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