Periodic Table Trends Flashcards
ionic radii trends
decreases from left to right
increases down a group
ionic radii decreases as atomic number increases
cations
positively charged
usually smaller because less electrons
anions
negatively charged
usually larger because more electrons
Effective Nuclear Charge
the net positive charge felt by an electron in an atom
the shielding effect of negatively charged electrons prevents higher orbital electrons from experiencing the full nuclear charged of the nucleus due to the repelling effect of inner-layer electrons
What happens to the Zeff with more electrons
the more electrons you have will increase electronic repulsion and nuclear shielding which will decease Zeff
What happens to Zeff with less electrons
less electrons means electrons get pulled closer to the nucleus which increases Zeff
chalcogens
oxygen group
pnictogens
nitrogen group
elements in same group
have same number of electrons
same chemical properties, different physical properties
diatomic atoms
form double covalent bonds to achieve full valence shell of electrons
Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine
strong Lewis acids
want to accept electrons
strength will increase with increasing ionic charge and decreasing ionic radius
want small ionic radius and large positive charge
strong Lewis base
wants to donate electrons
highly negative with lots of lone pair electrons
lower electronegativity (more easily give up electrons)
metals
low electronegativity and low ionization energy
ionization energy
the amount of energy required to remove an electron from a neutral atom
diamagnetics
no unpaired electrons
slightly repels magnets
goes against the magnetic field
parallel spin alignment
slightly bends away from field
ex: Noble gases or ions with complete pairings due to losing electrons
paramagnetic
has unpaired electrons which can interact with a magnetic field
attracted to magnets
aligned with magnetic field
anti-parallel spin alignment
magnetic field lines bend toward it
good MRI contrasting agent by enhancing signal in tissues
Pauli Exclusion Principle
each orbital can hold a max of 2 electrons, with opposite spin
Hund’s Rule
maximize the number of unpaired electrons
- want to fill up every orbital in a sublevel with one electron before pairing
Polarizability
extent to which an electron cloud of an atom can be distorted by an external charge or by an applied electric field to produce a dipole
electron affinity
measure of tendency of atom to accept electrons
will increase moving across and up the periodic table
a negative value means more likely to accept electrons
electronegativity
tendency to attract electrons within a bond
increases moving across and up the periodic table
ionization energy
opposite of electron affinity
measures energy required to remove an electron from an atom
increases with increasing atomic radius because the electrons are more dispersed and easier to remove
first ionization energy
energy required to remove the first valence electron of
second ionization energy
energy required to remove the second valence electron
which group has the lowest first ionization energy
alkali metals - group 1
because only has one electron that they really want to remove
which group has the lowest second ionization energy
alkaline earth metals - group 2
because have 2 electrons that they want to get rid of
not alkali metals because they only have 1 valence electron to give and then will have to dip into core electrons which require a lot more energy
isotopes
atoms of the same element with different number of neutrons
designated by their mass number
How to find number of neutrons
mass number - atomic number
atomic number
number of protons
determines identity of an element
atomic mass number
amu is in terms of carbon-12
sum of protons and neutrons
1 mol amu = 1 g = 6.02 x 10^23 amu
sp
linear
180 degrees
sp2 - no lone pairs
trigonal planar
120 degrees
sp3 - no lone pairs
tetrahedral
109 degrees
sp3d - no lone pairs
trigonal bipyramidal 90 degrees (for 3) 120 degrees (for 2)
sp3d2 - no lone pairs
octahedral
90 degrees
what hydridization is the most electronegative?
the more s character, the more electronegative
sp is the most electronegative
sp2 - one lone pair
bent
117.5 degrees
sp3 - one lone pair
trigonal pyramidal
107.3 degrees
sp3 - two lone pairs
bent
104 degrees
sp3d - one lone pair
sawhorse
sp3d - two lone pairs
T-shaped
sp3d - three lone pairs
linear
sp3d2 - one lone pair
square pyramidal
sp3d2 - two lone pairs
square planar
sp3d2 - three lone pairs
T-shaped
sp3d2- four lone pairs
linear
metals
good conductors of heat, malleable & ductile, easily gives up electrons
nonmetals
poor conductors, high electronegativity, unwilling to part with electrons
bond strength
decreases moving down the periodic table as acidity increases
because the larger the molecules get, the harder to hold together
acidity
the more electronegative something is, the more acidic
electron affinity
increases toward more electronegative elements
decreases moving down a column because the charge becomes more spread out
inversely related to atomic radius
ionization energy
follow same pattern as electronegativity
are the hardest to remove electrons from
as we move down a column, the radius will increase which decreases the intermolecular forces, making it easier to remove electron because not bound as tightly
What more effectively decides atomic radius?
because addition of shells has a strong effect on shielding, changes in atomic radius down a group are more pronounced than for those across a period
orbitals of water?
104.5 degree angle because lone pairs affect angles
What groups contain the longest bond lengths?
increasing atomic radius
How to determine which level of electron configuration an electron is removed from
if have a positive cation like Cu2+ –> will remove from the highest value for “n” and if they are tied then the highest “l”
ex: Osmium is [Xe]6s^2 4f^14 5d^6
if we removed 2 electrons - they would come from s group because it has the highest “n” value at 6. If there was a p group - would remove from p because they have the same “n” but p has L=1 vs s=0
How to determine which is the lower energy of a subshell
n+l rule
s=0
p=1
d=2
f=3
ex: 5d vs 6s
5d = 5+2 = 7 6s = 6+0 = 6
the lower energy is 6s and therefore the electrons would be added there first
