Section 1: Metals

• Properties of Metals

  • In the periodic table, metals are elements found to the left of the stair-step line.

  • Metals: usually have common properties—they are good conductors of heat and electricity, and all but one are solid at room temperature.

    • Mercury is the only metal that is not a solid at room temperature.

  • Metals also reflect light. This is a property called luster.

  • Malleable: can be hammered or rolled into sheets

  • Ductile: can be drawn into wires

  • The atoms of metals generally have one to three electrons in their outer energy levels.

  • In chemical reactions, metals tend to give up electrons easily because of the strength of charge of the protons in the nucleus.

  • Both metals and nonmetals become more chemically stable when they form ions.

  • Metallic Bonding: positively charged metallic ions are surrounded by a cloud of electrons.

  • Outer-level electrons are not held tightly to the nucleus of an atom.

  • The idea of metallic bonding explains many of the properties of metals.

  • Metals are also good conductors of electricity because the outer-level electrons are weakly held.

• The Alkali Metals

  • The elements in Group 1 of the periodic table are the alkali metals.

  • Like other metals, Group 1 metals are shiny, malleable, and ductile. They are also good conductors of heat and electricity.

  • Each atom of an alkali metal has one electron in its outer energy level.

  • Alkali metals and their compounds have many uses.

  • Radioactive Element: one in which the nucleus breaks down and gives off particles and energy.

• The Alkaline Earth Metals

  • The alkaline earth metals make up Group 2 of the periodic table.

  • Like most metals, these metals are shiny, malleable, and ductile. They are also similar to alkali metals in that they combine so readily with other elements that they are not found as free elements in nature.

  • Magnesium metal is one of the metals used to produce the brilliant white color in fireworks.

  • Most life on Earth depends upon chlorophyll, a magnesium compound that enables plants to make food.

  • Calcium is seldom used as a free metal, but its compounds are needed for life.

  • Radium, the last element in Group 2, is radioactive and is found associated with uranium.

• Transition Elements: elements in Groups 3 through 12 in the periodic table.

  • They are called transition elements because they are considered to be elements in transition between Groups 1 and 2 and Groups 13 through 18.

  • Transition elements often form colored compounds.

  • The first elements in Groups 8, 9, and 10—iron, cobalt, and nickel—form a unique cluster of transition elements.

  • Iron—the main component of steel—is the most widely used of all metals.

  • Most coins now are made of nickel and copper.

  • Copper often is used in electrical wiring because of its superior ability to conduct electricity and its relatively low cost.

  • Zinc, cadmium, and mercury are found in Group 12 of the periodic table.

    • Zinc and cadmium often are used to coat, or plate, other metals such as iron because of this protective quality.

  • Mercury is a silvery, liquid metal—the only metal that is a liquid at room temperature.

  • Mercury is poisonous and can accumulate in the body.

• The Inner Transition Metals

  • The two rows of elements that seem to be disconnected from the rest on the periodic table are called the inner transition elements.

  • Lanthanum, cerium, praseodymium, and samarium are used with carbon to make a compound that is used extensively by the motion picture industry.

  • The first row includes a series of elements with atomic numbers of 58 to 71.

  • The second row of inner transition metals includes elements with atomic numbers ranging from 90 to 103.

  • These elements are called the actinide series because they follow the element actinium.

  • Thorium and uranium are the actinides found in the Earth’s crust in usable quantities.

  • Uranium is best known for its use in nuclear reactors and in weapons applications, but one of its compounds has been used as photographic toner, as well.

• Metals in the Crust

  • Earth’s hardened outer layer, called the crust, contains many compounds and a few uncombined metals such as gold and copper.

  • Chromium is important because it is used to harden steel, to manufacture stainless steel, and to form other alloys.

  • Metals in Earth’s crust that combined with other elements are found as ores.

    • Most ores consist of a metal compound, or mineral, within a mixture of clay or rock.

  • If the cost of removing the waste rock becomes greater than the value of the desired material, the mineral no longer is classified as an ore.

Section 2: Nonmetals

• Properties of Nonmetals

  • Most of your body’s mass is made of oxygen, carbon, hydrogen, and nitrogen.

  • Nonmetals: elements that usually are gases or brittle solids at room temperature.

  • Because solid nonmetals are brittle or powdery, they are not malleable or ductile.

  • Most nonmetals do not conduct heat or electricity well, and generally they are not shiny.

  • In the periodic table, all nonmetals except hydrogen are found at the right of the stair-step line.

  • As a group, nonmetals are poor conductors of heat and electricity.

