The Periodic Table

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The Periodic Table
Period the horizontal rows in the periodic
table.
- The period is equal to the outermost
principle
energy level containing electrons
- For periods 1 through 4 the period is equal
to the number of sublevels in that principle
energy level
Group the vertical columns in the periodic table
- Elements in a group exhibit similar chemical
and
physical properties
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The Blocks of the Periodic Table
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Periodic Trends
Atomic Radius The distance from the center of
the nucleus of an atom to the outer edge of
that atom
As you go to the left and down the periodic
table
the atomic radius tends to increase.
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Why does the atomic radius decrease if we are
adding another proton and electron
when we move to the right?
Think as the principle quantum energy level of
an
atom as an amount of space.
- As you move down the periodic table you add
more space and make the atomic radius larger
- As you move from the left to the right there
is the same energy level (amount of space) but w
e
add another proton and electron
- This makes more attraction between these
particles and smooches the atom
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Ionic Radius The distance from the center of
the nucleus of an ion to the outer edge of t
hat ion
- As you go to the right and down the periodic
table the ionic radius tends to increase.
- The parent atoms of positive ions are always
larger than the ion.
- Because an energy level is lost and the
protons have an even greater pull
on the electrons
- The parent atoms of negative ions are always
smaller than the ion because they gain
electrons
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Ionization Energy the amount of energy required
to
remove the outermost electron
- The higher the number the harder it is to
take
away an electron
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Electronegativity (Electron Affinity) The
attraction that an atom has for electrons.
- This is the reason that atoms form bonds
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Chemistry of a Group (Family)
The elements in the periodic table are divided
into groups 1 through 18. The elements in each
exhibit related chemical properties which are
associated with the number of valence electrons
In groups 1, 2, and 13 through 18, as the atomic
number increases
a. The radius of the atom increases.
b. The ionization energy of the element
generally decreases.
c. Electronegativity of the element generally
decreases

• The elements tend to have more metallic
• properties

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Groups 1 and 2
A. elements in group 1 are called the alkali
metals
-except hydrogen
B. elements in group 2 are called alkaline earth
metals

• because of their high reactivity, groups 1 and
  2 occur
  
• in nature only as compounds

D. relatively low ionization energies and
electronagativities

• reactivity generally increases with an increase
  in
  
• atomic number

F. In the same period, each group 1 metal is
more reactive than the corresponding group 2 me
tal
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Groups 15 and 16
A. nitrogen is relatively inactive at room
temperature
B. nitrogen compounds are essential to all
living matter
C. generally nitrogen compounds are relatively
unstable
D. phosphorus is more reactive than nitrogen at
room
temperature
E. oxygen is an active nonmetal (reacts often
and easily)
F. sulfur is less reactive than oxygen
G. selenium and tellurium are rare elements
H. polonium is a radioactive element. Its is an
alpha emitter. It is the degradation product of
uranium.
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Groups 17
A. known as the halogen family
B. relatively high electronegativity of the
elements. Can only have negative oxidation stat
es.
C. fluorine has the highest electronegativity of
the elements. It can only have an oxidation sta
te of
-1
D. at room temperature fluorine and chlorine are
gasses, bromine is a liquid, and iodine is a sol
id
E. because of their high reactivity, the
halogens occur
in nature only in compounds
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Group 18
A. monatomic gases
B. complete outer shells which results in a
stable
electron configuration
C. also called inert gases or noble gases
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Chemistry of a Period
For nontransition elements in a period, from left
to right certain generalizations have been di
scovered
In each period as the atomic number increases
a. the radius of the atom generally decreases.
b. the ionization energy of the element
generally
increases.
c. the electronegativity of the element
generally increases.
d. the elements change from very active metals
to less active metals to very active nonmetals a
nd finally,
to inert gas
e. there is a transition from positive to
negative oxidation
states
f. the metallic characteristics decrease