electronegativity and molecular shape and polarity Flashcards
What is electronegativity?
An ability of on atom to attract bonding electrons when bonded in a pair
High electronegatvitity means what?
Low electronegatvitity means what?
High electronegatvity = good at pulling electrons
Low electronegatvitity = bad at pulling electrons
What is the EN chart?
0 = PURE (Pure covalent)
0-0.4= Non-polar convalent
0.5-1.6= Polar covalent
1.7+ = Ionic
What is the electronegatvitity trend?
Left to right: increases
Top to bottom: decreases
What are dipoles?
The seperation of charges within a moleculde, due to the differences in electronegatvity (creation of positive pole and negative pole)
3 types of dipoles?
Non polar bond = an equal share of electrons in a bond
Polar bond = a slightly unequal share of electrons in a bond (The creation of partial positives and partial negatives)
Ionic bond: the complete transfer of electrons, creating a positive and negative
Rule of thumb with EN differences (FE2O3)
Nonmetals + nonmetals = covalent (pure, nonpolar, covalent)
Metal + nonmetal = Ionic
—> If an ionic molecule has an EN difference of a polar covalent, that means its an ionic compound with polar covalent properties.
What is the difference between polar and non-polar?
Polar:
-> Significantly different electronegativities (0.5-1.6)
–> Unequal share of bonding electrons (electrons are closer to one nucleus than another)
-> Uneven shape
Non Polar:
No uneven distrobution of electrons
ELectron shape is symmetrical
Electronegatvitity below 0.5
What is a dipole momment?
The seperation of partial charges in a molecule (the electronegativtity difference, and where electrons are closer to one nucleus than another)
Dipoles, what are they?
The arrows indicate which atom is the more electronegative
It is a vector, therefore you add tip to tail to determine the overall polarity,
They can be cancel out, and some molecular.
-> Do not draw dipoles for anything UNDER a EN of 0.4 and OVER an EN of 1.7 (IONIC COMPONDS AND NONPOLAR MOLECULES DO NOT HAVE DIPOLES)
-> If there is no overal dipole movement, draw the dipoles and the partial pos and neg symbols
Polar molecules? (How do you know its polar and what happens)
-> EN difference of 0.5-1.6
–> ASSYMETRICAL SHAPE. (VSPER, esp for bent or linear.)
(Linear = 2 bonds, no lone pairs, bent = 2 bonds and lone pairs)
(3 bonds, if it have 0 lone pairs, its trigonal planner and cancels out, if it has 3 bonding pairs and a lone pair is a trigonal pryamid and IT DOES NOT CANCEL OUT)
-> Why? A molecule can have polar bonds but it may not be POLAR. The overall molecule is nonpolar, therefore there is no net dipole momment.
