unit 2 test Flashcards
how do you determine central atom
least electrognegative
listed 1st in formula
when making lewis diagrams
add up all the VE for the compound
add up ionic charges also
(negative charge means add electrons and positive charge means take away electrons)
for ions also put square brackets and the charge on the outside
a line between dots represents
a shared pair of electrons forming. a single covalent bond
ionic bonds are stronger when
charges are larger and ions are smaller
metallic bonding
occurs between metal bonds
metal attractions due to cations being attracted to a de localized sea of electrons
alloys
mixtures of metals
interstitial alloys
atoms added to metals are small and fit between metal atoms, in hole(interstices)
substitutional alloys
atoms added to metal have similar radii so they replace atoms in lattice
which atoms have expanded octets
and what are octets
central atom has more than 8 around it
3rd periods and below have expanded octet
bond length influenced by
the size of atoms core and bond order
bonds w a higher order are shorter and have larger a bond energies
interaction strength is proportional to
charge of each ion
large charges leas to stronger interactions
covalent bonds occur at
lowest energy state
attractions between nuclei is greatest for shared electrons
repulsión a between electrons and between the nuclei is the least
isomer
same number and type of atoms but different arrangements
large atomic radii increases..
bond length
long bond length decreases…
bond energy
for electrons to be conduct electricity they need to be
free moving/flowing
particles need to be charged
what does VSEPR stand for
valence shell electron pair repulsion
how do lone pairs affect the bond angle
increase the repulsion
bring other atoms closer together so the bond angle is smaller
what does hybridization and hybrid atomic molecule describe?
arrangement of electrons around a central atom
electron domains
single bond, double bond lone pair, etc all count for an individual electron domain
sp2
how many s and p orbitals
how many electron domains
1 s orbital, 2 p orbitals
3 electron dominas
Electrons involved in binding among metal atoms are
Equally shared and NONdirectional bonds
For the potentials energy graphs
Would cl be outside or inside the graph of br
Cl is higher up(vertically),above br
Outside graph of br
Smaller atomic radius means more outside, greater graph
For the potentials energy graphs
Would F be outside or inside the graph of C
F is more to the right, than C horizontally on the periodic table
Outside the graph of C
Smaller atomic radius means more outside, greater graph
What is the hybridization of 3 areas w/ electrons or a double bond
Sp^2
2 areas w/ electrons or triple bonds
Sp
4 electron areas (single bond)
Sp^3
What is bond order
Bond order is the # of bonding pairs of e- between 2 atoms
A single bond has a bond order of of 1
what do metal elements have with their e-
a sea if electrons
electronegativity of pure covalent
less than .4
electronegatovity of polar covalent bonds
0.4-1.8
ionic bonds eñectrongetivity
greater than 1.8
polarity
difference greater than .5
ionic bonds, electrons are
transferred from cation to anion
what are ionic solids called
salts
covalent bonds electrons are
shared between atoms
which direction does the dipole arrow point
towards the more electronegative atom
unstable bond
would look at graph
potential energy greater than 0
stable bond
would look at graph
potential energy less than 0
y-axis of graphs
energy required to break the bond(endothermic process)
x-axis of graph
distance between atoms, bond length
use peale of graph to determine
bond energy and length
greater lattice energy
consider ionic radius- smaller IONIC radius means higher lattice energy because ions can get closer together
consider distance between elements horizontally (greater charge difference means greater lattice energy)
octet rule
except for H and B all atoms should end up with 8 electrons around them
how to determine center atom of molecule
the first written ir the most electronegative(upper right corner)
HONC
1234
means at most those atoms can have that many electrons(they can have less)
usually carbon does have 4 however
best or most dominant lewis diagrams
have a total formal charge of 0
or
most negative formal charge should go to the most electronegative element
how to find formal charge
of total VE minus individual VE in that diagram minus # of bond in that diagram
what does VSEPR
valence shell electron pair repulsion
each electron domain counts equally no matter the…
bond order(single, double, etc.(
what do lone pairs do to an electron structure
they take up more space, changing the shape of the bond
because
the other electrons are repelled by the lone pairs causing the other electrons to be closer together
nonpolar molecules
lewis diagram is symmetrical
polar molecules
lewis diagrams have lone pairs
how to find hybridization
electron domains minus one
double bond hybridization
sp2
3 electron domains usually ; 3 areas with electrons USUALLY
triple bond
sp2
2 areas with electrons usually
4 electron areas
sp3
if there is a C-C bond in the center or more (C-C-C, C-C-C-C,..)
then..
count it as a single central atom
pretend or redraw the element as a central atom to find the appropriate hybridization
Lattice energy
Liek bond energy
Energy required to completely separate one mole of solid ionic compounds into gaseous ions
Ionic substance
What are there boiling points
High melting and boiling points
Do ionic solids conduct electricity
No they do not conduct electricity
How do ionic compounds act in polar solvents or non polar solvents
Solubility?
Soluble in polar solvents
Insoluble in non polar solvents
Elements in 3rd period can do what with their octet
Expand their octet, have more than 8 electrons when they are the central atom
The bond length in resonance is
The average of the bonds present
Sigma bond is formed from
Overlapping orbitals from a single bond
Pi bonds are formed from
Unhybridized p orbitals with double and triple bonds
Equation for resonance drawing
of bonds/# of atoms it’s shared by
3/2
A double bond and a single bond between Oxygen
single sigma bond
1
double sigma bond
1
triple sigma bond
1
single pi bond
0
double pi bond
1
triple pi bond
2
zero dipole moment
no partial charge on either end of the covalent bond
does SO2 have a dipole moment
no because they both have the same charge (-2)
NF3 hybridization
sp^3
lone park counts as electron domain also
electrons domains(4) - 1 = 3
valence electrons shared between atoms of similar electoronegativoty constitute a
non polar covalent bond
when considering whether a structure is polar
HCN
consider if the shape is symmetrical then also consider electronegativity , dipole moments
polar
when reading potential energy vs inter nuclear distance graphs consider
the first part where the graph crosses the x axis and that aligns with bond length
(not the last part)
stable point of potential energy graph
lowest point of potential energy graph
