Download Chapter 6 Notes

Honors Chemistry
Chapter 6 Notes – The Periodic Table
(Student 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 atomic masses related to
Luther Meyer (German) - noted there is a strong pattern, but.......
- publish first real periodic table in
- based on
- listed elements in order of
- left spaces for
Property
Eka - Aluminum
Atomic Mass
Density
Melting Point
Oxide Formula
68 amu
5.9 g/cm3
low
E2O3
-
Ga (1875)
amu
g/cm3
Co
also predicted Eka - Silicon -
Mendeleev formulated the original Periodic Law -
In 1911, Mosely (English) discovers the proton so....
new Periodic Law - Properties of elements are a periodic function of atomic
.
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.
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Reading the periodic table:
Periods:
Draw small period table below:
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 groups have the
elements in groups
also known as
Draw small period table below:
Why do elements in the same column have similar properties?
They have similar electron configuration - all members of the same group have the same # of:
General Drawing of the Periodic Table (metals, metalloids, nonmetals):
Specific Drawing of th e Periodic Table (groups, families, etc.):
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NIB - Groups of elements and their Properties – Students should refer to Appendix A!!!
Properties of families
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 the 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). Tell stereo story.
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 - 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 - rare earth elements - not really rare - shiny, silver, reactive, used
to make TV’s glow, used in creating metal alloys.
Actinides - f block - unstable, 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.
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6.3
Periodic Trends (Periodicity in properties)
Coulombic Attraction - properties are related to the attraction of a
nucleus for
electrons - depends on quantity of
and _______________________________.
2 properties that depend on coulombic attraction 2 properties that are based more on # of electrons -
Atomic Radius: basic idea is “how big an atom is” - atoms are not spheres with outer
boundaries due to the wave mechanical model.
covalent atomic radius - distance from the
when it’s involved in a covalent bond.
to the
between two atoms when they aren’t bonded together.
Van der Waals radius -
atomic radius of metals -
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 …
4
Electronegativity and Periodicity:
Electronegativity- basic idea - the ability of an atom to attract electrons (
)
Decreased distance from the nucleus = increase pull on an adjacent atom’s electron.
Electronegativity is related to
trend looks like...
:
trend looks like.....
Real definition of electronegativity - the
that are shared with another atom in a
graph looks like...
of an atom to
.
Electronegativity values are based on Pauling’s work with
.
Ionization Energy and Periodicity:
ionization energy - energy required to
the most loosely held electron
from the
energy level of an atom in its
.
A(g)
+
energy

A+ (g) +
e-
As the distance between the protons and the outer shell electrons decreases, the protons’ hold on
the electrons increases. Increased hold on the electrons means that more energy is required to
remove the electrons.
trend looks like …
graph looks like...
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IE is related to atomic radius - 2 reasons why smaller going down the table
1. greater distance from the nucleus - less attraction
2. kernel electrons “
” outer electrons from the nucleus
There is also a 2nd and 3rd IE - always higher than the first.
IE of elements greatly
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 electron. IE can be
.
Electronegativity is not a measurement of energy - it can’t be directly studied. It is
determined mathematically by equations based on bond energy values (
)
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 acquired by a neutral atom.
A
+
e-
A-

+
energy
(exothermic, negative delta H)
some atoms must be forced to accept an electron
A
+
e-
+
energy

A- (endothermic, positive delta H)
Basic idea - some atoms want to take on electrons - they have a high electron affinity
value - they release a lot of energy when accepting electrons
examples:
F =
kJ/mole
Na =
kJ/mole
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F has a higher electron affinity =
value
general trend looks like …
graph looks like this....
because......
Column #
S
p
Energy Value
1
2
3
4
5
6
7
8
Also - 2nd EA values are always positive
An example is Fluorine - fluorine
energy when taking an electron,
but it only wants one electron. If it takes 2 electrons it has more electrons than it needs and
becomes like sodium. The 2nd EA is
as you need to force it to take a 2nd electron.
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NIB - Activity
For metals - larger atoms are
active - why? -
For nonmetals - smaller
active - why? -
metal activity trend
nonmetal activity trend
Most active metals + most active nonmetals = most stable compounds
ex: RbF – very
LiBr –
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....
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examples:
Li or Li+1 Li+1 or Be+2 O or O-2 O-2 or N -3 NIB - Isoelectronic Species
Kinds of atoms that have the same
.
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
.
.
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