ChemPhys, Chapter 19

1
Chapter 19 Elements and Their Properties
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.

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)

4
Metals Form Ionic Bonds

• Metals can usually lose between 1 and 3 electrons
  to form ions.
• Examples
• Ag1
• Fe2
• Fe3

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

15
Metals in the Earths Crust

• Gold, silver, and platinum are found as the metal
  in the earths 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.

16
Chapter 19, Section 1 Review

• Describe the properties of a typical metal.
• Identify the alkali metals and the alkaline earth
  metals.
• Locate and describe the three separate groups of
  transition metals.

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.

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.

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.

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.

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.

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.

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.

24
Chapter 19, Section 2 Review

• Is hydrogen a metal or a non-metal?
• What are the properties of the halogens?
• What are the properties and uses of the noble
  gases?

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.

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.

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

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.

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.

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.

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.

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)

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.

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.

35
Synthetic Elements

• All synthetic elements are radioactive.
• Radioactive elements have uses in medical
  procedures.
• Radioactive americium is useful in smoke
  detectors. (Dont throw a smoke detector away!
  It contains hazardous waste.)

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.

37
Chapter 19, Section 3 Review

• What are the differences between metals,
  non-metals, and metaloids?
• What is the nature of allotropes?
• What is the significance of differences in
  crystal structure in carbon?
• What is the importance of synthetic elements?