Transcript The Periodic Table and Periodic Law

The Periodic Table
and Periodic Law
Chapter 6
Section 6.1: Development of the
Modern Periodic Table
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Late 1790’s- Lavoisier compiled a list of 23
elements known at the time
By 1870- 70 known elements
John Newlands
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Arranged elements by increasing atomic mass
Noticed properties repeated every eighth
element (periodic)
Law of Octaves
Dmitri Mendeleev
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Russian
1st periodic table
Organized elements by
properties
Arranged elements by atomic
mass
Predicted existence of several
unknown elements
Element 101 Mendeleevium
(Md)
Henry Moseley
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1913-performs experiments to
determine the atomic number
of the known elements
Afterwards arranges the
elements in the periodic table
listing them by increasing
atomic number instead of by
mass
Periodic Law
When the elements are arranged in
order of increasing atomic number,
there is a periodic repetition of their
physical and chemical properties
The Modern Periodic Table
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Groups- aka families (vertical columns)
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Each group is numbered 1-8 followed by the
letter A or B
Representative Elements- designated with
an A (1A-8A)
Transition Elements- designated with a B
(3B-12B)
18 total groups
elements of any one group have similar
physical and chemical properties
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Periods- horizontal rows
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7 total periods
element properties change as you go across
each row
the pattern of properties repeats from one
period to the next
Classifying the Elements
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Three main classifications for the elements
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Metals
Nonmetals
Metalloids
Metals
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Physical Properties
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Chemical Properties
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Luster (shininess)
Good conductors of heat and electricity
High density (heavy for their size)
High melting point
Ductile (most metals can be drawn out into thin wires)
Malleable (most metals can be hammered into thin
sheets)
Easily lose valence electrons
Corrode easily
Alkali Metals- group 1A elements (except hydrogen)
Alkaline Earth Metals- group 2A elements
Metals Con’t.
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Transition Metals
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Group B elements
Inner Transition Metals
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Lanthanide- used as phosphors (substances
that emit light when struck by electrons)
Actinide
Nonmetals
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Physical Properties
 No luster (dull appearance)
 Poor conductor of heat and electricity
 Brittle (breaks easily) or gaseous
 Not ductile
 Not malleable
 Low density
 Low melting point
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Bromine is the only nonmetal liquid at room temperature
Chemical Properties
 Tend to gain valence electrons
Nonmetals Con’t
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Halogens
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Group 7A
Extremely Reactive
Noble Gases
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Group 8A
Extremely Unreactive
Metalloids
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Bordering the stair-step line
Physical Properties
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Solids
Can be shiny or dull
Ductile
Malleable
Conduct heat and electricity better than
nonmetals but not as well as metals
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Elements in the same group on the
periodic table have similar chemical
properties because they have the same
valence electron configuration
Section 6.3: Periodic Trends
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The electron cloud surrounding the
nucleus is based on the probability and
does not have a clearly defined edge
Atomic size is defined by how closely an
atoms lies to a neighboring atom
Atomic Radii Trend
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Trends within
periods
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Generally decreases
as you move left-toright across a period
(row)
Trends within
groups
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Generally increases
as you move down a
group
Ionic Radius
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An ion is an atom or a bonded group of
atoms that has a positive or negative
charge
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When atoms lose electrons and form
positively charged ions, they always become
smaller
When atoms gain electrons and form
negatively charged ions, they always become
larger
Lose Electrons  Smaller ionic radii
Gain Electrons  larger ionic radii
Ionization Energy (I.E.)
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Ionization Energy- the energy required to
remove an electron from a gaseous atom
1st Ionization Energy- removes the 1st
electron
2nd Ionization Energy- removes the 2nd
electron… and so forth
I.E. is an indication on how strongly an
atom’s nucleus holds onto its valence
electrons
Octet Rule- atoms tend to
gain, lose or share
electrons in order to
acquire a full set of eight
valence electrons
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Octet Rule- atoms tend to gain, lose or share
electrons in order to acquire a full set of eight
valence electrons
 Hydrogen and Helium are exceptions (they’ll be
happy with 2 V.E.)
 Determines the types of ions likely to form
 Elements on the right side tend to gain
electrons
 Elements on the left side tend to lose
electrons
Electronegativity
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Indicates the relative ability of its atoms to
attract electrons in a chemical bond
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Noble gases form very few compounds so
they are left out
In a chemical bond, the atom with the greater
electronegativity more strongly attracts the
bond’s electrons
Atomic radius increases
Ionization energy decreases
Electronegativity decreases
In Summary
Atomic radius decreases
Ionization energy increases
Electronegativity increases
1A
0
2A
3A 4A 5A 6A 7A
Matching Words for Test
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Electronegativity
Ionization energy
Atomic radius
Metal
Transition metal
Anion
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Periodic law
Cation
Period
Group
Electrons
Nonmetal
Homework
 Page
174-175
 #29-#38
 #40-#45
 #47-#76