The Periodic Table of the Elements

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The Periodic Table of the Elements
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Classification of Elements

• Pure substances are either compounds or elements.
• Compounds can be broken down into simpler
  substances, but elements cannot because they are
  made of only one kind of atom.
• In the last three centuries, new technologies led
  scientists to try to identify all of the existing
  elements and group them into similar categories.
  
• Currently, scientists have identified 112
  different elements. 92 of them occur naturally,
  and 20 are man-made. Scientists build
  super-heavy atoms to test the limits of atomic
  structure.

• During the eighteenth and nineteenth centuries,
  scientists noticed that some elements behaved
  like other elements.
• By comparing the behaviors of elements,
  scientists identified several groups of elements.
• Other scientists of that time were able to
  determine the relative atomic masses of
  different elements.
• These discoveries led to the development of the
  Periodic Table of the Elements, which is an
  important tool of chemists.

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The First Periodic Table

• Dmitri Mendeleev is known as the father of the
  Periodic Table.
• He was born in Russia in 1834. As were many
  other scientists of the time, Mendeleev was
  interested in discovering if a pattern existed
  relating the known elements.
• Mendeleev discovered that the physical and
  chemical properties of the elements occurred in a
  regular repeating patternthe Periodic Law.
• He published his Periodic Table of the Elements
  in 1869, the first table that successfully
  summarized the relationships between the
  elements.

• In this table, he arranged the known elements in
  ascending order according to their relative
  atomic masses, beginning with Hydrogen.
• Mendeleev also arranged the elements in columns
  according to their physical and chemical
  properties.
• Mendeleevs table pointed out some errors in
  accepted atomic weights, and also predicted the
  existence and properties of elements not yet
  discovered.
• Mendeleevs table did not include any of the
  noble gases, because none of them had been
  discovered.

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Revision of Mendeleevs Table

• In Mendeleevs table, there were some elements
  that appeared to be in the wrong group if
  arranged strictly by increasing atomic weight.
  As more elements were discovered after
  Mendeleevs death, a few more misplaced
  elements appeared.
• Some elements, such as Ni, were placed in the
  wrong groups because of multiple valence numbers
  or errors in the calculation of their atomic
  weights.
• In 1914, Henry Moseley discovered the
  significance of atomic number, the number of
  protons in the nucleus of an atom.

• When the Periodic Table was revised, arranging
  the elements by ascending atomic number, the
  inconsistencies and errors in the table vanished.
• The Modern Periodic Table of the Elements has
  been modified so that the elements are now
  arranged by atomic number, rather than atomic
  weight.
• The Table has seven horizontal rows, called
  periods, and a number of vertical columns called
  groups or families.
• Elements in the same period have the same number
  of occupied energy levels.
• Elements in the same group or family have similar
  properties.

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Metals, Nonmetals, and Metalloids

• There are 92 naturally occurring and 13 man-made
  elements listed on the Periodic Table, with space
  left for future creations.
• These elements can be divided into three basic
  types, according to their chemical and physical
  properties metals, nonmetals, and metalloids.
• Most of the elements are metals. Characteristics
  of metals include high luster, high
  malleability, high ductility, good conductivity
  of heat and electricity, and have high melting
  and boiling points. Metals tend to lose
  electrons in chemical bonding, forming positive
  ions.
• Metals are found on the left side of the Periodic
  Table.

• Nonmetals are found on the right side of the
  Periodic Table.
• Nonmetals are generally dull, brittle,
  non-malleable, non-ductile, with low melting and
  boiling points. Many are gases at room
  temperature. They are non-conductors of heat and
  electricity.
• Nonmetals form negative ions because they tend to
  gain electrons during chemical bonding.
• Metalloids have some of the properties of metals
  and some properties of nonmetals. They are found
  between metals and nonmetals in the Periodic
  Table, next to the zigzag line.

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The Alkali Metals Group IA

• The Alkali Metals are found in the first group of
  the Periodic Table. They are a group of elements
  that are so reactive that they are always found
  combined with other elements in nature.
• The reason that these elements are so reactive is
  that they only have one electron in their outer
  shell, which they lose when bonding with other
  elements, to get a full outer shell of electrons.
  The alkali metals form 1 ions.
• Alkali Metals are malleable and ductile, good
  conductors of heat and electricity, but are very
  soft.
• The alkali metals include Lithium, Sodium,
  Potassium, Rubidium, Cesium, and Francium.
• Alkali metals can explode when in contact with
  water.
• Cesium and Francium are the most reactive in this
  group.
• Francium is the most reactive of all metals.
• Although Hydrogen is a nonmetal, it is often
  listed with this group because it has one
  electron in its only energy level. Hydrogen is
  highly reactive but only forms covalent bonds.

