Atomic Theory and Structure The Periodic Table

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Atomic Theory and StructureThe Periodic Table

• Discovery of the Atoms and their Properties
• Periodic Table
• Trends in the Periodic Table
• Elements and their Names

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History of the Atom

• From ancient Greek times of philosophy to today's
  technological era of quantum physics, scientists
  have been mesmerized by what is thought to be the
  smallest particle - the atom. In Greek, the
  prefix "a" means "not" and the word "tomos" means
  cut. Thus, atomos or atom means uncuttable or
  undividable.

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It all began with

• All matter is made up of undividable particles
  called atoms.
• There is a void, which is empty space between
  atoms.
• Atoms are completely solid.
• Atoms are homogeneous, with no internal
  structure.
• Atoms vary in 1)Size 2) Shape 3) Weight

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September of 1803

Dalton was the first to propose that elements
would be identified by symbols. He also built on
the research of ancient scientists saying
John Dalton, Father of Modern Atomic Theory
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Daltons Research

• 1.Chemical elements are made of atoms
• 2.The atoms of an element are identical in their
  masses.
• 3. Atoms of different elements have different
  masses.
• 4. Atoms only combine in small, whole number
  ratios.
• 5. Atoms can neither be created nor destroyed.

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J.J. Thompson

• In 1904 JJ Thomas verified the existence of
  positive particles. He visualized that atoms
  were positively charged pudding and the
  negative matter plums were spread throughout
  the pudding.

The Plum Pudding Model
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..then came Ernest Rutherford

• Having worked under JJ Thomas, Rutherford was
  very familiar with the study of the atom.
  Through experiments with radioactive studies he
  proved that atoms had a nucleus. This became
  known as the Gold Foil Experiment due to his use
  of gold foil to reflect the radioactive particles.

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Neils Bohr

• Bohr built onto Rutherfords nucleus devising a
  Planetary Model.

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Pictures of Bohrs Research
The green and red spheres represent the protons
and neutrons of the atom. The orange spheres
represent the electrons.
The charges of the parts in an atom are shown for
a carbon atom.
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Key Definitions of Todays Atom

• Proton positive part of the atom found in the
  center of the atom (nucleus)
• Neutron neutral (no charge) part of the atom
  found in the center of the atom
• Electron- negative part of the atom found
  circling the center of the atom
• Nucleus center of the atom home of the proton
  and neutron has the majority of the mass of the
  atom

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The Periodic Table

• The periodic table was organized over the years
  to provide scientists information about the
  different elements. Both man-made and natural,
  the elements are placed in order of things such
  as atomic mass, atomic number, size and other
  things.

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Dmitrii Mendeleev

• The first periodic table was put together by
  Mendeleev over 130 years ago. He put the
  elements in order of relationships of reactivity
  (how elements react). His table had holes in it
  that allowed for other elements to be discovered
  at a later time.

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Todays Periodic Table

• Mendeleev was correct in his holes on his table.
  Todays table looks very similar to his table.
  It lists the elements in order of their atomic
  number.
• The first 92 elements have been found in nature.
  All other elements have been man-made.

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Parts of the Periodic Table
Nonmetals elements possessing the opposite
characteristics of metals. They are often found
in the gaseous state. Examples Hydrogen,
Oxygen, Nitrogen
Metals- elements possessing similar properties
such as metallic luster, reacting well with
elements other than metals, and easily conducts
electricity. Examples Copper, Potassium, Sodium
Transitional Metals- found between metals and
nonmetals often have properties of both. Ex
Silicon, Boron
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Breaking apart even further

• Groups of elements vertical columns of elements
  on the periodic table
• Chemical Family a group of elements that
  includes the number of the column
• Period of elements horizontal row of elements

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1 H 1.008
ALKALI
3 Li 6.941
METALS
11 Na 22.99
19 K 39.10

• Group IA Characteristics
• The most chemically reactive metals, with the
  exception of Hydrogen, losing their one valence
  electron to non-metals
• Going down the group, the atomic radius and
  density of the elements increase

37 Rb 85.47
55 Cs 132.9
87 Fr (223)
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• Group IIA Characteristics
• These elements are also very reactive, losing
  their two valence electrons to non-metals

4 Be 9012
12 Mg 24.31
20 Ca 40.08
38 Sr 87.62
Alkaline
56 Ba 137.3
Earth Metals
88 Ra 226
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Halogens
9 F 18.9984 17 Cl 35.453 35 Br 79.909 53 I 126.904
85 At (210)

• Group 7A Characteristics
• These elements all form diatomic molecules.
• With the exception of At, they all react with
  metals to form salts containing ions with a 1-
  charge.

