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TRANSCRIPT
Periodic
Trends
So how is it arranged?
The elements are placed in specific places based on the way they look and act
The Periodic Table is organized by rows and columns
Rows (left to right)
Columns (up and down)
You've got your periods...
All of the rows go left to
right.
Each of the rows is
considered to be a
different period
Elements in the same
row have the same
number of electron
rings
And you got your groups…
When a column goes from top to bottom, it's called a group.
Elements in the same group have similar chemical properties
Elements in the same group have the same number of valence electrons
Trends
Atomic Radius
Ionization Energy
Electron Affinity/Electronegativity
Reactivity
Metallic Character
Atomic Radius
Size of the atom
Distance from nucleus to the outermost
electron energy level
Decreases from left to right
As you go from left to right, e- are put into
the same energy level, but there are more p+
Increases from top to bottom
As you go down, e- are filled into orbitals
(energy levels) that are farther away from
the nucleus
Atomic Radius
“Effective Nuclear Charge”
Amount of attractive “hold” or Force the
nucleus exerts on electrons
Net positive charge experienced by an electron
Positive Protons attract negative electrons inward
Inner electron energy levels “shield” the outer
electrons
Increases as you move along a period, left
to right
Decreases as you move down a group
Ionization Energy
Energy needed to remove the outermost e-
Elements with a high ionization energy will
not give up their electrons easily
Decreases from top to bottom
As you go down, atomic size is increasing,
therefore there is less attraction and it is easier to
remove an e-
Increases from left to right
As you go from left to right, atomic size is
decreasing, so it is more difficult to remove an e-
Ionization Energy
How do electron configurations explain
why there is a big change in energy at
the red line?
Electron Affinity /
Electronegativity
How good an atom is at pulling in an electron
Increases from left to right
As you go from left to right, atomic size is
decreasing, so the electrons are more
attracted to the nucleus
Decreases from top to bottom (generally)
As you go down, atomic size is increasing,
so there is less attraction of electrons to the
nucleus
Electron Affinity /
Electronegativity
Reactivity
Tendency of an atom to react
Metals – lose e- when they react
Reactivity is based on lowest Ionization Energy
Low ionization energy = high reactivity
Nonmetals – gain e- when they react
Reactivity is based on high electronegativity
High electronegativity = high reactivity
Metallic Character
Increases from top to bottom
Metallic character increases because
ionization energy decreases
Decreases from left to right
Metallic character decreases because
ionization energy decreases
Summary of Periodic
Trends