Transcript Ppt

Periodic Trends
The periodic table revisited
Trends in the Periodic Table
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Atomic Size
Ionization Energy
Ionic Size
Electronegativity
Atomic Size
• As you move down a group, the atomic
size increases
• The shielding of the nucleus by the
electrons is greater
• The introduction of the next energy
level
Atomic Size
• As you move across a period, the atomic
size decreases
• The energy level is the same
–The shielding is constant
Ionization Energy
• When an atom loses or gains an electron it
is an ion
• As you move down a group, the
ionization energy decreases
• As you move across a period, the
ionization energy increases
Ionic size
• As you move down a group, the ionic size
increases
• As you move across a period, the ionic
size decreases for cations, increases for
anions
Electronegativity
• Electronegativity is the tendency of an
atom to attract electrons when they are
chemically combined with another element
• Fluorine is the most electronegative
• As you move away from Fluorine in
any direction, the electronegativity
decreases