atomic structure and bonding Flashcards
what is a mass spectrometer
machine that measures the mass + abundance of particles
what does the hydrogen emission spectrum show
shows there are specific energy levels that have patterns
what are the 2 evidences for ions
migration of ions
x-ray diffraction
what is migration of ions
wet filter paper with coloured ions in has a charge flowing through it
if colours move, they must be charged ions, not neutral atoms
what is x-ray diffraction
x ray tube shoots a beam through a crystal and shield
this displays where the ions are
gaps show repulsion and therefore charge
what does an s orbital look like
spherical
centred on the nucleus
come on their own
what are the 4 orbitals in order
S
P
D
F
what does a p orbital look like
at right angles
come in sets of 3
what do d orbitals look like
come in sets of 5
what do f orbitals look like
come in sets of 7
what orbitals do al l atoms have
all
what is Aufbaus’s rule
fill orbitals from lowest energy
what is Pauli’s rule
two electrons sharing an orbital have opposite spin while orbiting
what is the acception for filling orbitals
fill 4s orbital before the 3d orbitals
also lose 4s before 3d if +ion
what is Hund’s rule
degenerate orbitals fill singly, before pairing up
where do the orbitals goon the periodic table
ionic structure -ions in the lattice
+ions and -ions alternate
in a giant ionic lattice
ion conductivity needs
high conductivity in liquid or aqueous states
no conductivity in solid states
ionic bonding definitions
electrostatic attraction between oppositely charged ions
what does ionic charge depend on 2
- charges of each ion
-radii of each ion
properties of simple molecules
low MP
don’t conduct
some soluble in water
define dative covalent bond
electrostatic attraction between positively charged nuclei of bonding atoms and shared pair of electrons where both electrons come from the same atom
when expanding octets, why are 2 extra bonds made
energy needed to promote 3d-3s is less than the energy released when 2 extra bonds form
order of bonds energy in carbon
as number of bonds increase, bond energy increases
2 factors that affect covalent bonds strength
number of bonds and size of atoms
why do bigger atoms form weaker covalent bonds
bigger atoms
longer bonds
further from nucleus
attraction is weaker
bonds is weaker
define structure of metals
giant metallic lattice
define bonding in metals
electrostatic attraction between positive metal cations and a negatively charged sea of delocalised electrons
what does the strength of metallic bonding depend on 3
cation charge
cation radius (smaller means stronger)
number of delocalised electrons
why can metals conduct
delocalised electrons are free to move throughout the structure
why are metals malleable
layers of metal ions cam slide over each other without disruption the bonding
what is VSEPR
valence (shell) electron - pair repulsion
what shape has minimum pair repulsion
2-6 pair shapes
what would 2 pairs
look like
be called
angle sizes
linear
what would 3 pairs
look like
be called
angle sizes
trigonal planar
what would 4 pairs
look like
be called
angle sizes
tetrahedral
what would 5 pairs
look like
be called
angle sizes
trigonal bipyramidal
what would 6 pairs
look like
be called
angle sizes
octahedral
why do lone pairs cause a change in shape
lone pairs attract more than bonding pairs
what do 3 bonding pairs and 1 lone pair
look like
are called
and angle sizes
trigonal pyramidal
what do 2 bonding pairs and 1 lone pair
look like
are called
and angle sizes
bent
what happens to the shape of the molecule if there are double bonds
double bonds repel a lot more
so bonding electrons move doen
for bigger molecules, how do you draw them
alanine - apply VSPER to each individual atom in the larger molecule
how to calculate number of lone pairs
add middle element and number of bonds
divide by 2
define electronegativity
the tendency of an atom (of an element) to attract bonding electrons
what elements have the lowest electronegativity
metals
what elements have the highest electronegativity
non metals
what bonding has a low electronegativity difference and a low mean electronegativity
metallic
what bonding has the highest electronegativity difference
ionic
what bonding has low electronegativity difference and high mean electronegativity
covalent
mps why electronegativity increases up a group 3
atomic radius decreases
less electron shielding
stronger attraction to nucleus
mps on why electronegativity increases across a period
similar radius and shielding
nuclear charge increases
stronger attraction to the nucleus
on a graph of mean electronegativity and electronegativity difference, where does each bonding go
ionic top
metal bottom left
covalent bottom right
diamond structure electron arrangement
2,4
diamond number of c bonds for each atom
4 (max number)
what temp does diamond sublime
4000 degrees Celsius
strong c-c bonds need to be broken
diamond conductivity
doesn’t conduct
all electrons held between atoms in structure
diamond hardness
covalent bonds operating in 3 dimensions
diamond solubility
insoluble in water and organic solvents
no attraction that could outweigh carbon covalent bonds
graphite number of c bonds for each atoms
3
4th electron becomes delocalised
how do graphite sheets stay together
atom within sheets held together by strong covalent bonds
delocalised electrons add extra attraction
what are van der waals dispersion forces in graphite
dipoles induced in sheets above and below
graphite melting point
high
strong covalent bonding
graphite solubility
insoluble in water and organic solvents
no attraction that could outwigh carbon covalent bonds
graphite density compared to diamond
less dense
large space between sheets
graphite feel
soft and slippery
layers slide over each other
graphite conductivity
conducts electricity
deleocalisede-s free to move throughout the sheets
silicon dioxde melting point
1700 degrees Celsius
strong silicon-oxygen covalent bonds
silicon dioxide hardness
hard
strong silicon-oxygen covalent bonds
silicon dioxide conductivity
doesnt conduct
all electrons trapped in structure
silicon dioxide solubility
insoluble in water and organic solvents
no attraction that could outweigh covalent bonds
define polar bonds
covalent bonds are polar if there is a significant electronegativity difference
define polar molecules
a molecule with asymmetrically arranged polar bonds
how to test if a liquid contains polar molecules
jet of liquid bends away from a charged rod
what IM forces have 0-30 kJmol
london forces
what IM forces have 30-50kJmol
dipol-dipol bonding
what IM forces are 50-150 kJmol
hydrogen bonding
define london forces
attraction between induced dipoles
What IM forces are more than 151 kJmol
covalent bonds
wat does the strength of london forces depend on
no of electrons per molecule
consider the shape of the molecule
what shape of molecule has stronger london forces and why
longer thinner molecules
can pack closer together
slightly stronger attracton
what moleular substances have london forces
all
how are dipoles induces in solids
electrons move randomly
more move on way at one point
inducing a dipole
explain how a dipole appears
as son as more elctrons go one way than the other, an instantaneous dipole appears - inducing the other dipole
what are permanent dipoles called
dipole-dipole forces
whats the difference between dipole-dipole forces and london forces 2
dipole-dipole forces are stronger because dipoles are already there
molecules are polar for dipole-dipole forces
why does polarity increasing increase hydrogen bond strength
weaker atom is exposed to the outside of the electron cloud
conditions for there to be a hydrogen bond
a N/O/F atom bonded to a hydrogen atom
hydrogen atom can form a hydrogen bond with another N/O/F atom with a spare electron pair
define a Hydrogen bond
n/Fattraction between a H (alpha+) in O-H/N-F/F-H and a lone pair on o/
