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Chapter 19

Chapter 19. Elements and their Properties. 19-1: Metals. 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

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Chapter 19

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  1. Chapter 19 Elements and their Properties

  2. 19-1: Metals • 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

  3. 19-1: Metals • 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.

  4. 19-1: Metals • 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

  5. 19-1: Metals • 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

  6. 19-1: Metals • 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

  7. 19-1: Metals • 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

  8. 19-1: Metals • 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

  9. 19-1: Metals • 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.

  10. 19-1: Metals • 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.

  11. 19-2: Nonmetals • 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

  12. 19-2: Nonmetals • 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.

  13. 19-2: Nonmetals • 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. • H2, O2, N2, Cl2, Br2, I2, F2

  14. 19-2: Nonmetals • 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.

  15. 19-2: Nonmetals • 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.

  16. 19-2: Nonmetals • 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.

  17. 19-3: Mixed Groups • 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.

  18. 19-3: Mixed Groups • 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

  19. 19-3 : Mixed Groups • 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.

  20. 19-3: Mixed Groups • 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.

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