Chem-Phys, Chapter 19 Page 1 Chapter 19 – Elements and Their Properties.

Chem-Phys, Chapter 19Page 1

Chapter 19 – Elements and Their Properties


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.


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)


Metals Form Ionic Bonds

• Metals can usually lose between 1 and 3 electrons to form ions.

• Examples:– Ag1+ – Fe2+ – Fe3+


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.


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.


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.


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.


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.


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


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.



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?


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.


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.


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


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.


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.


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.


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.


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)


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.


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.


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.)


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.



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?

Chem-Phys, Chapter 19 Page 1 Chapter 19 – Elements and Their Properties.

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Chem-Phys, Chapter 19 Page 1 Chapter 19 – Elements and Their Properties.