even after

washing, produce remains contaminated by this chemical.

as an additive in certain "junk-foods" and other food products.

The Horror Must Be Stopped!

The American government has refused to ban the production, distribution, or use of this damaging chemical due to its "importance to the economic health of this nation."

In fact, the navy and other military organizations are conducting experiments with DHMO, and designing multi-billion dollar devices to control and utilize it during warfare situations. Hundreds of military research facilities receive tons of it through a highly sophisticated underground distribution network. Many store large quantities for later use.

Act NOW to prevent further contamination!

Find out more about this dangerous chemical.

What you don't know can hurt you and others

throughout the world.

How many people would like to sign a petition toban dihydrogen monoxide?

Homework Read p. 152- 158 Complete Q. 1-4 (p.156) “Molecular Compounds” WS#11