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The Alkaline Earth Metals

• The Alkaline Earth Elements are found in the
  second group of the Periodic Table.
• Even though they are not as reactive as the
  alkali metals, the alkaline earth metals are
  highly reactive, and are not found in the
  elemental state in nature.
• Each of the alkaline earth metals has two
  electrons in its outer energy level. Alkaline
  earth metals lose their two valence electrons and
  form 2 ions when bonding.
• The alkaline earth elements include Beryllium,
  Magnesium, Calcium, Strontium, Barium, and Radium.

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The Boron Family

• The Boron Family is the third group on the
  Periodic Table. The members of this family have
  three electrons in their outer shell. Although
  Boron is never found uncombined in nature, some
  of the other members of this family sometimes
  are.
• Members of the Boron Family tend to lose three
  electrons and form 3 ions.
• Boron is a metalloid, and all other group members
  are metals.
• Aluminum is found in this group. It is the most
  abundant metal on Earth. It is generally found
  in nature as aluminum oxide.
• Other elements found in this family are Gallium,
  Indium, and Thallium.
• Although Boron is a metalloid, all other elements
  in this family are metals.

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The Carbon Family

• The Carbon family is the fourth group, and
  contains one nonmetal, two metalloids, and two
  metals. All members of the carbon family have
  four electrons in their outer energy level.
  Members of this family include Carbon, Silicon,
  Germanium, Tin, and Lead. Members of this family
  tend to form covalent bonds.
• Carbon is the sixth most abundant element in the
  universe, but not as common on Earth.
• Carbon exists in several bonding forms such as
  graphite and diamonds. C-14 is used in
  radiological dating of some fossils.
• It can form four covalent bonds with other
  elements and even other carbon atoms, resulting
  in an almost infinite number of carbon-containing
  compounds. Life on earth would be impossible
  without carbon.
• Silicon is also found in the Carbon Family. It
  is the second most abundant element in the
  Earths crust, and is used in solar-electric
  cells and semi-conductors. Germanium is also
  used in electronic devices. Tin and lead have a
  number of uses.

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The Nitrogen Family

• The Nitrogen Family is the fifth group and
  contains two nonmetals, two metalloids, and only
  one metal. They all have five electrons in their
  outer energy level. They tend to gain three
  electrons when forming ionic bonds, and form -3
  ions.
• Nitrogen makes up about 4/5 of the Earths
  atmosphere, and is a colorless, odorless gas at
  room temperature. It is a nonmetal. Nitrogen
  forms many compounds with oxygen, such as NO2 and
  N2O.
• Phosphorus occurs naturally in solid form as red
  phosphorus or white phosphorus. It is highly
  reactive and will burst into flame in the
  presence of air. It is stored under water.
• Arsenic is a metalloid, and is used in the
  semiconductor industry and in manufacturing. It
  is highly poisonous and is used in weed killer
  and rat poison.
• Antimony is a hard brittle metalloid used in
  electronics. It is, like arsenic, highly
  poisonous.
• Bismuth is the heaviest naturally occurring
  element that is not radioactive. It has a
  variety of uses from Pepto-Bismol to paint
  pigments, to electrical solder and the heads of
  fire sprinkler systems.

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The Oxygen Family

• Members of the Oxygen Family all have six
  electrons in their outermost energy level. The
  Oxygen Family is the sixth group on the Periodic
  Table and contains three nonmetals and two
  metalloids. There are no metals in the Oxygen
  Family.
• Members of the Oxygen Family tend to gain two
  electrons and form -2 ions, when bonding
  ionically.
• Oxygen is the most common element in the Earths
  crust and makes up 1/5 of the Earths atmosphere.
  It is a colorless, odorless gas at room
  temperature. All elements except the noble gases
  can form compounds with oxygen.
• Sulfur is a yellow solid at room temperature.
  Sulfur is in sulfuric acid and also in acid rain.
  It is in the gas H2S, which smells like rotten
  eggs.
• Selenium is a semiconductor that is sensitive to
  light, so it is often used in light sensors.
• Tellurium is a brittle metalloid used in blasting
  caps.
• Polonium is radioactive and was discovered by
  Marie Curie. It has few commercial uses.

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The Halogens

• All members of the Halogen Group have seven
  electrons in their outer energy level. They are
  the seventh group on the Periodic Table. This
  group contains four nonmetals and one metalloid.
  There are no metals among the halogens.
• Because they only need one electron to complete
  their outer energy level, they are the most
  reactive of the nonmetals. They gain one
  electron and form -1 ions when bonding ionically.
  
