1. Groups of the Periodic Table
Aim PT3 – what are the characteristics of the different groups (also known as FAMILIES) in the Periodic Table?

2. Hydrogen Hydrogen belongs to a family of its own.
Hydrogen is a diatomic reactive gas.
Diatomic molecule are elements that occur in nature in pairs - Br I N Cl H O F
Remember the Hindenburg!
Hydrogen is promising as an alternative fuel for automobiles

3. Group 1 - Alkali Metals
1st column on the periodic table (Group 1) not including hydrogen
One (1) electron in valence shell
Very reactive metals, always combined with something else in nature (like in salt) (go to vid)
Soft enough to cut with a butter knife
Examples
Lithium (Li)
Sodium (Na)
Potassium (K)

4. Group 2 Alkaline Earth Metals
Two (2) electrons in valence shell
Reactive metals that are always combined with nonmetals in nature
Several of these elements are important mineral nutrients
Examples:
Magnesium (Mg)
Calcium (Ca)

5. Group 3 – 12 - Transition Metals
All have mobile electrons
Two outer shells allow electrons to move back and forth between them
allows heat and electricity to pass through metals easily
Less reactive, harder metals than Group 1 or 2
Form colored solutions when mixed with water
High melting points
Includes metals used in jewelry and construction

6. Group 13 - Boron Family Three (3) electrons in valence shell Examples
Aluminum metal was once rare and expensive, not a “disposable metal”
Boron – used in nuclear fission reactors as a neutron moderator

7. Group 14 - Carbon Family
Four (4) electrons in valence shell
Contains elements important to life and computers.
Carbon is the basis for an entire branch of chemistry called organic chemistry
Silicon and Germanium
important semiconductors

8. Group 15 - Nitrogen Family Five (5) electrons in the valence shell
Nitrogen makes up over ¾ of the atmosphere
Nitrogen and phosphorus are both important in living things
Most of the world’s nitrogen is not available to living things
Legumes (beans and peanuts) contain nitrogen fixing bacteria so that it is available to plants
Two thirds of the earth’s population dependent on nitrogen fixing bacteria for their food

9. Groups 16 - Oxygen Family or Chalcogens
Six (6) electrons in the valence shell
Oxygen
Molecular oxgyen (O2 ) is necessary for respiration
Ozone (O3 ) protects us from UV radiation
Many things that stink, contain sulfur
Ex: rotten eggs, garlic, skunks, etc.

10. Allotropes
Elements with
different physical properties
But same chemical composition
Examples
Carbon – two forms
Oxygen – two forms
molecular oxygen and ozone

11. Group 17 - Halogens 7 electrons in valence
Very reactive, volatile, diatomic molecule
Always found combined with other elements in nature, like salts
Used as disinfectants and to strengthen teeth
Flouride in water, toothpaste
Chlorine bleach, tabs for pool
Iodine in antiseptics

12. Group 18 - The Noble Gases
A full set of 8 electrons in the valence shell
VERY unreactive, monatomic (only atom per molecule) molecular gases
Helium – balloons and blimps
Neon – the glowing signs we all love
Argon – incandescent bulbs