test 2 FUCK Flashcards
ionic bond
- held by electrostatic forces
- strong lattice structure
- usually solid at room temp, high melting and boiling points
factors that affect the melting points of ionic substances
- Coulomb’s law: greater charge = greater bond (lattice energy
- size of atoms: smaller atoms will have a greater Coulo,bic attraction (size inversely proportional to bond energy)
Ionic solids electrons are
localized, do not move around lattice, makes them poor conductors
ionic liquids
do conduct electricity, electrons are still localized but ions are free to move
metallic bonds often uses
sea of electrons
-positively charged core of metal is stationary, valence electrons move freely in a “sea”
mobile electrons in metallic bonds explain why
-metals are such good conductors of electricity
-makes them malleable and ductile (drawn into thin wire)
because deforming metal does not change environment surrounding the metal cores
metals bond w each other to form
alloys, (usually when two metals are melted into their liquid phases)
interstitial alloy
metal atoms with two vastly different radii combine (ex. steel)
substitutional alloy
forms between atoms of similar radii , some atoms are substituted
covalent bonds
shared electrons, each atom counts shared electrons as part of valence shell
all single bonds in covalent bonding are
sigma bonds
second bond in double bonds and second and third bond in triple bond
pi bonds, stronger and shorter
single covalent bond
one sigma
as you add the bonds they get
shorter and the bond energy increase
double covalent bond
one sigma and one pi
triple covalent bond
one sigma and two pi
internuclear distance
- bonds form where the potential energy of the bond is at its lowest level
- atoms very close together» potential energy is high
- atoms very far apart»> potential energy close to zero
minimum potential energy in a bond occurs
when the repulsive and attractive forces are balanced
network covalent bonds
atoms are held together in a lattice of covalent bonds
- like one big molecule, very hard, very high melting and boiling points
- ex: (SiO2 quartz)
electrons in network covalent bonds
-localized, not free to move,»_space;> moves them poor conductors
doping
process in which an impurity is added to an existing lattice
p-doping
adding an element w/ less valence electrons than needed, missing bond or hole in a lattice creates a positive charge attracting other electrons (conductivity)
n-doping
element with extra valence electrons i added to lattice, increases the negative charge and conductivity
resonance forms
when you put a double bond, it has equal chance of falling on any of the same atoms on the central atom
- means that the strength and length of all three bonds in the carbonate ion are the same, between the strength and length of a single and double bond
bond order calculation:
- single bond: bond order 1, double bond: bond order 2, etc.
- FIND by adding up the total bond order, so like 1 +1 +2 (if two single bonds and one double bond) divide by them number of resonance forms
incomplete octets
some atoms are stable w/ less than eight electrons in outer shell: hydrogen only requires 2, Boron only requires six
expanded octets
molecules with the d subshells can have expanded octets , central atom can have more than 8 electrons, but never more than twelve
SO n=3 or greater , NEVER n=2 (ex. NOT C, N, O)
explain why noble gases can form bonds
formal charge
- to determine most likely structure when multiple possible VSEPR available
- should be 0 on a neutral atom
- with a more actual formal charge … it is more likely
calculate formal charge
formal Charge = [# of valence electrons on atom] – [non-bonded electrons + number of bonds] (not bonded electrons)
molecule with more than two atoms
the shape is determined by the number of electron pairs on the central atom, which forms hybrid orbitals with a standard shape
VSEPR
- double and triple bonds are treated the same way as single bonds for predicting the overall geometry, but have more repulsive strength and may take up more space
- lone electron pairs have more repulsive strength than bonding paires»» molecules w lone pairs will have a slightly reduced bond angle
If the central atom has 2 electron pairs
sp hybridization, shape is linear
If the central atom has 3 electron pairs with 0 lone pairs
sp2 hybridization, shape is trigonal planar
If the central atom has 3 electron pairs with 1 lone pair
sp2 hybridization, shape is bent
if the central atom has 4 electron pairs with 0 lone pairs
sp3 hybridization, shape is tetrahedral. bond angles about 109.5 degrees
if the central atom has 4 electron pairs with 1 lone pairs
sp3 hybridization, shape is trigonal pyramidal
If the central atom has 4 electron pairs with 2 lone pairs
sp3 hybridization, shape is bent
if the central atom has 5 electron pairs with 0 lone pairs
the shape is trigonal bipyramidal
if the central atom has 5 electron pairs with 1 lone pair
the shape is seesaw
if the central atom has 5 electron pairs with 2 lone pairs
the shape is T-shaped
if the central atom has 5 electron pairs with 3 lone pairs
the shape is linear
if the central atom has 6 electron pairs with 0 lone pairs
the shape is octahedral
if the central atom has 6 electron pairs with 1 lone pair `
the shape is square pyramidal
if the central atom has 6 electron pairs with 2 lone pairs
the shape is square planar
coulomb’s law
E=k (+q)(-q)
—————
r2
what U know from Coulomb’s law
- greater the charge of nucleus, the more energy an electron will have
- explains binding energy
- 3s electrons will have more PE than 1s electrons
Energy and Electromagnetic radiation equation
E=hv
E. energy change (in Joules)n
h.. Planck’s constant (6.626 x 10 -34 Js)
v= frequency (in s-1)
Frequency and Wavelength
c=wv
c= speed of light (2.998 x 10 8 ms-1)
v= frequency (in s -1)
w= wavelength (in m)
nm might need to be converted to m
1 nm = 1 x 10 -9 m
usually: use speed of light to convert wavelength to frequency… then use frequency and Planks constant to find energy
in photoelectron spectroscopy
energy of incoming radiation must be conserved and any energy that does not go into breaking the electron free becomes kinetic energy :
incoming radiation energy = binding energy + kinetic energy
aufbau principle
states when building up the electron configuration of an atom, electrons are placed in orbitals, subshells, and shells in order of increasing energy
pauli exclusion principle
states that two electrons which share an orbital cannot have the same spin , on electron must spin clockwise, the other counterclockwise
hund’s rule
says that when an electron is added to a subshell, it will always occupy an empty orbital if one is available
atomic radius
-decreases from left to right
-increases down
cations are smaller
anions are larger
ionization energy
-opposite from atomic radius
-increases from left to right
-decreases down
second ionization energy is greater than the first
what is electronegativity
how strongly the nucleus of an atom attracts the electrons of other atoms in a bond
- smaller an atom is, the more effectively the nuclear charge will be felt past its outermost energy level, higher electronegativity
- closer an element is to having a full energy level, the more likely to attract electrons to complete that
electronegativity
- increases from left to right
- decreases down
