Physical Science Chapter 19

Elements and Their Properties

1

Let’s Review

Explain what your remember about how the periodic table is organized.

Number the Groups and Periods

Where are the metals?

Where are the nonmetals?

Where are the metalloids?

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

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19:1 Metals

A. Properties of metals

1. Conductive- Conduct heat and electricity

2. Luster—reflect light well

3. Malleable— can be hammered

or rolled into sheets.

4. Ductile– can be drawn into wires

5

Read Properties of Metals page 570.

19:1 Metals

5. Ionic bonding—combine with nonmetals by losing electrons

• When metals combine with nonmetals, the atoms of the metals tend to lose electrons to the atoms of nonmetals, forming ionic bonds.

6

Read page 571-Ionic Bonding, Metallic Bonding.

19:1 Metals

6. Metallic bonding —positively charged metallic ions are surrounded by a cloud of electrons; ions are in sliding layers and electrons are held weakly. Readily form ionic bonds with nonmetals.

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B. The Alkali Metals—softer and more reactive than other metals

1. Highly reactive with oxygen and water; don’t occur naturally as elemental forms

2. Combine readily with other elements due to single electron in outer energy level

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3. Multiple uses

a. Human health —sodium, potassium, and lithium compounds

b. Photocells —some depend on rubidium or cesium

c. Francium —a radioactive element which breaks down giving off particles and energy

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Alk

ali M

etal

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19:1

C. The Alkaline Earth Metals—not found naturally in elemental form; two electrons in outer energy level1. Applications— strontium and

magnesium found in fireworks; magnesium in vehicles, ladders and bats; calcium in statues and countertops 11

19:1

2. Human body— calcium in bones; barium in disease diagnoses; radium formerly used in cancer treatment

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Alk

alin

e E

arth

Met

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19:1

D. Transition Elements —often occur uncombined in nature.

1. Typically form colored compounds—chromium found in rubies and emeralds

2. Iron triad— iron, cobalt, and nickel

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19:1

a. Iron —most widely used of all metals and main ingredient in steel; abundant in Earth’s crust

b. Cobalt and nickel—used in some steel

c. Nickel—used to coat other metals

15

Read page 574-5. Transition Elements.

Iron TriadIron Mining 6.37

19:1

3. Copper, silver, gold—coinage metals since once were commonly used in coins

a. Copper—used in electric wiring because it is a superior electricity conductor

b. Silver—used in photographic film and paper; jewelry

c. Gold—used in jewelry17

Read page 574-5—Transition Elements

Co

inag

e M

etal

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19:1

4. Zinc, cadmium, mercury—group 12 on periodic tablea. Zinc and cadmium—

often used to coat or plate other metals

b. Mercury—only room temperature liquid metal; used in thermometers and batteries

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Zin

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E. Inner Transition Metals—seem disconnected from rest of periodic table1. The Lanthanides—include lanthanum,

cerium, praseodymium, samarium, europium, gadolinium and terbium

2. The Actinides—all are radioactive and unstable; uranium is the best known

Read page 576- Inner Transition Elements

• 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.

22Lanthanides and Actinides .57

Metals 6.31

• Most of your body’s mass is made of oxygen, carbon, hydrogen, and nitrogen. Calcium, a metal, and other elements make up the remaining four percent of your body’s mass.

19:2 Nonmetals

A. Properties of nonmetals—usually gases or brittle solids at room temperature; are not malleable or ductile; usually poor conductors of heat and electricity; usually not lustrous.1. Ionic compounds—form when nonmetals

gain electrons from metals and become negative ions

2. Covalent compounds—form when nonmetals share electrons with other nonmetals

24

Read page 578- Properties of Nonmetals

19:2 Nonmetals

B. Hydrogen—most common element in universe1. A diatomic molecule —two atoms of the same

element in covalent bond

2. Highly reactive element found mostly on Earth as part of water compound.

1.

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• Hydrogen can gain an electron when it combines with alkali and alkaline earth metals. These compounds are called hydrides.

Read page 579—Hydrogen

C. The Halogens—include bromine, iodine, fluorine, chlorine and astatine

1. A salt forms when a halogen gains one electron from a metal

2. Uses of halogens

a. Chlorine—disinfectant and bleach

b. Bromine—dyes in cosmetics

c. Iodine—hormone regulation

3. Sublimation—a solid changes directly into a gas without first becoming a liquid

26The Halogens .44

Hal

og

ens

D. Noble Gases—

exist as isolated, stable atoms1. Helium—used in blimps and balloons

2. Neon, argon and krypton—used in lights

3

Noble Gases .59

No

ble

Gas

es

19:3 Mixed Groups

A. Properties of Metalloids—form ionic and covalent bonds; have some metallic and some nonmetallic properties; partial conduction gives them semiconductor characteristics

30

Read page 584—Mixed Groups—Reading Guide-Properties of Mettaloids.

B. The Boron Group—named for the first element in Group 131. Boron—used in

water softening products, antiseptics and fuels

2. Aluminum—abundant in Earth’s crust; used in cans, foil wrap, pans, building materials, and aircraft

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Read page 584-Boron Group

Bo

ron

Gro

up

C. The Carbon Group—four electrons in outer energy level

1. Carbon—found in coal, oil, natural gas, foods.

2. Silicon occurs as an allotrope—same element with different molecular structuresa. Silicon found in sand, rocks, and

soil

b. The main component in semiconductors, which conduct electricity under certain conditions.

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Read page 585-Carbon Group

Carbon Group 1.33

Car

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19:3 Mixed Groups

c. Germanium—also used in semiconductors

d. Tin—used to coat other metals

e. Lead— toxic, so no longer used in paint

f. Diamonds, graphite and buckminsterfullerene are all allotropes of carbon

35

D. The Nitrogen Group—five electrons in outer energy level; tend to form covalent bonds

1. Nitrogen—used to make nitrates and ammonia

2. Phosphorus—used in water softeners, fertilizers, match heads, fire china

3. Antimony and bismuth—used with other metals to lower their melting points

36Nitrogen Group 1.22

Nit

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Circle Graphs

Let’s look at Circle Graphs on page 587.

E. The Oxygen Group—Group 16

1. Oxygen—makes up 20% of air, used by living things in respiration, and provides protection for Sun’s radiation

2. Sulfur—used to form sulfides for pigment in paint

3. Selenium—used in photocopiers and multivitamins

4. Tellurium and polonium are also oxygen group elements

Oxygen Group .55

Oxy

gen

Gro

up

F. Synthetic Elements—scientists create elements not usually found on Earth; synthetic elements usually disintegrate quickly1. Uranium can be made into neptunium which

forms plutonium when it disintegrates

2. Plutonium can be changed into americium, which is used in smoke detectors.

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3. Transuranium elements have more than 92 protons and are synthetic and unstable

a. The study of synthesized elements helps scientists to understand the forces holding the nucleus together

b. Element 114 lasted for 30 seconds

c. It combined 114 protons with 175 neutrons

d. It broke apart due to enormous repulsion between the protons

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Why make elements?

• When these atoms disintegrate, they are said to be radioactive.

• Radioactive elements can be useful. For example, technetium’s radioactivity makes it ideal for many medical applications.

• In the 1960s, scientists theorized that stable synthetic elements exist.

• Finding one might help scientists understand how the forces inside the atom work.

Science and History

The Gas that Glows—Neon. Read orally the article on page 594.

Test coming soon.

Make sure your notes are complete and study them.

Homework is due on test day.