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AP Chemistry Periodic Trends Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Effective Nuclear Charge

 
Z 
effective
< Z 
actual
b/c Z 
effective
also accounts for repulsion of an electron by other electron

Z 
effective
= Z - S

electrons int he same shell do not screen but repel each other

EXAMPLE
Na: 1s22s22p63s2
11+ {number of protons} - 10-{number of electrons in Ne core} = 1+ {effective nuclear charge of the 3s valence electron}

Ionization Energy

 
ionization energy = minimal energy needed to remove an electron from a neutral atom
first ionization = energy required to remove first electron
EXAMPLE Na (g) --> Na + (g) + e-
second ionization = energy required to remove second election
EXAMPLE Na+ (g) --> Na2+ (g) + e-
the greater the ionization energy, the more difficult to remove the electron
moving from left to right, ionization values increase
ionization values decrease from top to bottom

Size of Atoms

 
electron clouds of colliding atoms cannot penetrate each other to any signif­icant extent
nonbonding atomic radius > bonding atomic radius
why is bonding atomic radius 0.5d?
______­___­___­___­___­___­___­___­___­___­___­_______
bonding atomic radius increases from top to bottom of table
bonding atomic raius decreases from left to right

Electron Config­ura­tions

 
when electrons are removed from an atom to form a cation, they are removed from orbitals with the largest n value
when electrons are added to an atom, they are added to the orbitals with the lowest n value

Size of Ions

 
cations are smaller than the parent atom
anions are bigger than parent atom
is there are a trend for ion size in the periodic table?
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Electron Affinity

 
electron affinity = measur­ement of attraction of the atom for the added electron
how is affinity measured?
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Notes/­Que­stions

 
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