Chem Quiz #3 Flashcards
Core e-
e- in inner shells that don’t participate in chemical reactions
Valence Isoelectronic
atoms in some period group w/ same # of valence e-
G.N. Lewis
introduced cubicle atoms & knew of core e- & that there are 8 valence e- in an octet
Octet Rule w/ exception
atoms combine to achieve filled shells (octets) of e- & have structures that are isoelectronic w/ noble gases
Exception: hydrogen (duet) & transition elements (18 e- rule)
Lewis Structures
assumes molecule is composed of atoms bound together w/ atomic orbitals to share e- pairs
BH3
only has 3 valence e- & doesn’t have an octet configuration (sextet) (electronically unsaturated)
HYPOvalent
Empty Orbital
Space around atom where B in BH3 would LOVE to form a pair
Orbitals
Place to put e-
Elements ____ of Carbon have empty orbitals
left
Elements ____ of Carbon have filled orbitals (lone pairs)
right
Dative/Coordinate Covalent Bonds w/ ex
single atom provides both e-
donor acceptor bond
ex. N in NH3 provides e- to bond NH3 w/ BH3
How to calc. formal charge
Formal Charge = group valence - #e- in lone pairs - # bonds
Dative Covalent Bond
forms w/ Lewis Acid (A) & Lewis Base (B)
arrow between bonds indicates
ex. N-B
N has (+) formal charge and B has (-) formal charge
e- pair acceptor
Lewis Acid
e- pair donor
Lewis Base
how to calc. # e- in central atom?
group valence - nearest multiple of 8
ex. 03 has 18e- and nearest multiple of 8 is 16 soooo 18-16=2e- in middle atom
Formal Charge
Formal Charge = group valence - #e- lone pairs - # bonds
Dipole Moment of CO
carbon is (-) even tho oxygen is more electron(-)
CO & N2 are isoelectronic & both have triple bonds butt
N2 doesn’t have any formal charges
formal charges or dative bonds should always be incorporated when representing the bonding in molecules
how to calc #e- in valence shell
e- in valence shell = # valence e- in neutral atom + #bonds - formal charge
Resonance Structures
differ in e- position & not nuclei position
Bond order in O3
O-O=O has bond order of 1.5
