Physical Science Ch. 20

Section 1 Metals

Properties of metals Conduct heat and electricity Luster Malleable reflect light well Malleable can be hammered or rolled into sheets Ductile can be drawn into wires Electron Donors combine with nonmetals by losing electrons

Metallic Bonding Positively charged metallic ions are surrounded by a cloud of electrons Ions are in sliding layers and electrons are weakly held Readily form ionic bonds with nonmetals

The Alkali Metals softer and more reactive than other metals Highly reactive w/ oxygen & water don’t occur naturally as elemental forms Combine readily with other elements due to single electron in outer energy level Located in 1st column of periodic table

Uses of Alkali Metals Human health Photocells Francium sodium, potassium, and lithium compounds Photocells some depend on rubidium or cesium Francium a radioactive element which breaks down giving off particles and energy

The Alkaline Earth Metals not found naturally in elemental form two electrons in outer energy level Located in the 2nd column of the periodic table

Alkaline Earth Metals The Applications Uses with the Human body strontium and magnesium found in fireworks magnesium in vehicles, ladders, and bats calcium in statues and countertops Uses with the Human body calcium in bones barium in disease diagnoses radium formerly used in cancer treatments

Transition Elements They often occur in nature as uncombined elements Located in the sunken in area of the periodic table The number of valence electrons have a tendency to vary (transition) at times

Transition Elements Typically form colored compounds chromium is in rubies & emeralds Iron triad (iron, cobalt, and nickel) Iron most widely used of all metals main ingredient in steel abundant in Earth’s crust Cobalt and nickel used in some steels Nickel used to coat other metals

Copper, silver, gold Copper Silver Gold Zinc and cadmium Mercury coinage metals since once were commonly used in coins Copper used in electric wiring because it is a superior electricity conductor Silver used in photographic film and paper; jewelry Gold used in jewelry Zinc and cadmium often used to coat or plate other metals Mercury only room temperature liquid metal used in thermometers and batteries

Inner Transition Metals Rare earth elements seem disconnected from the rest of periodic table The Lanthanides Series (1st row) The Actinides (2nd row) All are radioactive and unstable Uranium is the best known

Section 2 Nonmetals

Nonmetals Properties of nonmetals Gases or brittle solids at room temperature Not malleable Not ductile Poor conductors of heat and electricity Lustrous Electron acceptos

Compounds formed by Nonmetals Ionic compounds form when nonmetals gain electrons from metals and become negative ions Covalent compounds form when nonmetals share electrons with other nonmetals

Sublimation Diatomic molecule a solid changes directly into a gas without first becoming a liquid Diatomic molecule two atoms of the same element in covalent bond

Magnificent Seven Bromine Oxygen Fluoride Iodine Nitrogen Chlorine 7 diatomic elements Always occur with 2 atoms Bromine Oxygen Fluoride Iodine Nitrogen Chlorine Hydrogen

More about nonmetals Hydrogen most common element in universe diatomic molecule Highly reactive element found mostly on Earth as part of water compound

More about nonmetals The Halogens (7th column) Use of halogens 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

Noble Gases Exist as isolated, stable atoms Located in 8th column Have complete outer energy level filled Helium used in blimps and balloons Neon, argon, and krypton used in lights

Section 3 Mixed Groups

Properties of metalloids Located around the stair steps Form ionic & covalent bonds Have some metallic & some non-metallic properties Partial conduction gives them semiconductor characteristics

Boron Group Named for the first element in 3rd column Has 3 valence electrons Boron used in water softening products, antiseptics, and fuels Aluminum abundant in Earth’s crust used in cans, foil wrap, pans, building materials, and aircraft

Carbon Group Named for first element in 4th column Four valence electrons Carbon found in coal, oil, natural gas, and foods Silicon Occurs as an allotrope same element with different molecular structures Found in sand, rocks, and soil The main component in semiconductors conduct electricity under certain conditions

Carbon Group con’t Germanium Tin Lead Allotropes of carbon also used in semiconductors Tin used to coat other metals Lead toxic, so no longer used in paint Allotropes of carbon Diamonds Graphite Buckminsterfullerene

Nitrogen Group Named for first element in 5th column Has five valence electrons tends to form covalent bonds Nitrogen used to make nitrates and ammonia Phosphorus used in water softeners, fertilizers, match heads, fine china Antimony and bismuth used with other metals to lower their melting points

Oxygen Group Named for first element in 6th column Has six valence electrons Oxygen makes up 20% of air is used by living things in respiration provides protection from Sun’s radiation Sulfur used to form sulfides for pigment in paint Selenium used in photocopiers and multivitamins

Synthetic Elements (man made) Created elements not usually found on Earth synthetic elements usually disintegrate quickly. Uranium can be made into neptunium which forms plutonium when it disintegrates. Plutonium can be changed into americiun used in smoke detectors. Transuranium elements have more than 92 protons are synthetic and unstable

The study of synthesized elements helps scientists to understand the forces holding the nucleus together. Element 114 lasted for 30 seconds. It combined 114 protons with 175 neutrons. It broke apart due to enormous repulsion between the protons.