exam 3 Flashcards
what effect does bonding have on potential energy
it LOWERS potential energy between positive and negative particles
ionic bond
nonmetal & metal (electron transfer)
covelant bonding
nonmetal & nonmetal (electron sharing)
metallic bonding
metal & metal (sea of electrons)
strongest type of bonds
Lewis dot structures use valence electrons from the…
group #
octet rule
when atoms bond they lose, gain or share electrons to attain a filled outer layer of 8 (H & Li are exceptions)
ionic bonding model
the transfer of electrons from metal atoms to non metal atoms
(atoms want to reach the nearest noble gas)
lattice energy
the enthalpy change associated with the process of separating 1 mol of ionic solid into gaseous ions
lattice energy increases with…
decrease in ionic radius
increase in ionic charge
bond order
the # of electron pairs being shared by a given pair of atoms
bond energy/strength
energy to separate = energy to form
always positive: breaking bonds is ENDOTHERMIC
bond length
the distance between the nuclei
higher bond order results in…
smaller bond length &
higher bond energy
molecular covelant substances are ______ and have _______ melting points
weak,low (due to weak forces between them)
breaking bonds
endothermic (positive)
forming bonds
exothermic (negative)
highest lattice energy
highest product of charges + smallest radius
charge first/radius second
electronegativity
relative ability of bonded atoms to attract shared electrons
oxidation #
valence e - (# of shared e + unshared e)
shared e go to the most electronegative
bond order
(# of electrons bonded - # electrons not bonded) divided by 2
formal charge
= # of valence e ➖ (# of unshared valence ➕ 1/2 # shared valence e)
formal charges must sum….
to the actual charge of the species
0 for a molecule / ionic charge for an ion
picking the best resonance based on FC
prefer smaller formal charges, most negative FC should be on the most electronegative
formal charge is used to….
examine resonance structures & determine best fit
electron arrangement
bonding & non bonding groups around a central atom (can yield varied molecular shapes)
molecular shape
relative position of the nuclei bonding groups ONLY
linear
2 bonding groups
180° ideal bond bond angle
lone pairs ______ the angle between bonding pairs
decrease
the ______ the bond angle the weaker the repulsion
greater
double bonds have more electron density and repel _________ more than they repel eachother
electrons in single bonds
trigonal planar
3 electron groups
120° ideal bonding angle
when you have 1 lone pair
the structure is BENT
tetrahedral arrangement
4 electron groups
109.5° ideal bond angle
4/0: tetrahedral
3/1: trigonal pyramidal
2/2: bent
trigonal bypriamidal
5 bonding groups
3 120° & 2 90° ideal bond angles
5: trigonal bypriamidal
4/1: see-saw
3/2: T-shaped
2/3: linear
octahedral
6 electron groups
90° bond angles
6: octahedral
5/1: square pyramidal
4/3: square planar
covenant bonds are polar when…
the atoms have different electronegitivities
non-polar
net dipole= 0
everything cancels out
equal sharing of electrons
polar
net dipole >0
unequal electron sharing, asymettrical
Born Haber Cycle
- sublimation
- dissociation
- ionization
- electron affinity
- formation
- lattice energy
atomic radius is highest …
bottom left corner
electronegativity is highest…
top right corner
when oxygen is present the heat_____
decreases
repulsion
high potential energy
attraction
low potential energy
bond length _____ when atomic radius increases
increases
bond polarity and ionic character increase with a _____
increasing difference in electronegitivity
electronegativity increases….
diagonally from bottom left to upper right
bond strength INCREASES as atomic radius
DECREASES
molecule will be non polar if:
the shape around the central atom has no lone pairs (unless square planar or linear)
if all atoms around the central atom are the same
mass=
concentration x molar mass x volume
mol x gram/mol x liters
mass=
concentration x molar mass x volume
