Elements & Their Properties Chapter 17

 Properties of Metals  Conduct heat & electricity  Luster: reflects light well  Malleable: can be hammered or rolled into sheets  Ductile: can be drawn into wires

 Properties of Metals  Ionic bonding: combine with nonmetals by losing electrons  Metallic bonding:  positively charged metallic ions are surrounded by a cloud of electrons;  ions are in sliding layers & electrons are weakly held;  readily form ionic bonds with nonmetals

Group1 except Hydrogen  The Alkali Metals  Softer & more reactive than other metals  Highly reactive with oxygen & water  Don’t occur naturally as elemental forms  Combine readily with other elements due to a single electron in the outer energy level

Group1 except Hydrogen  The Alkali Metals  Multiple uses  Human health: sodium, potassium & lithium compounds  Photocells: some depend on rubidium or cesium  Francium: a radioactive element which breaks down, giving off particles and energy

Group 2  The Alkaline Earth Metals  Not found naturally in elemental form;  two electrons in the outer energy layer  Applications:  Strontium and magnesium found in fireworks  Magnesium in vehicles, ladders and bats  Calcium in statues and countertops  Human body:  Calcium in bones  Barium in disease diagnoses  Radium formerly used in cancer treatment

Groups 3-12  Transition Elements  Often occur in nature as uncombined elements  Form colored compounds  Chromium found in rubies & emeralds  Iron triad: iron, cobalt, nickel  Iron: most widely used metal & main ingredient in steel; abundant in earth’s crust  Cobalt & nickel: used in some steels  Nickel: used to coat other metals

Groups 3-12  Transition Elements  Copper, silver, gold  Coinage metals (used to make coins)  Copper: used in electric wiring because it is a superior conductor of electricity  Silver: used in photographic film & paper; jewelry  Gold: used in jewelry

Groups 3-12  The Transition Elements  Zinc, cadmium, mercury  Group 12 on the periodic table  Zinc & cadmium: used to coat other metals  Mercury: only room temperature liquid metal; used in thermometers and batteries

 The Inner Transition Metals  Seen disconnected from the rest of the table  Lanthanides: includes lanthanum, cerium, praseodymium, amarium, europium, gadolinium, and terbium  Actinides: all are radioactive and unstable; uranium is the best known

 Properties of Nonmetals  Usually gases or brittle solids at room temperature  Not malleable or ductile  Poor conductors  Not lustrous  Make up most of the human body

 Properties of Nonmetals  Ionic compounds: form when nonmetals gain electrons from metals and become negative ions (ex: sodium chloride)  Covalent compounds: form when nonmetals share electrons with other nonmetals (ex: ammonia)

 Hydrogen  The most common element in the universe  Mainly found as a diatomic molecule: two atoms of the same element in a covalent bond  Highly reactive element found mostly on earth as part of a water compound

 The Halogens  Bromine, iodine, flourine, chlorine, astatine  A salt forms when a halogen gains one electron from a metal  Use of halogens  Chlorine: disinfectant and bleach  Bromine: dyes in cosmetics  Iodine: hormone regulation

 The Halogens  Sublimation  A solid changes directly into a gas without first becoming a liquid  Iodine sublimates when heated

 The Noble Gases  Stable because their outer energy level is full; they do not react with other elements.  Helium: used in blimps and balloons  Neon, argon, and krypton: used in lights  Neon, argon – neon lights  Argon, krypton – electric lights and lasers

 The Properties of Metalloids  Form ionic & covalent bonds  Have some metallic & some non-metallic properties  Partial conduction gives them semiconductor characteristics

 The Boron Group  Named for the first element in Group 13  Boron: used in water softening products, antiseptics, and fuels  Aluminum: abundant in earth’s crust; used in cans, foil, pans, building materials, and aircraft

 The Carbon Group  4 electrons in the outer energy level  Carbon: found in coal, oil, natural gas, and food  Produces carbon dioxide when combined with oxygen  Silicon: found in sand, rocks, soil  Occurs as an allotrope (same element with different structure)  Main component in semiconductors, which conduct electricity under certain conditions

 The Carbon Group  Germanium: also used in semiconductors  Tin: used to coat other metals  Lead: toxic, so no longer used in paints  Diamonds and graphite are allotropes of carbon

 The Nitrogen Group  5 electrons in the valence shell  Tend to form covalent bonds  Nitrogen: used to make nitrates & ammonia  Phosphorous: used in water softeners, fertilizers, match heads, fine china  Antimony & bismuth: used with other metals to lower their melting points

 The Oxygen Group  Group 16  Oxygen: makes up 20% of air, used by living things in respiration, provides protection from the sun’s radiation in the form of ozone  Sulfur: used to form sulfides in paint pigment  Selenium: used in photocopiers & multivitamins  Tellurium & polonium: also oxygen elements

 Synthetic Elements  Synthetic means “man-made”  Scientists create elements not usually found on earth  They usually disintegrate quickly

 Synthetic Elements  Uranium can be made into neptunium which forms plutonium when it disintigrates  Plutonium can be changed into americium, which is used in smoke detectors

 Synthetic Elements  Transuranium elements have more than 92 protons and are synthetic & unstable  Studying these elements help scientists understand the forces holding the nucleus together  Element 114 lasted 30 seconds  It combined 114 protons with 175 neutrons  It broke apart due to the enormous repulsion between the protons