Transcript The Periodic Table and Periodic Law

The Periodic Table
Trends
Chapter 6
Section 6.3: Periodic Trends
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The electron cloud surrounding the
nucleus is based on the probability and
does not have a clearly defined edge
Atomic size is defined by how closely an
atoms lies to a neighboring atom
Atomic Radii Trend
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Trends within
periods
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Generally decreases
as you move left-toright across a period
(row)
Trends within
groups
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Generally increases
as you move down a
group
Ionic Radius
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An ion is an atom or a bonded group of
atoms that has a positive or negative
charge
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When atoms lose electrons and form
positively charged ions, they always become
smaller
When atoms gain electrons and form
negatively charged ions, they always become
larger
Lose Electrons  Smaller ionic radii
Gain Electrons  larger ionic radii
Ionization Energy (I.E.)
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Ionization Energy- the energy required to
remove an electron from a gaseous atom
1st Ionization Energy- removes the 1st
electron
2nd Ionization Energy- removes the 2nd
electron… and so forth
I.E. is an indication on how strongly an
atom’s nucleus holds onto its valence
electrons
Octet Rule- atoms tend to
gain, lose or share
electrons in order to
acquire a full set of eight
valence electrons
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Octet Rule- atoms tend to gain, lose or share
electrons in order to acquire a full set of eight
valence electrons
 Hydrogen and Helium are exceptions (they’ll be
happy with 2 V.E.)
 Determines the types of ions likely to form
 Elements on the right side tend to gain
electrons
 Elements on the left side tend to lose
electrons
Electronegativity
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Indicates the relative ability of its atoms to
attract electrons in a chemical bond
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Noble gases form very few compounds so
they are left out
In a chemical bond, the atom with the greater
electronegativity more strongly attracts the
bond’s electrons
Atomic radius increases
Ionization energy decreases
Electronegativity decreases
In Summary
Atomic radius decreases
Ionization energy increases
Electronegativity increases
1A
0
2A
3A 4A 5A 6A 7A