• Fluorine is the most reactive nonmetal and is
  never found alone in nature. It is a poisonous
  greenish-yellow gas at room temperature.
  Fluorine compounds are added to many water
  systems because they prevent tooth decay. Teflon
  is a fluorocarbon compound.
• Chlorine is not as reactive as fluorine, but is
  also a reactive poisonous greenish-yellow gas.
  One of its most common compounds is NaCl, table
  salt.
• Bromine is a reddish-brown liquid at room
  temperature. It is often used to disinfect hot
  tubs.
• Iodine is a solid at room temperature that turns
  to a purple gas when heated. It is needed in
  your diet to keep your thyroid gland functioning
  properly.
• Astatine is a radioactive metalloid, but not much
  is known about its properties.

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The Noble Gases

• The noble gases are the eighth group on the
  Periodic Table, and all of the members of this
  group are unreactive because their outer electron
  shell is already full.
• Helium is the second lightest and second most
  abundant gas in the universe, but is relatively
  rare on Earth. Helium has two electrons in its
  only energy level. No compounds of Helium are
  known. It is used in balloons and blimps.
• Neon is the best known of the noble gases because
  of its use in decorative lighting fixtures. It
  forms no compounds.
• Argon is used to fill incandescent light bulbs to
  keep the filament from burning up. It is also
  used in welding.
• Krypton is not a green solid that hurts Superman.
  It is an unreactive gas used in bright strobe
  lights and airport runway lights.
• Xenon is a gas that is also used in strobe
  lights. It can be forced to react with fluorine,
  but is ordinarily unreactive.
• Radon is a glowing yellow radioactive noble gas
  that is considered to be a health hazard if
  breathed in large amounts. It is used in cancer
  treatments.

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The Transition Metals

• The Transition Metals are the elements found on
  the Periodic Table between the Alkaline Earth
  Metals and the Boron Family.
• While the Transition Metals all have no more than
  2 electrons in their outer energy level, their
  next energy level is incompletely filled.
• The properties of the Transition Metals depend on
  the electron configuration of the outer two
  energy levels.
• Transition elements form alloys easily. A
  copper-tin alloy is for mirrors and copper-zinc
  makes brass. Except for copper, the transition
  metals are all shiny and white, with high melting
  points and high densities.
• Many of the most commonly known metals, such as
  gold, silver, mercury, iron, copper and nickel
  are in this group.

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The Rare Earth Elements

• There are 30 Rare Earth Elements. They are all
  metals, and they are divided into two sets The
  Lanthanide Series begins with element 57,
  Lanthanum and ends with element 71 Lutetium.
  The Actinide Series begins with element 89
  Actinium and ends with element 103 Lawrencium.
  
• One element of the Lanthanide Series and most of
  the elements of the Actinide series are man-made.
  Many are radioactive.
• All of the Rare Earth elements are found in Group
  3 of the Periodic Table in the sixth and seventh
  periods.

La Ce Pr Nd Pm Sm Eu Gd Tb
Dy Ho Er Tm Yb Lu
Lanthanide Series
Ac Th Pa U Np Pu Am Cm Bk
Cf Es Fm Md No Lr
Actinide Series
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A Representative Block on the Periodic Table

• Each block on the Periodic Table contains
  valuable information about the element listed.
• The name of the element is often (but not always)
  listed.
• The elements chemical symbol is always listed.
  This is either one or two letters. The first is
  always capitalized and the second (if there is
  one) is never capitalized.
• The Atomic Number tells how many protons are in
  the nucleus of an atom of that element.
• The Atomic Mass tells the average mass of one
  atom of that element in atomic mass units. It
  can be rounded off to determine the elements
  mass number.

Atomic Number
ChemicalSymbol
Name of Element
Atomic Mass
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Periods, Families, and Electron Configuration

• There are seven periods on the modern Periodic
  Table.
• If an element appears in the third period (like
  Magnesium), this means that in its lowest energy
  state, the atoms electrons are in the first
  three periods.
• Being located in the third period also means that
  the atoms first two energy levels are full.
• The first energy level can hold 2 electrons. The
  second energy level can hold eight electrons.
• Magnesium appears in the Alkaline Earth Family,
  in the IIA column of the Table. All elements in
  the IIA column have 2 electrons in their
  outermost energy level.
• Elements in the IA column have 1 electron in
  their outside energy level, elements in the VA
  column have 5 electrons in their outside energy
  level, and so forth.
• Elements in Column VIIIA are inert. Their
  outside energy levels are full, so they have no
  need to react to form compounds with other
  elements.