Download Honors Chemistry Chapter 6 Student Notes

Honors Chemistry
Chapter 6 Notes – The Periodic Table
(Student’s edition)
Chapter 6problem set:
24, 25, 28, 35, 37, 40-42, 46, 48, 55, 57, 62, 68
Useful diagrams:
Every single diagram/photograph/drawing has something that you can
learn from in this chapter. You should be familiar with any and all figures if you wish to
understand this chapter as fully as possible.
6.1 and 6.2
Organizing the Elements and Classifying the Elements
Origin of the periodic table
Johann Dobereiner (German) 1780 – 1849 and John Newlands (English) 1837 - 1898
both noted
Luther Meyer (German) - noted there is a strong pattern, but.......
Dimitri Mendeleev - publish
in 1869
- based on
- listed elements in order of
- left spaces for
Property
Eka - Aluminum
Ga (1875)
Atomic Mass
Density
Melting Point
Oxide Formula
68
5.9
low
E2O3
69.7
5.9
29.8 Co
Ga2O3
-
also predicted Eka - Silicon - Germanium
Mendeleev formulated the original Periodic Law -
In 1911, Mosely (English) discovers the
new Periodic Law -
so....
- History lesson - After his brilliant discovery, Mosely was drafted into the
infantry to fight for the crown in WW I. He was killed. Only after the war
was it realized that scientists should probably not be drafted into combat
roles. That policy exists to this day.
Reading the periodic table:
Periods:
-
on the periodic table
-
elements in the same period have the
-
elements in the same period
-
also known as
Groups:
-
on the periodic table
-
elements in the same group have the
-
elements in the same group
-
also known as
Why do elements in the same column have similar properties?
-
Periods of elements
Row #1 
elements 
electrons in shell #1
Row #2 
elements 
electrons in shell #2
Row #3 
elements 
Row #4 
elements 
electrons in shell #3
electrons in shell #4
Groups of elements and their Properties
Group 1 - Alkali Metals
-
-
-
“alkali” comes from Arabic - means “ashes” - early chemists separated
sodium and potassium compounds from ashes - the hydroxides of these
compounds are strongly basic.
These compounds are not found alone in nature - why? explosive with
water - they are stored under kerosene - very reactive.
They react with nonmetals to form salts.
Many of the compounds they form are white in color.
They are silvery, shiny (luster), have a low melting point, conduct
electricity, and are soft (so soft, you can cut them with a knife). They are
malleable (able to flattened into a sheet) and ductile (able to be drawn into
a wire).
Sodium and Potassium are particularly important in body chemistry.
Group 2 - Alkaline Earth Metals
-
-
“earth” - chemists term for oxides of these elements - it was originally
thought that the oxides of these elements were actually the elements
themselves.
Tend to form white colored compounds.
Strongly basic - 2nd most reactive elements.
Also not “lone state” elements.
Harder, denser than group 1.
Common in sea salts.
Transition Metals
-
Groups 3-12
Harder, more brittle, higher melting point than groups 1 and 2.
Form colored compounds.
Conduct heat and electricity well and are shiny.
Pd, Pt, Au - very unreactive (Noble metals).
Metalloids
-
B, Si, As, Te, At, Ge, Sb
Stairs and 2 people under the stairs.
Properties of metals and nonmetals.
Brittle - used in semiconductors, computers.
Halogens
-
Group 17
Most reactive of the nonmetals.
Not found free in nature.
“Halogen” - Greek for salt former.
Solids, liquids, and gases in this group.
Widespread – found in sea salts, minerals, living tissue.
Many applications - bleach, photography, plastics, insecticides.
Noble Gases
-
Group 18
Used to be called inert - not so since Kr, Xe, Rn made compounds.
Used to be called rare (He and Ar fairly abundant).
Least reactive elements
Used in air conditioners, double pane windows, lights, balloons.
Lanthanides
-
f block
Also known as the rare earth elements - not really rare.
They are shiny, silver, and reactive.
Used to make TV’s glow and in creating metal alloys
Actinides
-
f block
Unstable and radioactive.
All but 4 are artificially created.
Uranium used as nuclear fuel and for coloring glass and ceramics (fiesta
ware).
Also have found use in deep sea diving suits and smoke alarms.
f block elements are called inner transition elements - they were put into
their current position by Glenn Seaborg - the only living person ever to
have an element named after himself.
6.3
Periodic Trends
Periodicity in properties
Coulombic Attraction - properties are related to the attraction of a
for
electrons - depends on
nucleus
.
2 properties that depend on coulombic attraction -
.
2 properties that are based more on # of electrons -
.
Atomic Radius:
basic idea is “how an atom is” - atoms are not spheres with outer boundaries
due to the wave mechanical model.
covalent atomic radius - distance from the
involved in a covalent bond.
+
+
between two atoms when they aren’t
Van der Waals radius bonded together.
+
+
atomic radius of metals -
+
when it’s
to the
between the nuclei of two metal atoms.
+
atomic radius is measured in
Van der Waals radius is generally greater than
Metallic radius is also generally greater than
.
.
. Why? -
.
Predictions (2 trends):
↓ p-table = size
- natural, logical - add more
 p-table = size
- not logical! why?
From left to right .
trend looks like …
graph looks like …
Electronegativity and Periodicity:
Electronegativity- basic idea - the ability of an atom to
electrons (Linus Pauling)
Decreased distance from the nucleus =
Electronegativity is related to atomic size:
trend looks like...
↓
size =
electronegativity
trend looks like.....
graph looks like...
Real definition of electronegativity - the ability of an atom to
are shared with another atom in a
.
electrons that
Electronegativity values are based on Pauling’s work with bond energies.
Ionization Energy and Periodicity:
ionization energy - energy required to
the most loosely held electron from
the
energy level of an atom in its gas phase.
A(g)
+
energy

