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THE PERIODIC
TABLE
When something occurs at regular
intervals(you can predict what happens / comes next)
PERIODIC
So what makes the periodic table periodic?
ATOMIC NUMBER!!!
(across the chart)
The properties of the elements are a
periodic function of their atomic numbers
PERIODIC LAW
.
All of the elements in a horizontal
row
PERIOD
All of the elements in a vertical
column(aka Family)
GROUP
Dmitri Mendeleev (1834-1907)
invented the periodic table based on
increasing atomic mass…and yes, he too, is your friend
Henry Moseley (1913)
revised the periodic table based on
properties and atomic number
…and yes, he too, is your friend
s1 groupALKALI METALS
• Good Conductors
s2 group
ALKALINE EARTH METALS
• Harder, more dense, stronger than alkali
d sub energy level
TRANSITION METALS
• Columns 3-12
4f sub energy level
LANTHANOID SERIES
• Z = 57-70
5f sub energy level
ACTINOID SERIES
• Z = 89-102• All have radioactive forms (unstable p+ & N°)
Columns 13, 14, 15, 16 are
named by the first element in the
column(e.g. Boron Group)
p5 groupHALOGENS
• Combine with metals to form salts
• Very reactive
p6 groupNOBLE GASES
• Inert gases (not reactive)• 8 valence electrons
Classifications by e- Configuration
• Noble Gases: p6
• Representative Elements: s or p (not p6)
• Transition Metals: “d-block”
• Inner Transition Metals: “f-block”
Stability of e-
configurations
The eight outer electrons in an
atom
OCTET
FACT:Atoms with full outer energy levels are very stable (less reactive)
If an atom has 8 electrons in its outer
energy level, it is unreactive (save He)
OCTET RULE
Pretend we had a sub-energy level with 8 electrons. When would it be most
stable?(The egg carton example)
FACT #2:Atoms with filled,
half filled, or empty sub-energy levels are slightly more stable
Check out PT on pages 392-393.
Look at Cu. What is the e- configuration?
[Ar] 4s13d10…why???
The atom is more stable if it has a full “d” sub-energy level and a ½ full “s” sub-
energy level
Check out the PT on page 392-393.
Look at Gd. What is the e- configuration?
[Xe] 6s24f75d1…why???
To Review…How do we make sub energy levels more stable?
Move electrons so SUB-ENERGY levels are FULL,
HALF FULL, or COMPLETELY EMPTY
Now…how do we make ENERGY LEVELS more
stable?
Ways to make full outer energy levels:
•Add electrons to a partially filled outer energy level•Lose all electrons in the outer energy level•Share electrons with another atom
Periodic Trends
ATOMIC RADIUS
The distance from the center of the nucleus
to the outermost energy level
The atomic radius INCREASES
within a family
(just adding energy levels)
The atomic radius DECREASES
within a period
(more positive charge pulling e-)
SHIELDING EFFECT
The positive pull is less because the distance between nucleus and electrons is greater
IONIZATION ENERGY
the energy required to remove an electron
from an atom
The ionization energy DECREASES as you
go down a family
(shielding effect)
The ionization energy
INCREASES across a period
(more p+ have more pull on e-)
ELECTRON AFFINITY
how much an atom desires another
electron
The electron affinity DECREASES as you
go down a family
(shielding effect)
The electron affinity INCREASES across a period
(except for the noble gases)
(more p+ have more pull on e-)
ELECTRONEGATIVITY
The tendency of an atom to attract electrons to
itself when it is bonded to another atom
The electronegativity DECREASES as you
go down a family
(shielding effect)
The electronegativity INCREASES across a
period
(more p+ have more pull on e-)