REPRESENTATIVE ELEMENTS Section 2 REPRESENTATIVE ELEMENTS
What we’ll learn? Recognize the properties of representative elements. Identify uses for the representative elements. Classify elements into groups based on similar properties.
Why it’s important? Many representative elements play key roles in your body, your environment, and in the things you use everyday…
Vocabulary: Alkali metal Alkaline earth metal Semiconductor Halogen Noble gas
Groups 1 & 2 Always found in combined w/ other elements. Active metals All metals except Hydrogen
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
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
Alkaline Earth Metals Group 2 elements -denser, harder Low melting point Reactive Example: Beryllium (Be) –gems, emerald Magnesium (Mg)- chlorophyll in plants
Groups 13 through 18 Metals, non metals, metalloids Solid, liquid and gas
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
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
Tin (Sn) toothpaste coating on steel cans for food Lead (Pb) apron (dental x-rays) car batteries x-ray equipment
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
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.
Selenium (Se)- conducts electricity (solar cells) - Light meters, photographic materials - photocopy machines
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.
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
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