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Ch 4
The periodic table
Element organizations:
Patterns in element properties,
groups of elements that share
properties
Contribution to the periodic table
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John Newland
 Arranged elements by properties and increase atomic
mass.
 Rows of similar chemical and physical properties repeated
every 8th element.
 law of octaves.
Contribution to the periodic table
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Dmitric Mendeleev:
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1869
63 elements in a table to show similarities & periodic
trends by increase atomic mass.
Chemical & physical properties w/ symbols of each
element on cards.
Gaps in table, predicted properties of missing elements
(Ga, Sc & Ge)
Not all fit by increasing atomic mass (Te & I), needed to
switch but did not understand why.
Periodic law
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Mosley:
 Identified element & atomic number.
 Arrange elements by increasing atomic number, fix
some of the problems with Mendeleev’s PT
Ramsey:
 Discovered noble gases
Periodic law:
 Repeating physical & chemical properties of
elements change periodically with their atomic
number.
Periodic table organization
(pg 120-121)
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Groups:
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By element’s valence electrons (outer most
electrons) determines chemical properties
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Vertical column of elements in the periodic table.
Elements share chemical & physical properties, same
number valance elements.
s and p block electrons
Periods:
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Horizontal row (same # of occupied energy levels
Period # = occupied energy level
Systematic change properties (metal -> nonmetal)
Section 2: Tour of the P.T.
Metals, Nonmetals & Mettalloids
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Metals: (most elements)
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Shinny appearance (lustrous), durable,
ductile, malleable, good conductors.
D-block called transition metals (G3-G12)
sum of outer s & d electrons = group #
Less reactive metal, nonreactive – free in
nature (Au, Pt, Pd)
Solid at room temperature except Hg
Regions Periodic table
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Main group elements (representative elements):
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Elements in s-block or p-block of the periodic table.
Groups 1, 2, 13-18
Alkali metals (G1):
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Name from metals that react with water to form alkaline
solutions.
Very reactive (1 valence electrons)
Stored in oil, not found free in nature, soft, good
conductors of electricity.
Metal Regions on the P.T.
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Alkaline-earth metals (G2):
 Highly reactive, not found free in nature
 2 valence electrons, harder & higher melting point than
G1
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Lanthanides & actinides
 f-block, rare-earth
Additional metal properties
 Alloys: mixing 2 or more metals-> different properties
than each metal. (brass Cu&Zn harder and corrosion
resistant, sterling silver Ag&Cu used in jewelry, steel
Fe&C
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Nonmetals
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Properties: brittle, dull, brightly colored,
mostly gases at room temperature, poor
conductors, not malleable or ductile.
Hydrogen
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Most common element in the universe
Unique properties, separate classification.
Nonmetals Continue
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Halogens G17
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Most reactive nonmetal, “salt maker”
7 valence electrons, gain 1 electron: meaning they like to
react with group 1.
Noble gases G18
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Inert gases, 8 valence electrons, non reactive.
Helium only needs 2 valence electrons to be considered to
have a full shell.
Metalloids
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Elements that touch the stair case
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Properties of both metals and nonmetals.
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B, Si, Ge, As, Sb, Te
Exception Al
Solid at room temperature, shiny, somewhat malleable,
conduct heat and electricity a little
Mixed groups 13-16
Periodic table trends
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Trend: predicable change in a particular directions.
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Make predictions about the chemical behavior of the
elements
Based on electron configuration.
Trends:
Ionization
Atomic Radii
Electronegativity
Electron Affinity
Melting and Boiling Points
Ionization Energy
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Ionization energy:
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Energy required to remove an electron from an atom or
ion.
Overcome attractive force between protons and
electrons.
Become positive charge (cation)
Atom + IE --> Cation (+) + electron
Trend: IE decrease down group, valence electrons
further from nucleus and electron shielding -> decrease
attractive force between nucleus and valance electrons
IE increases across a period, # of protons and electrons
increase, higher nuclear charge and attractive forces ->
decrease size
PT Trends continue
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Atomic radius:
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Volume occupied by electrons
Measured using bond radius. 1/2 distance from
the center to center of two like atoms that are
bonded together.
Trend: increases down group, increase energy
levels and shielding decreases effective nuclear
charged “felt” by valance electrons.
Decreases across period: across period increase
# protons and electrons, shielding does not play a
major role. Increase nuclear charge and
attraction to electrons.
PT trends continue
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Electronegativity:
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Measure of the ability of an atom in a chemical
compound to attract electrons.
Know the strength of attraction -> predict chemical and
physical properties.
Linus Pauling: scale of values, reflect how much an atom
attract electrons. Increase value, increase attraction.
Trend: decrease down groups, electron shielding
decreases attraction between valence electrons &
effective nuclear charge, increase size and decrease
attraction.
Increases across periods, increase # protons & electrons
(electron shielding no change) -> increase effective
nuclear charge -> electron attracted greater.
PT trend continue
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Ionic size:
 Increase effective nuclear charge and attraction.
 Cation decrease across period, anions decrease across
period.
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Electron affinity:
 Gain electrons from neutral atom.
 Increase from low left to upper right of the periodic table
 Due to electron shielding and effective nuclear charge.
Melting & boiling pt trends
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Across period:
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2 peaks as d&p orbital fill
Increase # electrons -> stronger bonds between
atoms -> more energy to melt or boil.
1st peak in d-block when orbital about 1/2 filled.
As decrease # of unpaired electrons-> decrease
attraction.
2nd peak in p-block when orbital about 1/2 filled.
Problem
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Arrange the following atoms by
increasing atomic size,
electronegativity, ionization energy and
electron affinity.
Si, Ba, O, and Ge
Elements come from?
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92 naturally occurring elements
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Tc (technetium, Pm (promethium) & Np (neptunium) not
found on earth but detected in spectrum of stars.
Most atoms in living things contain 6 elements
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C,H,O,N,P and S
Mass  to energy
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Transmutations
  one element to another, nuclear reactions.
 Synthetic elements: transuranium elements with more than
92 protons.
 Particle accelerators (cyclotron) make super heavy elements.
Synthetic Elements:
 Synthetic elements: transuranium elements with more than
92 protons
 Particle accelerators make super heavy elements. Called
Cyclotron.
 Island of stability encountered around element 114.