Bell Work Using your textbook, define the following terms: Metalloid Semiconductor Allotrope

Section 3 Mixed Groups

Objectives Distinguish among metals, nonmetals, and metalloids Describe the nature of allotropes Describe how the properties of metalloids define them as semiconductors

Properties of Metalloids Form ionic and covalent bonds with other elements Have metallic and nonmetallic properties Semiconductor: def. element that conduct electric current under certain conditions Mixed groups- 13,14,15,16,17  contain a combo of metals, nonmetals, and metalloids

Boron Group All have 3 electrons in outer shell BORON, B - metalloid Borax  used in some laundry products to soften water Boric acid  mild disinfectant Boranes  used in jet and rocket fuel

Boron Group conti. ALUMINUM, Al – metal most abundant metal in Earth’s crust strong, lightweight used in cooking pans, siding, airplanes

Carbon Group 4 electrons in outer shell Allotropes- def. different forms of the same element; different molecular structure Carbon, C – nonmetal found in all organic compounds CO 2 natural gas coal & oil

Use Phone… Soft lead metal was once used for writing black marks on paper. Graphite mixed with clay is less toxic and has replaced lead in pencils for writing. The term graphite comes from the Greek word ____________ which means ___________________. Graphein To write

Allotropes in Carbon Diamond- clear, extremely hard each C is bound to 4 C atoms forming tetrahedrons Graphite- black powder consisting of hexagonal layers of C atoms where each C is bound to 3 C Buckminsterfullerene- soccer ball shape used to make tiny tubes  nanotubes

Carbon group conti. Silicon, Si - metalloid 2 nd most abundant element in earth’s crust most found in sand, rocks, and soil 2 allotropes: 1.hard, gray substance 2.brown powder Used in electronic devices ex: computer chips Germanium, Ge – metalloid Semiconductor used in cell phone and other electronics

Tin, Sn- metal Coats other metals to prevent corrosion combines w/ other metals to produce bronze Lead, Pb- metal once used in paint and pencils  TOXIC

Nitrogen Group 5 electrons in the outer shell Tend to share electrons and form covalent compounds w/ other elements Nitrogen, N – nonmetal 4 th most common element in body Used to produce nitrates (NO 3 - ) and ammonia found in fertilizers Phosphorus, P- nonmetal 3 allotropes water softener, fertilizers, match heads, fine china

Nitrogen Group conti. Antimony, Sb (metalloid)& Bismuth, Bi (metal)- used to lower melting point in other metals Bismuth used in automatic fire-sprinkler heads

Oxygen Group 6 electrons in outer shell Oxygen, O - nonmetal 21% air, diatomic molecule O 2 (needed for respiration) electrical storm O 2  ozone molecules O 3 (protection from Sun’s radiation)

Oxygen Group cont. Sulfur, S – nonmetal several allotropes: different shaped crystals & noncrystalline forms Bad smell- rotten eggs! pigments in paint Sulfuric acid  fertilizers Selenium, Se – nonmetal need trace amounts in diet for making antioxidant enzymes Tellurium, Te – metalloid brittle, mildly toxic, rare, silver-white; alloy, no biological function Polonium, Po – metalloid Rare radioactive element

HOMEWORK Chapter Review Worksheet

Synthetic Elements By smashing existing elements with particle accelerated in a heavy ion accelerator, nuclear scientists have been creating elements typically not found on Earth. Except for Technetium 43 and Promethium 61, each synthetic elements has more than 92 protons (transuranium elements). Neptunium- > bombarding U w/ neutrons; ½ disintegrate in 2 days to form plutonium (highly toxic/used in bombs) Pu- > changed to Americium (used in smoke detectors)

Transuranium Elements Unstable Synthetic Many disintegrate quickly Towards the bottom of the periodic table More than 92 protons

Why make elements? Medical applications Weapons applications By studying how these elements form and disintegrate, gain understanding of forces holding the nucleus together. When atoms disintegrate = radioactive Scientists are seeking stability in synthetic elements