Chapter 5 Flashcards
why do chemical bonds form
to lower potential energy between charged particles
Exceptions to Octet Rule
Boron wants 6
Aluminum wants 6
Be wants 4
Who does the octet rule apply to
main group elements
single non-bonding electron
radical
non-bonding pair of electrons
localized on the atom (belong to only one atom), in atomic orbitals
coordinate covalent bond
electrons that form the bond both came from the same atom
Electronegativity
ability of an atom to attract electrons to itself in a covalent bond
EN trend
increases across a period, decreases down a group
EN of F
4.0
EN of C
2.5
Difference in EN of nonpolar covalent
0-0.4
Difference in EN of polar covalent
0.4-2.0
Difference in EN of ionic
2.0+
Dipole moment
shift in electron density, uneven distribution
Magnitude of dipole moment
µ=qr
q=charge of electron in Coulumbs
r is in meters
theoretical value, if electron were fully transferred
Larger magnitude of dipole moment
more polar the bond
Percent Ionic Character
actual dipole moment/theoretical dipole moment
elements that can have expanded octet
n=3 and higher (d orbitals)
Best Lewis structure
greatest resonance contributor
negative formal charge
most EN atom, exceptions if needed to complete octet
Bond energy
amount of energy needed to break 1 mole of that bond in the gas phase, also called bond enthalpy, delta H, positive, endothermic, absorbs energy
greater bond energy
stronger bond
1 Angstrom
10^-10 meters
straight line bond
bond is in plane of paper
