1. REPRESENTATIVE ELEMENTS
Section 2
REPRESENTATIVE ELEMENTS

2. What we’ll learn? Recognize the properties of representative elements.
Identify uses for the representative elements.
Classify elements into groups based on similar properties.

3. Why it’s important?
Many representative elements play key roles in your body, your environment, and in the things you use everyday…

4. Vocabulary: Alkali metal Alkaline earth metal Semiconductor Halogen
Noble gas

5. Groups 1 & 2 Always found in combined w/ other elements. Active metals
All metals except Hydrogen

6. Hydrogen Hydrogen belongs to a family of its own.
Hydrogen is a diatomic, reactive gas.
Hydrogen was involved in the explosion of the Hindenberg.
Hydrogen is promising as an alternative fuel source for automobiles

7. Alkali Metals Silvery solids Low densities Low melting points Example:
Lithium (Li)- batteries in cameras
(sodium chloride)-table salt
Sodium (Na)- potatoes
Potassium (K)- bananas

8. Alkaline Earth Metals Group 2 elements -denser, harder
Low melting point
Reactive
Example:
Beryllium (Be) –gems, emerald
Magnesium (Mg)- chlorophyll in plants

9. Groups 13 through 18 Metals, non metals, metalloids
Solid, liquid and gas

10. Group 13 (Boron Family)
Metals except Boron (B) brittle, black metalloid
used in cookware
Aluminum (Al) soft drink cans
baseball bat, cookware
Gallium (Ga) solid metal, low melting point
computer chips

11. Group 14 (Carbon Family) Carbon (C) – non metal
- exist as diamond & graphite
- found in living things
Silicon (Si) metalloid, found in sand (glass)
computer chips
Germanium (Ge) metalloid
used in electronics as semi conductor

12. Tin (Sn) toothpaste
coating on steel cans for food
Lead (Pb) apron (dental x-rays)
car batteries
x-ray equipment

13. Group 15 (Nitrogen Family)
Nitrogen (N) – air you breath
- non metal
Ammonia gas – cleanser, disinfectant, solid fertilizers, nylon for parachutes.
Phosphorus (P)-
Red (less active)- matches
White (more active) – can’t be exposed to O2
- Found in healthy teeth & bones
-Fertilizers

14. Group 16 (Oxygen Family) Oxygen (O) –earth’s atmosphere
- earth’s rocks & minerals
- ozone
- foam (fire fighters)
Sulfur (S) – solid, yellow non metal
- sulfuric acid ( chemical) used as paints, fertilizers, detergents, synthetic fibers, rubber.

15. Selenium (Se)- conducts electricity (solar cells)
- Light meters, photographic materials
- photocopy machines

16. Group 17 (Halogens) All non metals except astatine (metalloid)
Salt formers (halogens) w/ alkali metals
Chlorine (Cl)- w/ sodium (table salt)
- kill bacteria (pool)
Flourine ( Fl)- most reactive
Iodine (I)- least reactive
- needed by many systems in our body.

17. Group 18 (The Noble Gases)
* Rarely combine with Other elements. Helium (He)- yellow, less dense - balloons Neon (Ne) – advertising signs - red orange Argon (Ar) – bluish violet - most abundant

18. Krypton (Kr)- combined with neon lights used in light bulbs.
- landing strips at airport runways
Xenon (Xe)- strobe lights
- photographic flash tubes.
Radon (Rn) – radioactive gas
- can cause lung cancer