Chapter 19

1. Chapter 19 Elements and Their Properties

2. 19.1 Metals

3. Properties of Metals • Metals have common properties • Good conductors of heat and electricity • All but Mercury are solid at room temperature • Reflect light – Luster • Easily hammered/rolled into sheets – Malleable • Easily drawn into wires - Ductile

4. Ionic Bonding • Metal atoms have usually 1-3 valence electrons • Tend to give their electrons up easily • When they combine with nonmetals, they lose electrons to the nonmetals, forming ionic bonds • This makes them more chemically stable

5. Metallic Bonding • Occurs among metal atoms • Positive charged metallic ions are surrounded by a cloud of electrons • The electrons move freely among many different positively charged metal ions • Explains many properties of metals • Hammered • Good conductors

6. Alkali Metals • Group one • Properties • Shiny • Malleable • Ductile • Softer • Most reactive of all the metals – react rapidly/violently w/ oxygen and water • Don’t occur in elemental form in nature – stored in oil

7. Alkali Metals • One electron in its outer energy level • The atom gives up this electron with it combines with another atom ex. NaCl • Living things need alkali metals/their compounds • K, Na, Li Radioactive Element – one in which the nucleus breaks down and gives off particles and energy ex. Francium – very rare & radioactive

8. Alkaline Earth Metals • Group 2 • Also not found as free elements in nature – combine so readily with other elements • 2 electrons in outer energy level • These are given up with they combine with nonmetals and becomes a positively charged ion in a compound such as CaF2

9. Alkaline Earth Metals • Magnesium & Strontium – used in fireworks • Chlorophyll – Magnesium compound – enables plants to make food • Magnesium’s lightness & strength • Cars, planes, spacecraft • Household ladders, baseball/softball bats

10. Alkaline Earth Metals • Calcium compounds needed for life • Calcium phosphate – makes bones strong • Barium compound – swallowed to take x-rays to diagnose internal abnormalities • Radium once used to treat cancer • They now use other readily available radioactive elements

11. Transition Elements • Elements in Groups 3-12 • Often occur in nature as uncombined elements b/c they are more stable • Often form colored compounds

12. Iron, Cobalt, Nickel • Called the Iron Triad • Used to create steel/other metal mixtures • Nickel – added to some metals to make them stronger or give them a shiny protective coating • Iron – main component of Steel – most widely used of all metals • Second most abundant metallic element in Earth’s crust (Al is 1st)

13. Copper, Silver, Gold • Very stable and malleable • Found as free elements in nature • Copper often used in electrical wiring • Silver compounds – photographs, film • Silver & Gold – used in jewelry • Once used to make coins – termed the coinage metals • Not anymore b/c $$$, most coins now are Ni and Cu

14. Zinc, Cadmium, Mercury • Zn, Cd often used to coat other metals • Cd used in rechargeable batteries • Hg – silvery, liquid metal • Used in thermometers, thermostats, switches, batteries • Poisonous – can accumulate in body

15. Inner Transition Metals • Lanthanides – follow the element lanthanum • Used with carbon to make compound used to make movies • Used to produce color in TV screens

16. Inner Transition Metals • Actinides – second row • Follow the element actinium • All radioactive and unstable • Used to make high quality camera lenses, nuclear reactors, weapons

17. Questions • How is metallic bonding different from covalent bonding (when two elements share electrons) • How would you test something to see if it is a metal? • Why is mercury rarely used in thermometers that take body temperature? • Explain why copper is a good choice for use in electrical wiring. What type of elements would not work well for this purpose?

18. 19.2 Nonmetals

19. Properties of Nonmetals • Nonmetals – elements that are usually gasses or brittle solids at room temperature • Not malleable or ductile • Most don’t conduct well • Generally not shiny • All nonmetals except hydrogen are found to the right of the stair step line

20. Bonding in Nonmetals • Electrons in most nonmetals are attracted to the nucleus of the atom, so they are poor conductors • Can form ionic or covalent bonds • When nonmetals get electrons from metals, they become the NEGATIVE ions in ionic compounds • When bonding w/ other nonmetals, usually share electrons to form covalent compounds

21. Hydrogen • 90% of atoms in the universe are hydrogen • Most on earth found in water When water is broken down, H becomes a gas made up of diatomic molecules Diatomic molecule – 2 atoms of the same element in a covalent bond

22. Hydrogen • Highly reactive • Single electron – shared when combined with other nonmetals • Hydrogen can gain an electron when combining with alkali and alkaline earth metals to form a hydride ex. NaH (sodium hydride)

23. Halogens • Group 17 • Very reactive in elemental form • Compounds have many uses • Fluorides – toothpaste, city water, water to disinfect • 7 electrons in outer energy level, so only need 1 to be HAPPY ☺

24. Halogens • If a halogen gains an electron from a metal, forms an ionic compound called a Salt ex. NaCl • In gas state, halogens form reactive diatomic covalent molecules – can be identified by colors • Chlorine – greenish yellow • Bromine – reddish orange • Iodine - violet

25. Halogens • Fluorine – most chemically active of all elements • Uses of Halogens • Chlorine compounds – distinct small, most abundant halogen, used in bleaches to whiten things • Bromine – only liquid nonmetal at room temp., used in dyes in cosmetics • Iodine – shiny solid at room temp, when heated changes directly to purple vapor – sublimination • Essential to diet to produce certain hormones

26. Noble Gases • Stable • Outermost energy levels full Neon and Argon - neon lights Lightweight helium used in balloons Argon and Krypton used in electric light bulbs to produce light in lasers