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Periodic Table Unit
John Newlands



John Newlands organized his known
elements by atomic mass.
In studying the elements, he found the
chemical/physical properties repeat every 8
elements.
Law of the Octaves
Dmitri Mendeleev
•
Mendeleev noticed that when the elements were arranged in
order of increasing atomic mass, certain similarities in their
chemical properties appeared at regular intervals.
•
Repeating patterns are referred to as periodic.
•
Mendeleev created a table in which elements with similar
properties were grouped together—a periodic table of the
elements
Dimitri Mendeleev
Columns of
elements with
similar
properties
Rows of
elements with
similar
properties
In columns
by increasing
atomic mass
In rows
by
increasin
g atomic
mass
Predicted elements before
they were actually
discovered
Omnipotent? Genius? ..or Astute?
Henry Moseley
The physical and chemical properties of an
element is a function of their atomic number
Periodic Law
When arranged accordingly similar properties
appear at regular intervals
Periodicity
Actually
arranged by
the number of
protons in the
nucleus or
atomic number
The Modern Periodic Table

The Periodic Table is an arrangement of the elements in order
of their atomic numbers so that elements with similar properties
fall in the same column, or group.

A vertical column in the periodic table is called a group or
family. Elements have similar chemical properties due to their
valence electrons, so elements in the same group/family have
the same number of valence electrons

A horizontal row in the periodic table is called a period.
Elements in the same period/row have the same number of
energy levels or orbitals.
Valence Electrons

The electrons located in the last energy level
8
1
2
3
2
4
5
6
7
Lewis Dot Diagrams
• Diagram showing the valence e- in an atom
H
1 valence e-
N
5 valence e-
Mg
2 valence e-
S
6 valence e-
e-
I
7 valence e-
Xe
8 valence e-
Al
C
3 valence
4 valence e-
Divided into:
Four blocks: (s, p, d and f)
Four Regions: (metals, nonmetals, metalloids, noble gases)
Modern Periodic Table
Main group elements are in the s & p blocks – electron
configurations of main group elements are regular &
consistent
Properties
Metals
•Malleable
•Ductile
•Conductive (heat and
electricity)
•Lustrous (shiny)
•Usually solids at
room temperature
Modern Periodic Table
Non-Metals
Properties
•Non-conductive
(heat and electricity)
•Usually gases or
brittle solids at room
temperature
•Bromine is the only
liquid at room
temperature
Modern Periodic Table
Metalloids
Properties
•Semi-conductive
(heat and electricity)
•Display properties of
metals and nonmetals
Modern Periodic Table
Main Group Noble Gases
– Group 18 (8A) Properties
Ar (1894)
He (1895)
Ne (1898)
Kr (1898)
Xe (1898)
Rn (1900)
•Once thought to be
Inert or chemically
unreactive
•Full set of electrons
in outer shell
•Low reactivity infers
that the full outer
shell is most stable
*synthetic
Modern Periodic Table
Main Group Halogens –
Group 17 (7A)
Properties
Cl (1774)
I
(1811)
Br (1826)
F (1886)
*At (1940)
•Highly reactive group
of nonmetals
•React with most metals
to produce salts- “salt
makers”
•When they react, gain
single electron to form
full outer shell
*synthetic
Modern Periodic Table
Main Group
Alkali Metals (Group 1)
Na (1807)
K (1807)
Li (1817)
Cs (1860)
Rb (1861)
*Fr (1939)
Properties
•Extremely reactive
•React with water to make alkaline
solutions (basic)
•Never found as pure elements due
to their high reactivity
•Readily give up their single valence
electron to form stable noble gas
configuration
Modern Periodic Table
Main Group
Alkaline Metals
Sr (1789)
Be (1798)
Mg (1808)
Ca (1808)
Ba (1808)
Ra (1898)
Properties
•Less reactive than
alkali metals, yet still
very reactive and
found as compounds
in nature
•Readily lose 2
valence electrons to
form stable noble gas
configuration ions
Modern Periodic Table
Transition Metals
Properties
•Called d-block elements
•Less reactive metals than alkali and
alkaline earth metals
•Members in each group do not have
identical outer shell configurations
•Good conductors of heat/electricity.
Malleable and ductile
Modern Periodic Table
Lanthanides
Properties
•Called f-block elements
•Lanthanides follow element
lanthanum
•Actinide follow element acintium
Actinides
Modern Periodic Table
Hydrogen
(1766)
Properties
•Highly reactive
•Non-metal
•Class to itself
•Most common
element in universe
Coloring the Periodic Table