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2 He 4.0026 10 Ne 20.179 18 Ar 39.498 36 Kr 83.80
54 Xe 131.30 86 Rn (222)

• Group 8A Characteristics
• These elements exist under normal conditions as
  single-atom gases
• Have little chemical reactivity

Noble Gases
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Metals

• Characteristics
• These have physical properties such as
  conduction of heat and electricity, malleability,
  ductility, and a lustrous appearance
• They tend to loose electrons to form positive
  ions.

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Nonmetals
7 N 14.0067 15 P 30.9738 33 As 74.9216
6 C 12.011 14 Si 28.086
5 B 10.811
8 O 15.999 16 S 32.064 34 Se 78.96 52 Te 127.6

• Characteristics
• These are found in the upper right-hand corner
  of the table.
• Lack the physical properties to deem them
  metals.
• They tend to gain electrons in reactions with
  metals.

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TRANSITION METALS
30 Zn 65.38
48 Cd 112.4
80 Hg 200.6
112 Uub (277)
Characteristics They show great similarities
within a given period and group The last
electrons are added to the d orbital
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Lanthanum Series

• Characteristics
• Electrons fill the 4f orbital
• These elements decrease in size, going from left
  to right

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Actinium Series

• Characteristics
• Members of the transitions metals
• Electrons fill the 5f orbital

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The Periodic Table
Non-Metals
Noble Gases
Halogens
Alkaline Earth Metals
Alkali Metals
Transition Metals
Metals
Lanthanide Series
Actinide Series
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Trends in the Periodic Table

• When studying the periodic table one can tell
  many things about an element just by its location
  on the table. These trends help scientists
  identify new elements and understand why an
  element has different properties.

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Atomic Size

• Atomic size within a group increases as one moves
  vertically down the periodic table.
• Atomic size within a period decreases as one
  moves horizontally right across the periodic
  table.

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Ionization Energy(the energy required to remove
an electron from an element)

• The energy required for elements within a group
  decreases as one moves vertically down the
  periodic table.
• The energy required for elements within a period
  increases as one moves horizontally right across
  the periodic table.
• The most metallic elements (Group IA) have the
  lowest energies of any elements on the periodic
  table.

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Melting Points

• Melting points of elements increase when one
  moves horizontally right across the periodic
  table until about half way across the periodic
  table. After this point the melting points
  decrease when moving right across the periodic
  table.
• Carbon has the highest melting point of any
  element (4100 C)

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Density of Elements

• Densities within a group increase as one moves
  vertically down the periodic table.
• Densities within a period first increase then
  decrease when moving horizontally right across
  the periodic table. The switch occurs near Group
  VIIIB.
• Elements with the greatest densities are at the
  center of Period 6.

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Gathering Information from the Periodic Table

• When one looks at a periodic table, there are
  many letters and numbers that help identify the
  elements and give way to their characteristics.
  Understanding these letters and numbers will
  allow for a better understand of each element.

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Atomic Mass (Mass Number)
1 H 1.01

• The average of all of the masses of the naturally
  occurring isotopes of an element.
• The mass number is the rounded atomic mass. It
  is the number of protons and neutrons found in an
  atom.

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Atomic Number
1 H 1.01

• The number of protons in the nucleus of an atom

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Protons, Neutrons, and Electrons

• of Protons same as the atomic number
• of Electrons same as the atomic number and the
  number of protons
• of Neutrons found by subtracting the atomic
  number from the mass number

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Example
9 F 19.00
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• of Protons _______________
• of Electrons _______________
• of Neutrons _______________

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10 (19 9)
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Names and Symbols of Elements

• Looking at the periodic table reveals the symbols
  of each element. These symbols provide an easier
  way to write out each element rather than writing
  the long word each time. The shortcut in writing
  was devised based upon the origin of the
  elements name. Learning the symbols makes
  recording the scientific data easier.

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Common Elements and Their Symbols
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Common Elements with Unique Symbols