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Chem-Phys, Chapter 19Page 1
Chapter 19 – Elements and Their Properties
Chem-Phys, Chapter 19Page 2
Properties of Metals
• 6,000 years ago, gold was the first metal used by man. Later, man used copper, silver, tin and iron.
• Metals are found on the left side of the periodic table (left of the zig-zag line).
• Metals are good conductors of heat and electricity.
Chem-Phys, Chapter 19Page 3
Properties of Metals
• Most metals are solids.
• Metals reflect light.
• Metals are malleable (they can be pounded into a thin sheet)
• Metals are ductile (they can be pulled into a wire)
Chem-Phys, Chapter 19Page 4
Metals Form Ionic Bonds
• Metals can usually lose between 1 and 3 electrons to form ions.
• Examples:– Ag1+ – Fe2+ – Fe3+
Chem-Phys, Chapter 19Page 5
Metals Form Metallic Bonds
• Metals are held together with metallic bonds.
• The atoms of the metal is surrounded by a “sea” of electrons.
• So, layers of metal atoms can shift without losing strength.
• The “sea” of electrons gives metals their conductivity.
Chem-Phys, Chapter 19Page 6
Alkali Metals
• The alkali metals are in the first column of the periodic table. This column is called Group 1.
• All Group 1 elements have one outer electron which they lose when they form bonds. Na becomes Na+ in NaCl, K becomes K+ in KBr, etc.
• Alkali metals are the most reactive of the metals. They react with water.
Chem-Phys, Chapter 19Page 7
Uses of Alkali Metals
• Compounds of sodium and potassium are necessary for life.
• Cadmium and rubidium are used in some photocells.
• Francium is radioactive and very rare. In a radioactive element, the nucleus breaks down and gives off particles and energy.
Chem-Phys, Chapter 19Page 8
Alkaline Earth Metals
• Alkaline earth metals are in Group 2 of the periodic table.
• They are shiny, malleable, and ductile.
• Each atom of a alkaline earth metal has two outer electrons which it loses when it forms bonds. So, Ca becomes Ca2+ when it forms CaCl2, Mg becomes Mg2+ when it forms MgSO4, etc.
Chem-Phys, Chapter 19Page 9
Uses of Alkaline Earth Metals
• Fireworks get their color from alkaline earth metals: strontium – red, magnesium – white, Barium – green, etc.
• Magnesium is used in airplanes, ladders, etc.
• Chlorophyll contains magnesium• Calcium is found in marble and is
necessary for strong bones.• Barium is used in medical procedures.
Chem-Phys, Chapter 19Page 10
Transition Elements
• The transition elements are in Groups 3 through 12 on the periodic table.
• These metals are at the “transition” between Group 2 and Group 13.
• These metals are the most familiar:– Iron Fe Silver Ag– Copper Cu Gold Au– Nickel Ni Zinc Zn
Chem-Phys, Chapter 19Page 11
Iron, Cobalt, Nickel
• Iron is the most widely used of all metals.
• Iron is the second most abundant metal behind aluminum.
• Steel is a mixture of iron and other metals such as cobalt and nickel.
• Nickel is used in nickels!
• Nickel is added to some metals to give them strength or to protect them.
Chem-Phys, Chapter 19Page 12
Copper, Silver, and Gold
• Copper, Silver and Gold are in Group 11 on the periodic table.
• Coins are made of copper, silver, and gold. (U.S. not using gold or silver anymore.) These are called the coinage metals.
• Copper used in electrical wiring.• Silver used in photographic film.• Gold and silver are used in jewelry.
Chem-Phys, Chapter 19Page 13
Zinc, Cadmium, and Mercury
• Zinc is used to protect other metals because it forms a thin protective oxide later.
• Cadmium is used in re-chargeable batteries.
• Mercury is the only metal that is a liquid at room temperature. It is used in thermometers and fluorescent lights. Mercury forms toxic compounds.
Chem-Phys, Chapter 19Page 14
Inner Transition Elements
• The inner transition elements are the two disconnected rows of elements at the bottom of the periodic table.
• The lanthanides follow the element lanthanum. These elements are used in color TV screens.
• The actinides follow the element actinium. They are all radioactive and used in nuclear reactors and nuclear bombs.
Chem-Phys, Chapter 19Page 15
Metals in the Earth’s Crust
• Gold, silver, and platinum are found as the metal in the earth’s crust.
• All other metals are found as ores. An ore is a compound of the metal.
• Before the metal can be recovered, metal ore must be separated from clay and rock.
• Ore is put through a chemical process, usually involving heat, to recover the metal.
Chem-Phys, Chapter 19Page 16
Chapter 19, Section 1 Review
1. Describe the properties of a typical metal.
2. Identify the alkali metals and the alkaline earth metals.
3. Locate and describe the three separate groups of transition metals.
Chem-Phys, Chapter 19Page 17
Non-metals
• Non-metals are found to the right of the zig-zag line.
• Non-metals are usually gases or brittle solids.
• Non-metals are not shiny and do not conduct electricity or heat well.
• Non-metals are usually not ductile or malleable.
Chem-Phys, Chapter 19Page 18
Bonding in Non-metals
• Non-metals form both covalent and ionic bonds.
• Non-metals usually form ionic bonds when they react with metals (NaCl, AgBr, etc.)
• When bonded with other non-metals, non-metals usually form covalent bonds: H2O, NH3, CH4, etc.
