Presentation on theme: "Elements and their Properties. Metals (on the left of the stair-step line) Usually have common properties Good conductors of heat and electricity."— Presentation transcript:
Elements and their Properties
Metals (on the left of the stair-step line) Usually have common properties Good conductors of heat and electricity Have luster = reflect light Are malleable = can be hammered or rolled into sheets Are ductile = drawn into wires All, but one, are solid at room temperature
Ion = charged particle that has either more or fewer electrons than protons The atoms of metals typically have one to three electrons in their outer energy levels. Metals tend to give up their electrons because of the strength of charge of the protons in the nucleus. When metals combine with nonmetals, the atoms of the metals tend to lose electrons to the atoms of the nonmetals – thus forming ionic bonds.
Metallic bonding = when positively charged metallic ions are surrounded by a cloud of electrons Because of this, the electrons move freely among the many positively charged ions. This type of bonding explains many properties of metals: Malleability/ductility – metals do not break instead the ions slide past each other Good conductor of electricity – outer-level electrons are weakly held
Alkali metals (Group 1) Shiny, malleable, and ductile Good conductors of heat and electricity Are softer than most metals Are the most reactive They react rapidly, sometime violently, with oxygen and water Since they combine readily with other elements, they don’t occur in nature in their elemental form Are stored in substances that are unreactive, such as oil Have one electron in its outer energy level that is given up, resulting in a +1 ion
Alkaline Earth metals (Group 2) Shiny, malleable, and ductile Combine readily with other elements, so they are not found as free elements in nature Has two electrons in its outer energy level that are given up, resulting in a +2 ion
Transition elements (Group 3-12) Are called transition elements because they are the elements in transition between groups 1 and 2 and groups 13 through 18 Are the most familiar since they occur in nature as uncombined elements Often form colored compounds
Iron triad (found in Groups 8, 9, and 10) Iron, cobalt, and nickel Used in the process to make steel Coinage metals (found in Group 11) Copper, silver, and gold Were used in coins, but are not anymore since they are so expensive Copper is often used in electrical wiring because of its superior ability to conduct electricity Used in jewelry because of their attractive color, relative softness, resistance to corrosion, and rarity
Zinc, cadmium, and mercury Found in Group 12 Zinc and cadmium are used to coat, or plate, other metals Cadmium is used in rechargeable batteries Mercury, being a liquid, is used in thermometers, thermostats, switches, and batteries It is poisonous and can accumulate in the body. People have died after eating fish that lived in mercury- contaminated water.
Inner Transition metals They fit in the periodic table between Groups 3 and 4 in periods 6 and 7. To save room, they are listed below the table. Known as the Lanthanides and Actinides Read “Metals in the Crust” on page 577 on your own.
Nonmetals Usually are gases at room temperature Not malleable or ductile Most do not conduct heat or electricity well Generally they are not shiny (lack luster) All nonmetals except for hydrogen are right of the stair-step line
Most nonmetals can form ionic and covalent compounds. 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 About 90% of all the atoms in the universe are hydrogen. Most is found in the form of water. It is derived from the Greek word for “water forming.” It is highly reactive. Diatomic molecule = consists of two atoms of the same element in a covalent bond. H 2, O 2, N 2, Cl 2, Br 2, I 2, F 2
The Halogens (Group 17) Are very reactive in their elemental form. Fluorine is the most chemically active of all elements. Can be identified by their distinctive colors. Cl = greenish-yellow; Br = brownish-orange; and I = violet Have seven electrons in their outer energy level, so only one electron is needed to complete the energy level. If it gets the electron from a metal, an ionic compound, or salt, is formed. In the gas state, halogens form reactive diatomic covalent molecules.
Halogens have many uses: Fluorides are added to toothpaste and to city water systems to prevent tooth decay. Chlorine compounds are added to water to disinfect it. Bleach also contains chlorine. Bromine, the only liquid nonmetal, is used in dyes in cosmetics. Iodine undergoes sublimation, or the process of a solid changing directly to a vapor without forming a liquid. It is essential in your diet to produce a hormone and to prevent a goiter.
The Noble Gases Exist as isolated atoms Are stable because their outermost energy levels are full No naturally occurring noble gas compounds are known, but several have been created in a lab. The stability of noble gases makes them useful. Helium is used in blimps and balloons. Neon and argon are used in “neon lights.” Argon and krypton are used in electric light bulbs to produce light in lasers.
Metalloids Can form ionic and covalent bonds with other elements Can have metallic and nonmetallic properties Semi-conductors = the name given to some metalloids that can conduct electricity better than most nonmetals, but not as well as some metals. With the exception of aluminum, the metalloids are located along the stair-step line.
The Mixed Groups 13, 14, 15, 16, and 17 – contain metals, nonmetals, and metalloids. The Boron Group = Group 13 The Carbon Group = Group 14 The Nitrogen Group = Group 15 The Oxygen Group = Group 16 The Halogens = Group 17
Allotropes = different forms of the same element having different molecular structures. Silicon One is a hard, gray substance. The other is a brown powder. Carbon Diamond – clear and extremely hard Graphite – black powder Buckminsterfullerene – soccer-ball shaped molecule used to synthesize extremely thin, graphitelike tubes.
Transuranium elements Elements that have more than 92 protons. These elements do not belong exclusively to the metal, nonmetal, or metalloid group. All are synthetic and unstable, and many disintegrate quickly.