The Periodic Table
Unit 3
Overview
• Discovery of table
• Introduction to table
▫ States of matter,
radioactivity, synthetics
• Metals, nonmetals, metalloids
▫ Location and properties
• Periods versus groups
• Group Location and Properties
▫ Alkali metals, alkaline earth
metals, transition metals,
halogens, noble gases, rare
earth elements
• Periodic Trends
▫
▫
▫
▫
▫
Effective nuclear charge
Atomic radius
Ionization energy
Electron affinity
Electronegativity
• Ionic Radii
Discovery of the
Elements
Early Element Tables (1778-1808)
Dmitri Mendeleev’s
Periodic Table
• 1869
Other tables
following Mendeleev
Henry Moseley (1887-1915)
• Periodic Law (atomic numbers)
Modern Periodic Table
117 Known Elements
• 83 are stable and found in nature.
▫ Many of these a very rare.
• 7 are found in nature but are radioactive.
• 27+ are not natural on the earth.
▫ 2 or 3 of these might be found in stars.
Why do we have the
rows at the bottom?
This arrangement takes too
much space and is hard to read.
Radioactive Elements
• Radioactive elements
▫ Elements with an unstable nucleus
▫ Spontaneously give off radiation and/or
subatomic particles as nucleus “breaks apart”
▫ Can occur naturally be man-made
• Used in various forms of technology
▫ Medicine, food preservation, weaponry, etc.
Man-made (Synthetic) Elements
• Do not occur naturally on Earth
▫ Artificially created
• Unstable and decaying with half-lives between
years and milliseconds
• Made by bombarding any known element with a
form of proton species such as helium ions or
the use of proton bombardment via the use of a
cyclotron to accelerate both of these types into
another element to create other more heavy
elements
Why make elements that last such a
short time?
• To support theories of the nature of matter.
▫ The standard model of the nature of matter predicts
that elements with roughly 184 neutrons and 114
protons would be fairly stable.
▫ 288115, which lasted a relatively long time, has 115
protons and 173 neutrons.
• The technology developed to make new elements is
also being used for medical purposes.
▫ Heavy-ion therapy as a treatment for inoperable
cancers
▫ Beams of carbon atoms shot at tumor.
States of Matter (Room Temperature)
Solid
H
Liquid
Li Be
Gas
Na Mg
K Ca Sc Ti
Rb Sr
Y
V
Fr Ra Lr
B
C
N
O
F
Ne
Al
Si
P
S
Cl Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba *Lu Hf Ta W Re Os Ir
+
He
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
*
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
+
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No
Metals
H
He
Li Be
B
C
N
O
F
Na Mg
Al
Si
P
S
Cl Ar
K Ca Sc Ti
Rb Sr
Y
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba *
Lu Hf Ta W Re Os Ir
+
Fr Ra Lr
Ne
* La Ce
+ Ac
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No
Properties of Metals
• Have a shiny metallic luster
• Conduct heat well and conduct electric currents
in the solid form
• Malleable
▫ For example, gold, Au, can be hammered into very
thin sheets without breaking.
• Ductile
▫ Can be stretched into wiring without breaking
• Solid at room temperature (except mercury, Hg)
Nonmetals
H
He
Li Be
B
C
N
O
F
Na Mg
Al
Si
P
S
Cl Ar
K Ca Sc Ti
Rb Sr
Y
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba *Ly Hf Ta W Re Os Ir
+
Fr Ra Lr
Ne
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
* La Ce
Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
+ Ac Th
Pa U Np Pu Am Cm Bk Cf Es Fm Md No
Properties of Nonmetals
• Dull
• Poor conductors of heat and electricity
• Brittle in the solid form
▫ For example, if you hit a piece of sulfur, S, with a
hammer it will shatter instead of flattening out
• Not ductile
▫ Cannot be stretched into wiring
• Exist as solids, liquids, and gases at room
temperature
Metalloids
H
He
Li Be
B
C
N
O
F
Na Mg
Al
Si
P
S
Cl Ar
K Ca Sc Ti
Rb Sr
Y
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba *Lu Hf Ta W Re Os Ir
+
Fr Ra Lr
Ne
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
*
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
+
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No
Properties of Metalloids
• Mixed properties of metals and nonmetals
• Shiny or dull
• More conductive than nonmetals but less than
metals
• Solid at room temperature
Periods
Periods are
assigned numbers
1
H
2
Li Be
B
C
N
O
F
3
Na Mg
Al
Si
P
S
Cl Ar
4
K Ca Sc Ti
5
Rb Sr
6
Cs Ba Lu Hf Ta W Re Os Ir
7
Fr Ra Lr
He
Y
V
Ne
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No
A group or family
IA
II A
III A IV A V A VI A VIIA 0
Groups are assigned
Roman numerals
with an A or B
H
Li Be
Na Mg III B IVB V B VIB VIIB
K Ca Sc Ti
Rb Sr
Y
V
VIII
IB IIB
B
C
N
O
F
Ne
Al
Si
P
S
Cl Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba Lu Hf Ta W Re Os Ir
Fr Ra Lr
He
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No
Group Numbers
Groups
Alkali metals
Alkaline earth metals
