Catalyst:• Begin working on the handout at the front.• Make sure you look up the definition of Lewis Dot Diagrams!

Groups or Families• The physical and chemical properties of elements repeat in a

predictable way when atomic numbers are used, this is called periodic law.

Comparison of Groups (Families)

Similarities Differences

Chemical properties Total number of electrons

Number of valence electrons Atomic mass

Charge Reactivity

Classes of Elements

• Three ways to classify the elements:1. Solids, liquids, and gases based on state at room temp2. Those that occur naturally and those that do not3. Metals, nonmetals, or metalloids (based off of general properties)

Metal Nonmetal Metalloid

Metals

Properties• Good conductors of

electricity and heat

• Solids at room temp (except for mercury)

• Most are malleable (can be shaped)

Palladium

Mercury

Metals

• Many are ductile (can be drawn into thin wires)

• Some are very reactive

• Some do not react easily

Sodium and Water

Lithium and Water

Nonmetals• Poor conductors of

heat and electricity

• Low boiling points

• Many are gases at room temp

Nonmetals

• Solid nonmetals at room temp are brittle

• Broad range of reactivity Sulfur

Metalloids

• Properties fall between metals and nonmetals

• Ability to conduct electricity varies with temp

Silicon

Germanium

Group 1: Alkali Metals

• Single valence electron (+1)

• Contains Li, Na, K, Rb, Cs, Fr

• Like to give away e-• Very reactive• Found in nature only as

compounds

EXAMPLE: Table Salt (Na + Cl)

Group 2: Alkaline Earth Metals

• Two valence electrons (+2)

• Contains Be, Mg, Ca, Sr, Ba, Ra

• Like to give away e-• Harder than group 1• Reactivity is temp

dependent• Important for biological

functions

Calcium important for bones

Magnesium plays key role in photosynthesis of green

leafy plants

Group 3: Boron Family

• Three valence electrons (+3)

• Contains metalloid Boron and Al, Ga, In, Tl

• Contains Aluminum- most abundant metal in Earth’s crust

• Aluminum used for many things

Gutters

Window Frames

Airplanes

Group 4: Carbon Family• Four valence electrons (+4)• Group contains nonmetal

(C), two metalloids (Si/Ge), & two metals (Sn/Pb)

• Metallic nature increases from top to bottom

• Except for H2O, most of the compounds in body contain Carbon

Silicon in form of SiO2

Silicon carbide on saw blades makes longer

lasting

Group 7: Halogens

• 7 valence electrons

• Highly reactive nonmetals

• Contains F, Cl, Br, I, At

• Though physically different they’re very similar chemically

Chlorine used to kill bacteria in pools

Fluoride in toothpaste to prevent tooth decay

Seafood is a good source of iodine

Group 8: The Noble Gases• Outer shell of electron

cloud is full• 8 valence electrons

except for He (2)• Colorless and odorless• Extremely unreactive• Used in “neon” lights