A+ (g) +
e-
As the distance between the protons and the outer shell electrons decreases, the
protons’ hold on the electrons
. Increase hold on the electrons means
that
energy is required to
the electrons.
trend looks like …
graph looks like...
IE is related to atomic radius - 2 reasons why smaller going down the table
1. greater distance from the nucleus 2. kernel electrons “
” outer electrons from the nucleus
There is also a 2nd and 3rd IE – always
IE of elements greatly
attraction
than the first.
when the outer shell has been emptied.
Which has a higher 2nd IE - Na or Mg?
Which has a higher 3rd IE - Al or Mg?
Position of Electrons:
IE and Electronegativity are related, but different.
IE involves the attraction of a nucleus for an
. IE can be
.
Thus, increase attraction equals increase energy required to take the electron.
Electronegativity is not a measurement of
- it can’t be directly studied. It is
determined mathematically by equations based on
values (Pauling)
NIB – Valence Electrons:
Valence electrons -
involved with bonding
Column # =
1
8
2
3
4
5
6
7
Usually 2
NIB - Electron Affinity:
Electron Affinity - energy change when an electron is
atom.
A
+
e-
+
-
A-

+
energy
(
by a neutral
, negative delta H, high EA)
small atom
some atoms must be forced to accept an electron
A
e
+
energy

A- (
, positive delta H, low EA)
large atom
Basic idea - some atoms want to
electrons - they have a high electron
affinity value - they
a lot of energy when accepting electrons
examples:
F = -322 kJ/mole
Na = -53 kJ/mole
F has a higher electron affinity =
value
general trend looks like …
but......
Column #
S
p
Energy
1
2
3
4
5
6
7
8
graph looks like this....
Also - 2nd EA values are always positive
Groups 6 and 5 become negative ions after the 1st EA. So, trying to place a 2nd electron
into a
encounters significant repulsion; therefore,
.
An example is Fluorine - fluorine
energy when taking an electron,
but it only wants one electron. If it takes 2 electrons it has
electrons
than it needs and becomes like sodium. The 2nd EA is
as you
need
it to take a 2nd electron. F-1 has a negative charge and thus
repels the new electron.
NIB - Activity
For metals - larger atoms are
For nonmetals - smaller
active - why? -
active - why? -
metal activity trend
nonmetal activity trend
Most active metals + most active nonmetals = most
ex: RbF -
stable
LiBr -
compounds
stable
NIB – Metallic Character:
Metallic character - some metals are said to be more metallic than others really it is just a statement about their activity. If they are
active, they
are said to be more
.
trend looks like this...
Ionic Radius
Ions are created by
electrons.
Cation Anion Metals tend to become
Nonmetals tend to become
.
.
Cations are smaller than the neutral atom - why? -
Anions are larger - why? trend looks like this....
Na
Na+1
examples:
Li or Li+1 O or O-2 Li+1 or Be+2 O-2 or N -3 -
is smaller because it
(the protons have a
coulombic attraction for the electrons
is bigger because the protons
pull as much on the
additional electrons (coulombic attraction goes
)
is bigger because
is bigger because
protons pull the shell in
protons pull the shell in
NIB - Isoelectronic Species
Kinds of atoms that have the same electron configuration.
examples - Ne 1s2 2s2 2p6
so is
All of the atoms above are considered to be
In general - an isoelectronic series decreases in radius as atomic number
.
.