IA
II A
H
He
Noble gases
Transition Metals
Li Be
Na Mg III B IVB V B VIB VIIB
K Ca Sc Ti
Rb Sr
III A IV A V A VI A VIIA 0
Halogens
Y
V
VIII B
C
N
O
F
Ne
Al
Si
P
S
Cl Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba Lu Hf Ta W Re Os Ir
Fr Ra Lr
IB IIB
B
I
Xe
Pt Au Hg Tl Pb Bi Po At Rn
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
Ac Th Pa U Np Pu AmCm Bk Cf Es Fm Md No
(
)
Rare Earth
Elements
Groups
• Elements in the same group have similar
properties
▫ Due to valence electrons being the same for each
element in the group
Alkali Metals (Group 1)
•
•
•
•
Most reactive metals
Never found free in nature
React explosively with water
Extremely soft (can be cut with knife)
Alkaline Earth Metals (Group 2)
•
•
•
•
•
Less reactive than metals
Not found free in nature
Slightly react with water
Soft but not as soft as alkali metals
Often used in fireworks
Transition Metals (Groups 3-12)
•
•
•
•
Great conductors of heat/electricity
Hard metals
High melting/boiling points
Malleable and ductile
Halogens (Group 17)
• Most reactive nonmetals
• Elements exist as all three solid, liquid,
and gas
• Elements in pure form are diatomic (F2,
Cl2, Br2, I2)
Noble Gases (Group 18)
• Nonreactive (except for a few recently found
compounds)
• Usually only exist in free state in nature
▫ Most are found in atmosphere in trace amounts)
• All gases at room temperature
• Colorless and odorless
Rare Earth Elements
(Lanthanides/Actinides)
•
•
•
•
Usually silver, silvery-white, or gray metals
High luster but tarnish readily in air
Highly conductive
Many have similar or the same properties so difficult to
distinguish one from the other
• Occur naturally in minerals
• Not particularly rare but prior to 1945 it was a long,
tedious process to obtain pure samples of the elements
Effective Nuclear Charge
• Many properties of atoms are due to the average distance of the
outer electrons from the nucleus and to the effective nuclear
charge, Zeff, experienced by these electrons.
▫ Electrons are simultaneously attracted to nucleus and repelled by
the other electrons.
▫ Can estimate net attraction of each electron to nucleus by
considering its interaction with average environment created by
nucleus and other electrons
• Inner electrons “shield” valence electrons from attraction of nucleus
▫ Electrons in the same shell do not screen each other effectively
Effective Nuclear Charge
• Interaction of charges:
Zeff = Z – S
• Zeff = effective nuclear charge
• Z = number of protons in the nucleus
• S = Shielding effect from other electrons
• Zeff increases moving left to right across a period
• Zeff stays the same moving down a group
Atomic Radius
• Half of the distance between nuclei in covalently
bonded diatomic molecule
▫ Radius decreases across a period
 Increased effective nuclear charge due to decreased
shielding
▫ Radius increases down a group
 Each row on the periodic table adds a “shell” or
energy level to the atom
Atomic
Radius
Ionization Energy
• The energy required to remove an electron from an atom
▫ Increases for successive electrons taken from the same atom due
to the increased effective nuclear charge
• The first ionization energy of an atom is the minimum energy
needed to remove an electron from an atom
• The second ionization energy is the energy needed to remove a
second electron,
• The third is to remove the third electron and so forth…
Ionization Energy
• Tends to increase across a period
▫ Electrons in the same quantum level do not shield as effectively
as electrons in inner levels
▫ Irregularities at half filled and filled sublevels due to extra
repulsion of electrons paired in orbitals, making them easier to
remove
• Tends to decrease down a group
▫ Outer electrons are farther from the nucleus and easier to remove
Trends in first
ionization energy
Electron Affinity
• The energy change associated with the addition of an
electron
• Affinity tends to increase across a period
• Affinity tends to decrease as you go down in a period
▫ Electrons farther from the nucleus experience less
nuclear attraction
▫ Some irregularities due to repulsive forces in the
relatively small p orbitals
Electron Affinity
Electronegativity
• A measure of the ability of an atom in a chemical
compound to attract electrons
• Electronegativity tends to increase across a period
▫ As radius decreases, electrons get closer to the
bonding atom’s nucleus
• Electronegativity tends to decrease down a group or
remain the same
▫ As radius increases, electrons are farther from the
bonding atom’s nucleus
Electronegativity
Summary of
Periodic Trends
Ionic Radii
• Cations
▫ Positively charged ions form when an element
loses an electron
▫ Cation is smaller than corresponding atom
• Anions
▫ Negatively charged ions form when an element
gains an electron
▫ Anion is larger than corresponding atom