  • When nonmetals gain electrons from metals, the nonmetals become negative ions in ionic compounds.

  • When bonded with other nonmetals, atoms of nonmetals usually share electrons to form covalent compounds.

• Hydrogen

  • Most hydrogen on Earth is found in the compound water.

  • When water is broken down into its elements, hydrogen becomes a gas made up of diatomic molecules.

  • Diatomic Molecule: consists of two atoms of the same element in a covalent bond.

  • Hydrogen is highly reactive.

  • Hydrogen can gain an electron when it combines with alkali and alkaline earth metals.

• The Halogens

  • Halogen lights contain small amounts of bromine or iodine.

    • These elements, as well as fluorine, chlorine, and astatine, are called halogens and are in Group 17.

  • Salt: an ionic compound.

  • In the gaseous state, the halogens form reactive diatomic covalent molecules and can be identified by their distinctive colors.

  • Fluorine is the most chemically active of all elements.

  • Chlorine compounds are used to disinfect water.

  • Bromine, the only nonmetal that is a liquid at room temperature, also is extracted from compounds in seawater.

  • Iodine, a shiny purple-gray solid at room temperature, is obtained from seawater. When heated, iodine changes directly to a purple vapor.

  • Sublimation: The process of a solid changing directly to a vapor without forming a liquid

  • Astatine is the last member of Group 17. It is radioactive and rare, but has many properties similar to those of the other halogens.

• The Noble Gases

  • The noble gases exist as isolated atoms.

  • No naturally occurring noble gas compounds are known, but several compounds of xenon and krypton with fluorine have been created in a laboratory.

  • The stability of noble gases is what makes them useful.

Section 3: Mixed Groups

• Properties of Metalloids

  • Metalloids share unusual characteristics.

  • Metalloids: an form ionic and covalent bonds with other elements and can have metallic and nonmetallic properties.

  • Some metalloids can conduct electricity better than most nonmetals, but not as well as some metals, giving them the name semiconductor.

  • The mixed groups—13, 14, 15, 16, and 17—contain metals, nonmetals, and metalloids.

• The Boron Group

  • Boron, a metalloid, is the first element in Group 13.

  • Aluminum, a metal in Group 13, is the most

    abundant metal in Earth’s crust.

    • Aluminum is used frequently in the construction of air- planes because it is light and strong.

• The Carbon Group

  • Each element in Group 14, the carbon family, has four electrons in its outer energy level, but this is where much of the similarity ends.

  • Carbon occurs as an element in coal and as a compound in oil, natural gas, and foods.

  • All organic compounds contain carbon, but not all carbon compounds are organic.

  • Silicon is second only to oxygen in abundance in Earth’s crust.

    • Silicon occurs as two allotropes.

  • Allotropes: different forms of the same element, have different molecular structures.

  • Semiconductors: elements that conduct an electric current under certain conditions.

  • Germanium, the other metalloid in the carbon group, is used along with silicon in making semiconductors.

  • Diamond, graphite, and buckminsterfullerene are allotropes of an element.

  • In a diamond, each carbon atom is bonded to four other carbon atoms at the vertices, or corner points, of a tetrahedron.

    • A diamond is clear and extremely hard.

  • Graphite is a black powder that consists of hexagonal layers of carbon atoms.

    • The fourth electron of each atom is bonded weakly to the layer next to it.

• The Nitrogen Group

  • The nitrogen family makes up Group 15.

  • Nitrogen is the fourth most abundant element in your body.

  • Phosphorus is a nonmetal that has three allotropes.

  • Antimony is a metalloid, and bismuth is a metal.

• The Oxygen Group

  • Group 16 on the periodic table is the oxygen group.

  • Oxygen, a nonmetal, exists in the air as diatomic molecules, O2.

  • Nearly all living things on Earth need O2 for respiration.

  • Sulfur is a nonmetal that exists in several allotropic forms.

  • Sulfur combines with metals to form sulfides of such distinctive colors that they are used as pigments in paints.

  • The nonmetal selenium and two metalloids—tellurium and polonium—are the other Group 16 elements.

• Synthetic Elements

  • By smashing existing elements with particles accelerated in a heavy ion accelerator, scientists have been successful in creating elements not typically found on Earth.

  • Bombarding uranium with neutrons can make neptunium, element 93.

  • Transuranium Elements: Elements having more than 92 protons, the atomic number of uranium

    • All of the transuranium elements are synthetic and unstable, and many of them disintegrate quickly.

  • Radioactive elements can be useful.