Chapter 12

The Periodic Table

Section 2 – Grouping the Elements

Essential Questions

Why do elements in a group have similar characteristics? (12-2)

What are the properties of the elements in each group of the periodic table? (12-2)

Grouping the Elements

Properties of a group of elements are similar

Atoms have the same number of electrons in the outer energy level

Group 1: Alkali Metals

Group contains: metals

Electrons in outer level: 1

Reactivity: very reactive

Other shared properties: softness, color of silver, shininess, low density

Used for: flavoring food (sodium chloride - table salt), photography (potassium bromide)

Group 2: Alkaline-Earth Metals

Group contains: metals

Electrons in outer level: 2

Reactivity: very reactive, but less than group 1

Other shared properties: color of silver, higher density than alkaline metals

Used for: airplane-making compounds, cement, chalk

Groups 3-12: Transition Metals

Group contains: metals

Electrons in out level: 1 or 2

Reactivity: less reactive than alkaline-earth metals

Other shared properties: shininess, good conductors of thermal and electric energy; higher densities and melting points

Lanthanides and Actinides

Lanthanides are Period 6 transition metals

Shiny, reactive

Used to make steel

Actinides are Period 7 transition metals

All are radioactive

All are man-made in laboratories

Group 13: Boron Group

Group contains: 1 metalloid & 5 metals

Electrons in out level: 3

Reactivity: reactive

Other shared properties: solids at room temperature

Used for: auto parts, aluminum foil, cans, siding

Group 14: Carbon Group

Group contains: 1 nonmetal; 2 metalloids; 3 metals

Electrons in out level: 4

Reactivity: varies among elements

Other shared properties: solids at room temperature

Used for: compounds necessary for life (proteins, fats, carbohydrates), tin

Group 15: Nitrogen Group

Group contains: 2 nonmetals, 2 metalloids, 2 metals

Electrons in out level: 5

Reactivity: varies among the elements

Other shared properties: solids at room temperature (except for nitrogen)

Used for: nitrogen is about 80% of air you breathe, also used for fertilizer

Group 16: Oxygen Group

Group contains: 3 nonmetals; 1 metalloid; 1 metal

Electrons in out level: 6

Reactivity: reactive

Other shared properties: solids at room temperature, except oxygen

Used for: oxygen is 20% of air you breathe; sulfur is used in industry

Group 17: Halogens

Group contains: nonmetals

Electrons in out level: 7

Reactivity: very reactive

Other shared properties: poor conductors of electricity; violent reactions with alkali metals

Used for: readily combine with other atoms to form salts, and cleaning agents

Group 18: Noble Gases

Group contains: nonmetals

Electrons in out level: 8 (except helium, which has 2)

Reactivity: unreactive

Other shared properties: colorless, odorless gases at room temperature

Used for: (very useful) lights, floatation

Hydrogen

Group contains: ONLY Hydrogen

Electrons in out level: 1

Reactivity: reactive

Other properties: colorless, odorless gas at room temperature, low density, explosive reaction w/ oxygen

Used for: fuel in rockets; most abundant element in universe