Hydrogen – Yellow
Alkali Metals – Pink
Alkaline Earth – Blue
Halogens – Red
Noble Gases – Purple
Transition – Light Green
Other Metals – Dark Green
Other Nonmetals- Brown
Label Lanthanides &
Actinides
Create a key for your table
(example):
Metals
Alkali
Alkaline Earth
Transition
Other
Periodicity

Similar properties appearing at
regular intervals
1.
2.
3.
4.
5.
6.
Atomic Radius
Valence Electrons
Ionization Energy
Electron Affinity
Ionic Radius
Electronegativity
Atomic Radius – Distance from center of
atom to outer electron cloud

Atoms become larger as we move
from top to bottom as we increase
our number of shells. Inner
electrons shield outer electrons
from the pull.

Atoms become smaller as we
move from left to right because of
the nuclear attractive forces.
Atomic Radius Trend
Decreasing Radius
Increasing
Radius
Nuclear Attractive Forces &
Shielding
e-
eP+ P+
P+ +
P+
P
P+
+
P+ P+ P
e-
e-
The nucleus (+)
pulls the electron
(-) close to the
core.
The further the
electron is away
from the nucleus,
the weaker the
nuclear pull.
Atomic Radius - Graph
All elements prefer a noble gas
configuration
Elements will either lose or gain
electrons to achieve this
configuration
What would be easier?
Gain
Lose
Gain
Gain
or 3
1
2
Lose
2
Electrons
4Electrons
Electron
Electron
Electrons
Electrons
Ion – any element that loses or gains electron(s)
3
Li
6.941
1s22s1
eep+ p
p+
+
e-
Cation
Li+
1s2 = [He]
Ion – any element that loses or gains electron(s)
8
O
15.9994
1s22s22p4
eeee-
e-
O2-
ee-
+
p+ +p p+
p p+ p+
ep+ p+
e- e
e
Anion
1s22s22p6 = [Ne]
Ionization Energy Trend
Ionization energy is the energy required to take an electron from an
atom or ion.
The more energy required, the less likely it will lose eIncreasing I.E.
Decreasing
I.E.
Electron Affinity Trend
Electron Affinity is the energy change that
occurs when a neutral atom gains an electron
The more energy released… more likely it will gain eIncreasing E.A.
Decreasing
E.A.
Ionic Radius


Ions of atoms become
larger as we move from
top to bottom
Cations (positive ions) are
generally smaller than the
neutral atom because
they lose an entire
valence shell!
Ionic Radius

Ions of atoms become
smaller as we move from
left to right

Anions (negative ions) are
generally larger than the
neutral atom. Additional
electrons added, but not
protons – increasing the
Ionic Radius Trend
Decreasing Ionic Radius
Increasing
Ionic
Radius
e-
Electronegativity
The ability of an atom to attract electron(s)
Na
Cl
Which atom has more electronegativity?
Na
e-
Cl
Electronegativity Trend
Increasing Electronegativity
Decreasing
Electronegativity
SUMMARY
Group Trends
Atomic size generally increases as you
move down a group of the periodic table.
Why?
As you descend, electrons are added to
successively higher principal energy levels
and the nuclear charge increases. The
outermost orbital is larger as you move
downward.
Periodic Trends
Atomic size generally decreases as you
move from left to right across a period.
Why?
As you go across a period, the principal
energy level remains the same. Each element
has one more proton and one more electron
than the preceding element.
The electrons are added to the same energy
level, causing the increasing nuclear charge
to pull them in closer.
Trends in Ionization Energy
When an atom gains or loses an electron, it
becomes an ion.
The energy required to overcome the attraction of
the nuclear charge and remove an electron from a
atom is called the ionization energy.
Removing one electron results in the formation of a
positive ion with a 1+ charge.
Na(g)
Na+(g) + e-
Summary Paragraph
Conclusion
1. Why does atomic radius change as it does?
2. Why does the ionization energy change as it
does?