Transcript UNIT VIII - St John Brebeuf

UNIT VIII
The Periodic Table and Chemical Bonding
Lesson#3
VIII.2 THE PERIODIC TABLE

Organized according to ATOMIC # --- Mendeleev
Periodic Law: the properties of the elements
recur periodically when the elements are arranged
in increasing order by their atomic numbers
INCREASING REACTIVITY
A. The Modern Periodic Table
Trends in the Periodic Table:
PERIOD: is the set of all the elements in a given
row going ACROSS the table
FAMILY (group): is the set of all the elements in
a given column going down the table
VIII.2 THE PERIODIC TABLE
Metals, Nonmetals, and Semiconductors:

Metals:
 malleable (flatten into sheets)
 ductile
 opaque
 conduct electricity*
 solid at room temp (except....
 Lustre
)
*Metals conductivity decreases with an increase in
temp
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
VIII.2 THE PERIODIC TABLE
2. Elements become more metallic (or better
metals) going down a family in the periodic table
VIII.2 THE PERIODIC TABLE
3. The size of the elements radius decreases going
across a row and increases going down a family
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 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 _________
charge on the nucleus increases
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
ELECTRON SHELLS
OPEN SHELL: is a shell containing less than its
maximum number of electrons
CLOSED SHELL: is a shell containing its
maximum number of electrons
Ex: noble gases
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)
CHLORINE AS AN EXAMPLE
Draw the valence electrons for Chlorine.
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:
_______________
 only UNPAIRED electrons take part in
bonding!
ex:
B
F
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
The valence is the combining capacity! 
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-
IONIZATION ENERGY
Going ACROSS the periodic table the ionization energy
(IE) increases
Why?
Going DOWN the periodic table the IE decreases
Why?
Ionization Energy
He has the GREATEST ionization energy
Fr has the LEAST ionization energy
HOMEWORK

These are fast questions to answer, so solve them all
Hebden p. 164 # 35-39
Hebden p. 166 # 42-45 and p. 168 # 47
Hebden p. 168 # 48-51 and p. 170 # 53-56