Transcript Periodic Chart - Davidson County Schools

Periodic Chart
Contributors to the
Periodic Chart
Stanislao Cannizzaro
(1826-1910)
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Presented method
for measuring
atomic masses
Did not construct a
periodic chart
Dmitri Mendeleev
(1834 – 1907)
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Russian Chemist
Organized elements
according to
properties
“Father of the Periodic
Chart”
Created the “Periodic
Table of the Elements”
(1869)
First Periodic Chart - Draft
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Noticed when
elements were
arranged in order of
increasing atomic
masses, similar
properties appeared
at regular intervals
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Left spaces for
elements to be
discovered later.
Mendeleev’s 1869 Periodic Table
Henry Gwyn-Jeffreys Mosley
(1887 – 1915)
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Discovered why some
elements could not be
arranged by atomic mass
Lead to the elements
being listed by atomic
number instead of mass
Can be seen on the
modern periodic chart
Killed in battle in WWI
Periodic Chart Arrangement
Period 1
Period 2
Period 3
Period 4
Period 5
Period 6
Period 7
Period 6
Period 7
Periodic Chart Arrangement
Group 18
Group 17
Group 16
Group 15
Group 14
Group 13
Group 12
Group 11
Group 10
Group 9
Group 8
Group 7
Group 6
Group 5
Group 4
Group 3
Group 2
Group 1
No Group Numbers
Alkali Metals
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Group 1
1 Valence Electron
Extremely Reactive
React with water
more vigorously
moving down
No free elements
Stored in oil
Silver appearance
Soft
Alkali Metals Video
Alkaline Earth Metals
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Group 2
2 valence electrons
Less reactive than
alkali metals
No free elements
Common in earth’s
crust as compounds
More reactive down
the chart
Transition Metals
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d-block elements
Usually 2 valence
electrons – can have
more or less
Groups 3 - 12
Typical metallic
properties
Good conductors of
electricity
Reactivity varies
Found as free
elements
Wide range of melting
points
p- block Elements
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A.k.a – Main group
elements
Metals and
nonmetals
Vary greatly
p- block Elements
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NonMetals
Metals
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A.k.a – Main
Group Elements
Metals and
nonmetals
Vary greatly
Metalloids
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Elements adjacent to
stair-step line
Have characteristics
of metals and
nonmetals
Mostly brittle solids
Intermediate
conductors of
electricity
“semi-conductors”
Boron Group
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All elements under
Boron
3 valence
electrons
Carbon Group
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All elements under
Carbon
4 valence
electrons
Nitrogen Group
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All elements under
Nitrogen
5 valence
electrons
Oxygen Group
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All elements under
Oxygen
6 valence
electrons
Halogens
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7 valence
electrons
Most reactive of
the nonmetals
React vigorously
with metals
forming salts
diatomic
Noble Gases
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8 valence
electrons
Least reactive of
all elements
Will not bond
Lanthanides
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2 Valence
electrons
“Rare Earth
Metals”
Not actually rare
Shiny
Reflective metals
Actinides
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2 Valence
electrons
Very Unstable
1st 4 found in
nature
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Th, Pa, U, Np
radioactive
Trends of the Periodic
Chart
Period and Group
Trends
Atomic Radii
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½ the distance between the nuclei
of adjoining atoms
Atomic Radii – Period Trend
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Decreases
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Decreases as
move across the
chart from LR
Caused by
increasing positive
charge of the
nucleus
Pulls electrons in
tighter
Atomic Radii – Group Trend
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Increase
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Increases as move
down chart from
TB
Outer electrons
are in higher main
energy levels
Atomic Radii – Group Trend
Exception
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Gallium (Ga)
Follows Al
Is actually smaller
than Al
Due to influence of
the d-block
Higher nuclear
charge
Ionization Energy
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Energy required to remove an
electron from an atom
Ion – charged atom
Ionization Energy – Period
Trend
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Increase
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Energy increases
across the chart
from LR
Caused by
increasing nuclear
charge
Nonmetals usually
have higher
ionization energies
than metals
Ionization Energy – Group
Trend
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Decrease
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Usually decrease
from top to bottom
Due to distance
from nucleus
Electron Affinity
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Energy change that occurs when an
electron is acquired by a neutral
atom
Electron Affinity – Period
Trend
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Decrease
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Less Energy from
LR
Halogens gain
electrons most
easily
Love of electrons
= less energy
Electron Affinity – Group
Trend
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No real pattern
No real pattern
All the atoms have
the same number
of valence
electrons
Ionic Radii
½ the distance between the neucli
of two adjoining ions
 Cation – positive ion – loss of one or
more electrons
 Anion – negative ion – gain of one
or more electrons
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Ionic Radii – Period Trend
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Metals
Cations
Non- 
Metals
Anions
Metals on the left
form cations
Nonmetals on the
right form anions
Ionic Radii – Group Trend
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Increase
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Increase moving
down chart from
TB
Outer electrons
are in higher
energy levels
Valence Electrons
Electron available to be gained or
lost
 Will be shared in a chemical reaction
 Are always based on Groups Only
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Valence Electrons
8
7
6
5
4
3
1
Usually 2
2
Usually 2
Electronegativity
Ability of an atom to attract
electrons
 Anions attract
 Cations repel
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Electronegativity – Period
Trend
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Increase
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Increase from LR
Nonmetals more
electronegative
Halogens most
electronegative
Electronegativity – Group
Trend
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No real Pattern
No real pattern
Either decrease as
move down
Some have similar
values
Oxidation Numbers
Shows general distribution of
electrons among atoms
 Metals tend to donate electrons
 Nonmetals tend to accept electrons
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Oxidation Numbers
0
-1
-2
-3
±4
+3
Varies
+2
+1
Usually +2