chem

Group 1 (Alkali Metals)

Highly reactive metals with 1 valence electron.

Group 2 (Alkaline Earth Metals)

Reactive metals with 2 valence electrons.

Group 17 (Halogens)

Very reactive nonmetals with 7 valence electrons.

Group 18 (Noble Gases)

Stable gases with a full outer shell of electrons.

Electronegativity (EN)

The tendency of an atom to attract shared electrons.

Nonpolar Covalent Bond

Bond with an EN difference of 0 < 0.4; involves equal sharing of electrons.

Polar Covalent Bond

Bond with an EN difference of -0.4 to 1.7; involves unequal sharing of electrons.

Ionic Bond

Bond with an EN difference greater than 1.7; involves electron transfer.

Boyle’s Law

P1 V1 = P2 V2; the pressure and volume of a gas are inversely related.

Charles’ Law

V1 /T1 = V2 /T2; the volume of a gas is directly proportional to its temperature.

Pressure-Temperature Law

P1 /T1 = P2 /T2; pressure is directly proportional to temperature.

Combined Gas Law

P1 V1 /T1 = P2 V2 /T2; combines Boyle’s, Charles’, and Pressure-Temperature Laws.

Ideal Gas Law

PV = nRT; relates pressure, volume, temperature, and number of moles.

Water Purification: Intake

Water is taken from a source and large debris is removed using a screen.

Water Purification: Coagulation and Flocculation

Special chemicals are added to make small particles clump together into larger flocs.

Water Purification: Sedimentation

Heavy clumps (flocs) sink to the bottom, clearing the water above.

Water Purification: Filtration

Water passes through filters made of sand, gravel, or charcoal to remove smaller particles.

Water Purification: Disinfection

Chemicals like chlorine are added to kill harmful microorganisms.

Water Purification: Storage

Clean water is stored in tanks until it is distributed for use.