Electrons and
Periodic Behavior
Cartoon courtesy of NearingZero.net
Orbital filling table
Electron configuration of
the elements of the first
three series
Chemical Symbols
Antimony
Water
Copper
Sulfur
Sulfuric acid
Symbols used in the 18th Century
Oxygen
Nitrogen
Copper
Hydrogen
Sulfur
Mercury
Carbon
Silver
Water
S
Carbon dioxide
Lead
C
Potassa
L
Alcohol
Symbols used by John Dalton
Brownlee, Fuller, Hancock, Sohon, Whitsit, First Principles of Chemistry, 1931, page 74
Soda
Gold
G
Mendeleev’s Periodic Table
Dmitri Mendeleev
Modern Russian Table
Greek Elements
A Spiral Periodic
Table
“Mayan”
Periodic
Table
Alchemy !!
Period
or Family
TheGroup
Periodic
Table
Group or
family
Period
The Properties of a
Group:
the Alkali Metals
Easily lose valence electron
(Reducing agents)
React violently with water
Large hydration energy
React with halogens to form
salts
Potassium Metal in
Water
Newmark, CHEMISTRY, 1993, page 25
Groups/Families on the
Periodic Table
 Noble Gases: Family18
 Alkali Metals: Family 1
in pure state they all have a silvery
appearance and are soft enough to cut
with a knife
Extremely reactive so aren’t found as
free elements
Noble Gases
Groups/Families on the
Periodic Table
 Alkaline-earth metals: Group 2
harder, denser, and stronger than group
1 or alkali metals
Have higher melting points than group
1, and are less reactive (although still
reactive enough not to be found as free
elements)
Halogens: Group 17
Most reactive nonmetals
Carbon….The
Essence of Life
Special elements
 Hydrogen and Helium are special b/c although
they share some characteristics with their
groups/families, they are different b/c they have
properties that are not similar to those of ANY
group
 Hydrogen and helium are the simplest and
most abundant elements. Hydrogen makes up
76% of the mass of the universe and helium
makes up 23%
Life or Death Elements
Properties of Metals
 Metals are good
conductors of heat and
electricity
 Metals are malleable
 Metals are ductile
 Metals have high tensile
strength
 Metals have luster
Examples of Metals
Potassium, K
reacts with
water and
must be
stored in
kerosene
Copper, Cu, is a relatively soft
metal, and a very good electrical
conductor.
Zinc, Zn, is
more stable
than potassium
Mercury, Hg, is the only
metal that exists as a
liquid at room temperature
Properties of Nonmetals
Carbon, the graphite in “pencil lead” is a great
example of a nonmetallic element.
 Nonmetals are poor conductors of heat and
electricity
 Nonmetals tend to be brittle
 Many nonmetals are gases at room
temperature
Examples of Nonmetals
Sulfur, S, was
once known as
“brimstone”
Graphite is not the only
pure form of carbon, C.
Diamond is also carbon;
the color comes from
impurities caught within
the crystal structure
Microspheres
of phosphorus,
P, a reactive
nonmetal
Properties
of Metalloids
Metalloids straddle the
border between metals
and nonmetals on the
periodic table.
 They have properties of both metals and
nonmetals.
Metalloids are more brittle than metals, less
brittle than most nonmetallic solids
 Metalloids are semiconductors of electricity
 Some metalloids possess metallic luster
Silicon, Si – A Metalloid
 Silicon has metallic luster
 Silicon is brittle like a nonmetal
 Silicon is a semiconductor of
electricity
Other metalloids include:





Boron, B
Germanium, Ge
Arsenic, As
Antimony, Sb
Tellurium, Te
Aspirin
Determination of Atomic Radius:
Half of the distance between nuclei in
covalently bonded diatomic molecule
"covalent atomic radii"
Periodic Trends in Atomic Radius
Radius decreases across a period
Increased magnetic attraction
Radius increases down a group
Addition of principal quantum levels
Table of
Atomic
Radii
Ionization Energy - the energy
required to remove an electron
from an atom
Tends to increase across a period
Atoms become closer to a full electron octet
in the outer energy level
Tends to decrease down a group
Outer electrons are farther from the
nucleus
Table of 1st Ionization Energies
Ionization of Magnesium
Mg + 738 kJ  Mg+ + eMg+ + 1451 kJ  Mg2+ + eMg2+ + 7733 kJ  Mg3+ + e-
Another Way to Look at
Ionization Energy
Electronegativity
A measure of the ability of an atom in a chemical
compound to attract electrons
Electronegativities tend to increase across
a period (full octet)
Electronegativities tend to decrease down a
group or remain the same
Periodic Table of
Electronegativities
Summation of Periodic Trends