Transcript Periodic Trends - My Chemistry Class

WHAT
Radius
Electronegativity
Ionization Energy
HOW
WHY
Periodic Trends
How do we measure atomic radius
 Ideally - measure the radius from nucleus to edge of the atoms
last filled orbital (valence orbital)
 CAN’T!!! --- Because orbitals are just estimations of where
electrons might be. The edge is “fuzzy.”
 So we measure half the
distance between two identical
atoms bonded together
Atomic Radius
INCREASES from RIGHT to LEFT, TOP to BOTTOM
Why does ATOMIC RADIUS increase the
way it does?
 INCREASES DOWN a GROUP
Adding more energy levels
 DECREASES LEFT to RIGHT ACROSS A PERIOD but -
ADDING more protons, neutrons, electrons.
 SOWHY DOESN’TYOUR RADIUS GET BIGGER????
More protons = the more they can PULL IN e= SMALLER radius
GREATER EFFECTIVE
NUCLEAR CHARGE = SMALLER RADIUS
Electronegativty
Official Definition of Electronegativity:
A measure of the ability of an atom in a chemical
compound to attract electrons from another
atom in the compound
What that REALLY means:
How strongly it can pull on electrons from
another atom
Electronegativity
INCREASES from LEFT to RIGHT, BOTTOM to TOP
Why does ELECTRONEGATIVITY increase
the way it does?
 INCREASES LEFT to RIGHT
Atoms are closer to filling valence shell, so they REALLY
want more electrons
 INCREASES BOTTOM to TOP
Electrons are CLOSER to nucleus – can pull harder on
electrons
Ionization Energy
Official Definition of Ionization Energy:
The energy required to remove one electron from
a neutral atom of an element
What that REALLY means:
How hard it is to remove an electron from the
atom (more energy needed, the harder it is)
Ionization Energy
INCREASES from LEFT to RIGHT, BOTTOM to TOP
Why does IONIZATION ENERGY increase
the way it does?
 INCREASES LEFT to RIGHT
atoms want a full valence shell…they DONT want to give
away their electrons IF they are almost full!
 INCREASES BOTTOM to TOP electrons are
CLOSER nucleus so they are being held onto tightly