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UNIT VIII
The Periodic Table and Chemical Bonding
Lesson#3
VIII.2 THE PERIODIC TABLE

Organized according to ATOMIC # --- Mendeleev
Genius!
Periodic Law: The chemical properties of the elements
recur periodically when the elements are arranged in
increasing order by their atomic numbers.
A. The Modern Periodic Table
INCREASING REACTIVITY
METALS
Increasing Reactivity
Transition
METALS
Increasing Reactivity
Trends in the Periodic Table:
PERIOD: is the set of all the elements in a given row
going ACROSS the table. [HORIZONTAL]
FAMILY (group): is the set of all the elements in a
given column going down the table. [VERTICAL]
A. The Modern Periodic Table
1
INCREASING REACTIVITY
2
3
4
5
6
7
PERIODS
INCREASING REACTIVITY
A. The Modern Periodic Table
GROUPS
VIII.2 THE PERIODIC TABLE
Metals, Nonmetals, and Semiconductors:

Metals:
 malleable (flatten into sheets)
 ductile
 opaque
 conduct electricity*
 solid at room temp (except.... Mercury )
 Lustre Shiny-ness
*Metals conductivity decreases with an increase in
temp
TEMP
=
CONDUCTIVITY
VIII.2 THE PERIODIC TABLE
Metals, Nonmetals, and Semiconductors:
 Nonmetals


At room temperature: solid, liquid or gas
poor conductors
 Semiconductors


aka “metalloids” or “semimetals”
conductivity increases with an increase in
temp
VIII.2 THE PERIODIC TABLE
VIII.2 THE PERIODIC TABLE
TRENDS:
1.
Properties of elements change from metallic
to nonmetallic going from left to right
More Metallic
More Metallic
VIII.2 THE PERIODIC TABLE
3. The size of the elements radius INCREASES
going across a row and increases going down
a family.
Atomic Radius INCREASES
Atomic Radius INCREASES
Why does the size of the element
increase going down?
Electron Shells
 Each
period on the periodic table represents a
different electron shell.
The more down you go, the more shells there are.
Therefore, the larger the atom’s size (RADIUS)
will be.
As you go down the periodic table, the atoms
get BIGGER
WHY DOES THE SIZE OF THE ELEMENT DECREASE
GOING ACROSS? FROM LEFT TO RIGHT?


Atomic radius explained…
Going from left to right on the periodic table, the
atomic number increases and the _________
Positive
charge on the nucleus increases. Therefore,
Attraction between the _____
e- and Positive
the __________
________
increases, causing the radius to
nucleus
Decrease
_____________.
As you go across the periodic table, the atoms get
SMALLER because….?
A. The Electronic Nature of Chemical Bonding
Electrostatic Force: Is a force existing as a result of the attraction
or repulsion between 2 charged particles



+ and – ATTRACT (different charges)
+ and + REPEL
– and – REPEL
The closer the charges are, the greater the force
The greater the charge, the greater the force
Na +1 and Cl 1Greater Force
Mg 2+ and Br 1-
ELECTRON SHELLS
OPEN SHELL: is a shell containing less than its
maximum number of electrons.
O :1s2 2s2 2p4
2 e-
CLOSED SHELL: is a shell containing its maximum
number of electrons.
Ex: noble gases
Ar18 : 1S2 2S2 2P6 3S2 3P6
Valence Electrons: Total number of electrons in open
shells that can participate in a chemical bond.

Use the periodic table to determine the number
of valence electrons (for s and p orbitals)
Atom
K
Ca
Ga
Ge
As
Se
Br
Kr
Group
I
2
3
4
5
6
7
8
# of
valence e(e in
outter
shells)
1 e- 2 e- 3 e- 4 e- 5 e- 6 e- 7 e- 8 eTechnically none are involved in
bonding so not really valence
electrons
CHLORINE AS AN EXAMPLE
Draw the valence electrons for Chlorine.
Chlorine is in group 7
So…..7 Valence e-
Add electrons one at
a time in a clockwise
fashion.
Cl
One unpaired
bonding e-.
Lone Pairs…not involved in bonding
VIII.3 CHEMICAL BONDING
Valence: The number of unpaired valence electrons on
the atom (COMBINING CAPACITY)
each ORBITAL holds 2 eonly dealing with s and p orbitals so the
maximum number of electrons in a shell is:
2 _______________
e- (s) + 6 e- (p) = 8 e only UNPAIRED electrons take part in
bonding!
B
Group 3…3 e-
F
Group 7…7 e-
VIII.3 CHEMICAL BONDING
Going across periodic table the valence of an atom:
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 8
1
2
3
4
3
2
1
0
+1
+2
+3
+4
-3
The valence is the combining capacity! 
-2
-1
0
A few more things to know…
Ionization Energy (IE)
The minimum energy required to remove an electron
from a an atom or molecule in the gaseous state.
Ca + energy → Ca2+ + 2e-
Neutral
Ionization
Energy
IONIZATION ENERGY
Going ACROSS the periodic table the ionization energy
(IE) increases Ionization Energy
Why? The Electronegativity increases as you go across the periodic
table….thus the elements hold onto their electrons more strongly…..thus more
energy to pull them away.
Ionization Energy
Going DOWN the periodic table the IE decreases
Why?
More energy shells.
More energy shells (layers)…thus farther from nucleus
(Positively charged)…..thus there is less attraction the farther
away you go….so less energy to pull electrons away.
Ionization Energy
He has the GREATEST ionization energy
Fr has the LEAST ionization energy
HOMEWORK
Pgs 297 – 298
#’s: 1, 4, 5,6 7,11, 12