Transcript No Slide Title

Periodic Table
I.
Mendeleev
A.
Russian Chemist - In 1869 - organized elements according
to their properties
B.
Arranged elements according to their increasing atomic
mass - this but some of them out of order
1.
found a reoccurring pattern with in the elements
a.
Referred to pattern as periodic.
C.
left gaps for undiscovered elements - gave chemists an
insight to look for these elements
1.
elements with atomic masses of 44, 68,72,
and 100
2.
these elements where
a.
II
Scandium (1879), Gallium(1875),Germanium,
and Technetium respectively
Moseley ( 1887-1915)
A.
did work with x-ray determination of atomic numbers
B.
Led to arranging the elements by increasing
atomic number
III.
Periodic Law
A.
IV
The physical and chemical properties of the elements
are periodic functions of their atomic number
Modern Periodic Table (long form)
A.
Arranged by increasing atomic number
B.
Horizontal Rows known as series or periods
1.
Increase in atomic number by 1
2.
Lanthanide series and the actinide series last two rows at the bottom of the periodic
table
C.
Vertical rows known as groups or Families
1.
Group 1 -
Alkali metals - React with violently
with water. Not found alone in nature,
soft silvery metals. Also known as
the Sodium Family
Alkali Metals
Soft, silvery colored
metals
Very reactive!!!
Alkali Metals reacting with water:
•
•
•
•
•
Li (Lithium)
Na (Sodium)
K (Potassium)
Rb (Rubidium)
Cs (Cesium)
What would you
expect from
Francium?!?!
2.
Group 2 -
Alkaline earth metals - less
reactive then the alkali metals also known as the Calcium family
Alkaline Earth
Metals
Silvery-White Metals
Fairly reactive
Many are found in rocks
in the earth’s crust
3.
Group 17 -
Halogen family - bleaching
tendencies, very reactive
Halogens
Most are
Poisonous
Fairly reactive
Chlorine Gas was used as a
chemical weapon during World
War I.
It was used by the Nazis in
World War II.
4.
Group 18 -
inert or noble gas family - mostly
non-reactive
Noble Gases
Unreactive
Gases at room
temperature
Jellyfish lamps made with noble
gases artist- Eric Ehlenberger
Colors Noble Gases
produce in lamp tubes:
• Ne (Neon): orange-red
• Hg (Mercury): light blue
• Ar (Argon): pale lavender
• He (Helium): pale peach
• Kr (Krypton): pale silver
• Xe (Xenon): pale, deep blue
D.
Blocks
1
s block - first two columns
2.
p block - last 6 columns
p block
s block
3.
d block - also known as the transition elements
Transition Metals
Most are good
Conductors of
electricity
Malleable (easily
bent/hammered into
wires or sheets)
4.
f block - last two rows at the bottom
Lanthanide
Series
Actinide
Series
PERIODIC PROPERTIES
Atomic Radii
Ionization Energy
Electron Affinity
Ionic Radii
Electronegativity
V
Trends on the periodic table
A.
Atomic Radius - distance between the center of the
nucleus to the outer most electrons
1.
no real way to measure just the radius of atoms
a.
best method is to measure the distance
between two adjacent atoms
Atomic Radius
i.
2.
covalent radius - half the distance
between the nuclei of two identical atoms
ii.
ionic radius - half the distance between two
nucleus of ions held together by an ionic bond
iii.
metallic radius - half the distance between nuclei of
two atoms in contact in a crystal
Going down the Families - Atomic radius increases
a.
why - the increasing number of energy
levels make the atom larger - like adding
floors onto a hotel
i.
shielding affect - that is where the inner
electrons shields the outer electrons
from the nucleus
3.
Going across the periods from left to right atomic radius decreases
a.
why - the more protons in the nucleus draws
the electrons in tighter
Row (periods)
5+
B
2p 1
6+
C
2p2
7+
N
2p3
Atomic Radii
Remember - Electrons like to be held tight to the
nucleus
Nucleus
electron
B.
Ionization energy - energy required to remove the outer most
electrons
1.
going down a family - ionization energy decreases
( it easier to remove and electron from the elements at
the bottom)
a.
2.
why - electrons are farther away from the
nucleus and are held less strongly thus
allowing them to be removed with less
energy
Going across a period - from left to right - ionization energy
increases
a.
why - electrons are held tight to the nucleus
which makes it more difficult to remove
them
Ionization Energy
Mg 1s2 2s2 2p6 3s2
 1s2 2s2 2p6 3s1
Mg+
Mg(g) + 738kJ/mol  Mg+ + eWhen the Mg atom loses an electron it will have more protons than electrons and therefore
acquire a +1 charge. Known as an ion
N
   

7N
   

7
This is N+

1s
2
2s
2
2p
3
1s 2 2s 2 2p 2
Atomic radii in angstroms
Which element would be most easily ionized?
C.
Electron affinity- “love for electrons”
1.
Going across the periodic table from left to right electron affinity increases
a.
2.
why - electrons like to be held tight to the
nucleus. We already know that atoms on the
right side of the periodic table have a small
atomic radius and hold on to their electrons
tight
Going down the periodic table - electron affinity
decreases
a.
why - electrons are held less tightly due to
the size of the atom
The N atom gains an electron, it will have more electrons than
protons and there-fore acquire a negative charge
7N
7
N
   

     
This is N-

1s 2 2s 2 2p3

2
2
1s 2s 2p
4
Electron Affinity
Electron Affinity (kJ/mol)
Electron Affinities of Some Elements
1 2
0
-50
-100
-150
-200
-250
-300
-350
-400
3 4
5 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20
Ar
He
H
Ne
N
Be B
Mg
Na
Li
C
P
Ca
Al
K
S
O
Si
F
Atomic Number
Large negative numbers are favorable!
Cl
Electronegativity, 
 is a measure of the
ability of an atom in
a molecule to attract
electrons to itself.
Concept proposed by
Linus Pauling
1901-1994
D.
electronegativity - ability to attract a shared pair of electrons
1.
going down a family - electronegative decreases
a.
why - the size of the atom limits the ability of
an atom to hold on to its own electrons let alone
to attract another one
2.
going across the periodic table from left to right the electronegativity increases
a.
why - since the atom is smaller the positive charge of the
nucleus can break outside the atom and attract another
electron
E.
Reactivity
1.
There is a certain stability for an atom when there is
eight electrons in the outer shell (octet)
2.
since atoms on the left side of the period table want to
lose electrons - the ones on the bottom of the chart are
more reactive because they give up their electrons the
easiest
3.
since the atoms on the right side of the periodic
table want to gain electrons in order to obtain an octet
- the ones on the top are the most reactive
Reactivity
I
n
c
r
e
a
s
I
n
g
I
n
c
r
e
a
s
I
n
g
F.
ionic radius - the distance from the center of the
nucleus to the outer most energy level
1.
2.
ions - an atom or group of atoms with unequal
number of protons and electrons
a.
cations - positive ions - smaller than atom
due to greater number of protons than electron
b.
anions - negative ions - larger than there
atom due to a greater number of electrons
than protons
the elements on the left side of the periodic table
will form cations by losing an electron in order to
obtain an octet and therefore become smaller
3.
4.
the elements on the right side of the table will form anions by
gaining electrons and therefore become larger
removing a second electron becomes much more difficult
due to the increased attraction between the nucleus and
the electrons
Many anions
only stable
when in a
compound
G.
Metals on the left side of the periodic table
H.
Nonmetals are on the right
J.
transition metals are in the middle
For review
On page 156 2,8,9,10,17,18,24,26, 29,45,46