Chem-Phys, Chapter 19Page 19
Hydrogen
• About 90% of the atoms in the universe are hydrogen.
• When water is broken down by electrolysis, diatomic hydrogen, H2, and diatomic oxygen, O2 are released.
• Hydrogen can give up one electron like the alkali metals.
• Hydrogen is considered a non-metal.
Chem-Phys, Chapter 19Page 20
Halogens
• The halogens are in Group 17.
• Halogen light contain small amounts of bromine or iodine.
• Chlorine is added to drinking water to kill germs.
• Fluoride is added to drinking water and toothpaste to strengthen teeth.
Chem-Phys, Chapter 19Page 21
Halogens
• When a halogen reacts with a metal, they form a salt. For example, sodium and chlorine make sodium chloride, NaCl, table salt.
• Fluorine is the most chemically active element. Hydrofluoric acid (HF in water) is used to etch or frost glass.
Chem-Phys, Chapter 19Page 22
Halogens
• The odor you smell near a swimming pool is usually chlorine.
• Bromine is the only non-metal that is a liquid at room temperature.
• Iodine is a shiny purple-gray solid recovered from seawater.
• Iodine can change directly from a solid into a gas. This is called sublimation.
Chem-Phys, Chapter 19Page 23
Noble Gases
• The noble gases are found in Group 18.
• The noble gases occur as single atoms. They almost never react with anything to form chemical compounds.
• The noble gases are useful because they are so stable.
• Neon, argon, and krypton are used in electric lights and to make lasers.
Chem-Phys, Chapter 19Page 24
Chapter 19, Section 2 Review
1. Is hydrogen a metal or a non-metal?
2. What are the properties of the halogens?
3. What are the properties and uses of the noble gases?
Chem-Phys, Chapter 19Page 25
Properties of Metalloids
• The metalloids are the elements touching the zig-zag line at the right of the periodic table (aluminum is a metal).
• The metalloids have properties between those of non-metals and metals.
• Some metalloids are semi-conductors and useful in making transistors.
Chem-Phys, Chapter 19Page 26
Boron
• Boron is contained in borax, a household laundry product.
• Boron is also in boric acid, a mild antiseptic.
• Boranes are found in jet and rocket fuel.
Chem-Phys, Chapter 19Page 27
Carbon Group
• Carbon is a non-metal.
• Silicon and germanium are metaloids.
• Carbon is an element essential for life.
• Silicon occurs in two different forms that have different molecular structures, called allotropes:– A hard, gray solid– A brown powder
Chem-Phys, Chapter 19Page 28
Carbon Group
• Silicon and germanium are semiconductors used in making the electronic devices and computers we all use.
• Tin is used in tin cans to prevent corrosion.
• Tin is combined with other elements to make bronze and pewter.
• Lead has many uses.
Chem-Phys, Chapter 19Page 29
Allotropes of Carbon
• Carbon appears in three forms, called allotropes.
• Diamond – a clear, extremely hard form of carbon.
• Graphite – a black solid used in pencil lead.
• Buckminsterfullerene – spheres of carbon containing 60 atoms of carbon.
• Nanotubes of carbon.
Chem-Phys, Chapter 19Page 30
Nitrogen Group
• The nitrogen family is in Group 15.
• All these elements have five electrons in the highest level orbital which are available for bonding.
• Nitrogen is an element essential for life. Nitrogen is contained in amino acids.
Chem-Phys, Chapter 19Page 31
Nitrogen Group
• Phosphorous is a non-metal with three allotropic forms.
• Phosphorous is used in fertillizers.
• Antimony is a metalloid.
• Bismuth is a metal. Bismuth is used in alloys and used to lower their melting point.
Chem-Phys, Chapter 19Page 32
Oxygen Group
• The oxygen family is in Group 16.
• Oxygen is essential for life. We need oxygen to breath.
• Oxygen occurs in two allotropic forms:– Oxygen gas, O2
– Ozone gas, O3, (“fresh” smell after a thunderstorm)
Chem-Phys, Chapter 19Page 33
Oxygen Group
• The other oxygen group elements are non-metal selenium, and metalloids tellurium, and polonium.
• Selenium is necessary for life but toxic at high levels.
Chem-Phys, Chapter 19Page 34
Synthetic Elements
• All elements above uranium (called the transuranium elements) are man-made.
• In a nuclear reactor, neutrons bombard uranium to make neptunium. Neptunium when bombarded by neutrons becomes plutonium. Plutonium when bombarded by neutrons becomes americium.
Chem-Phys, Chapter 19Page 35
Synthetic Elements
• All synthetic elements are radioactive.
• Radioactive elements have uses in medical procedures.
• Radioactive americium is useful in smoke detectors. (Don’t throw a smoke detector away! It contains hazardous waste.)
Chem-Phys, Chapter 19Page 36
Synthetic Elements
• Scientists also make synthetic elements to better understand how the nucleus operates.
• Scientists are looking for more stable elements above atomic number of 103.
• Element 114 has a half life of 30 seconds which is very long for these elements.
• Element 118 has been made.
Chem-Phys, Chapter 19Page 37
Chapter 19, Section 3 Review
1. What are the differences between metals, non-metals, and metaloids?
2. What is the nature of allotropes?
3. What is the significance of differences in crystal structure in carbon?
4. What is the importance of synthetic elements?