Periodic Trends Download

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Periodic Trends
Property
Atomic Radius
(size)
First Ionization
Energy (IE 1)
Increasing
Trend (in
magnitude)
Rationale
Half the distance between
the nuclei of two atoms of
the same element bonded
together

L to R: Additional e– are added to same shell of electrons, additional protons draw the entire
shell in, making the atoms smaller

Top to Bottom: Additional e– are added to shells of electrons further out, which do not feel
the entire charge of the additional protons in the nucleus (shielding by inner e–)
The energy required to
remove the outermost e–
from a neutral gaseous
atom

Definition

The energy change that
occurs when an e– is
Electron Affinity accepted into a neutral
atom (usually energy is
released, (−) sign)

A measure of the ability of
an atom to attract electrons
Electronegativity
in a compound (4.0 is the
(En)
max. En value on the
Pauling scale)



Opposite of trend in atomic radius. The outermost e– in a larger atom is farther from the
nucleus and has more shielding from the inner e-, therefore it does not feel as much pull
from the nucleus and is easier to remove. Alternate explaination: The outermost e– in a
larger atom is in a higher energy level which is closer to n = ∞, therefore not as much
energy is required to promote this e– from its current energy level to n = ∞.
Opposite of trend in atomic radius. An electron will drop in to fill the innermost vacancy
available in an atoms electron energy levels. Because large atoms have their inner energy
levels already occupied by other electrons, the e- that is accepted can not drop in as far,
therefore less energy is released. Energy would be required to accept an e- that disrupts a
full shell electron configuration, therefore the e- is ejected from the atom again.
Opposite of trend in atomic radius. The valence e– (e– in the outermost occupied principle
energy level) are responsible for the chemical properties of an atom. It is these valence e–
that are gained, lost, or shared in the chemical reactions that form compounds. In a larger
atom the valence e– are farther from the nucleus and have more shielding from the inner e–,
therefore they do not feel as much pull from the nucleus and are not as strongly attracted.
A. Romero 2008