final exam review Flashcards
what are sp hybrid orbitals
orbitals formed by mixing one s and one p orbital of a central atom
what is hybridization
a theoretical process of orbital mixing to form hybrid orbitals
what does the formation of bond orbitals mean
the wave functions of the electrons are in phase
what is the basic principle of valence bond theory
a covalent bond forms when orbitals of two atoms overlap and a pair of electrons occupy the overlap region
what does greater electronegativity difference result in
larger partial charges and higher partial ionic character
what is ON equal to
the number of valence electrons minus the number of shared electrons plus the number of unshared electrons
what is an oxidation number
the charge that an atom would have if all of the atoms attached to it were removed along with the electron pairs it is sharing with other atoms
electronegativity is ________ related to atomic size. why?
inversely related. the nucleus of a smaller atoms is closer to the shared pair than the nucleus of a larger atom
in substances what are most atoms joined by
polar covalent bonds, partly ionic and partly covalent
what makes a good fuel
covalent compounds with weak bonds and relatively less O
what is a fuel
a material that reacts with atmospheric oxygen to release energy
what is delta H r related to
sigma delta H reactant bonds broken + sigma delta H product bonds formed or sigma BE reactant bonds broken minus sigma BE product bonds formed *these are only for gas phase reactions
are covalent substances generally good conductors
no, electrons are localized and no ions are present
do molecular covalent substances have high melting and boiling points
no they have low mp and no because they have strong bonding forces between atoms within the molecule and weak intermolecular forces between separate molecules
do network covalent solids have a high melting and boiling points? why?
yes due to the large amount of energy required to rearrange covalent bonds
the trend in bond lengths is __________ to the trend in bond energy
opposite
as we go left across a group what does bond length do
increases
what does a higher bond order result in
a shorter bond length and higher bond energy
strong bonds are ______ in energy while weaker bonds are __________ in energy
lower, higher
why is bond energy always positive
bond breakage is an endothermic process
what is electron affinity
the energy change accompanying the addition of 1 mol of electrons to 1 mol of gaseous atoms of ions
what does the magnetic quantum number prescribe
the 3-d orientation of the orbital in the space around the nucleus
what are orbitals
mathematical solutions to the schrödinger wave equation
what are orbitals
mathematical solutions to the schrödinger wave equation
what does a higher nuclear charge do
it increases nucleus-electron attractions, lowering sub shell energy and stabilizing the atom
what is special about hydrogen and it’s energy state
it’s the only atom whose energy state depends completely on the principal quantum number
what does the principal quantum number specify
the energy level (shell) of the H atom, the higher the n value the higher the energy level
what is the principal quantum number
a positive integer that indicates the relative size of the orbital and therefore the relative distance from the nucleus of the peak in the radial distribution plot
what is psi (trident)
the wave function
what is the angular momentum quantum number related to (L)
the shape of the orbital
what is the major consequence of the exclusion principle
an atomic orbital can hold a maximum of two electrons and they must have opposing spins
what does penetration do
it increases the average effective nuclear charge for its electron and it decreases the shielding of a 2s electron by the 1s electrons
what does each solution to shrodingers equation give
an energy state associated with a given atomic orbital
:(
:(
what do transition metals lose first s or d electrons
s
what species are paramagnetic and what do they do
they are species with 1 or more unpaired electrons; they are attracted by an external magnetic field
elements in the same group have similar _______ and similar patterns of _______
valence electron configurations and reactivity
what are diamagnetic species and what do they do
they are species with all electrons paired, they are slightly repelled by an external magnetic field
are cations larger or smaller than parent atoms
smaller
are anions larger or smaller than parent atoms
larger
what do main group s block metals do
lose all electrons with the highest n balue
where do non metals gain electrons
in the p orbitals of the highest n value
what is penetration
the process by which an outer electron moves through the region occupied by the outer electrons to spend part of its time closer to the nucleus
what is the exclusion principle
no two electrons in the same atom can have the same four quantum numbers
which electrons are removed first from main group metals p or s
p
what does metallic behavior do across a period and down a group
in increases from right to left and down
what do elements that have low IEs and less negative EAs tend to do
lose electrons easily but attract them weakly
t/f elements that have high IEs and highly negative EAs tend to lose electrons with difficulty and attract them strongly
T
what does ionization energy do down a group? across a period?
decreases, increases
why does IE increase the more electrons you pull away
you are pulling electrons from a more and more positive ion
t/f ie2> ie1
t ALWAYS
what is ionization energy
the energy required to completely remove 1 mol of electrons from 1 mol of gaseous atoms or ions
as period number increases what happens to zeff
it rises significantly
which element is the biggest? the smallest?
Fr, F
what happens as zeff increases
outer electrons are pulled closer to the nucleus
what is bond energy
the energy needed to overcome the attraction between the nuclei and shared electrons, it is defined as the standard enthalpy change for breaking the bond in x mol of gaseous molecules
what is bond order
number of electron pairs being shared by a given pair of atoms
where is is the greater electron density in a covalent bond
between the nuclei
what causes a covalent bond
the balance between nuclei attracting the electrons and the electrons and nuclei repelling each other
what is the main way atoms interact
sharing electrons
why do ionic compounds have high mp and bp
large amounts of energy are required to free ions from their positions and separate them
when do ionic compounds conduct electricity
when melted or dissociated where ions can move and carry a current
what are typical physical behaviours of ionic compounds and why do they have these behaviours
they are hard (they do not dent), brittle (crack without deforming), and they are rigid (do not bend). there are strong attractive forces holding ions in specific positions
what does delta H lattice =
(cation charge * anion charge)/(cation radius + anion radius)
lattice energy is __________ to electrostatic energy
directly proportional
t/f there are periodic trends in lattice energy
t
what is lattice energy
the enthalpy change that accompanies the reverse of the equation of formation
is energy absorbed or released during electron transfer
absorbed
what form of matter are ionic compounds typically
solid
do 100% ionic or covalent bonds exist?
no, gradations of each type of bond occur
are electrons in metallic bonding localized or delocalized
deloacalized, they move freely throughout the piece of metal
in metallic bonding what is the metal iron core comprised of
nucleus plus inner electrons
what happens during metallic bonding
the enormous number of atoms in a sample of metal “pool” their valence electrons into a “sea” of electrons between and around each metal ion core
how does covalent bonding occur
the nucleus of each atom attracts the valence electrons of the other, drawing the atoms together
where does covalent bonding commonly occur
between non-metal atoms
what occurs during ionic bonding
electron transfer
where does ionic bonding occur
between atoms with large differences in electronegativity (usually between groups 1/2 and 17/the top of 16
what are resonance structures
two or more lewis structures for a molecule that cannot be adequately depicted by a single structure
what is electron pair deloaclization
the process by which electron density is spread over several atoms rather than remaining between the two atoms
what is a resonance hybrid
the weighted average of the resonance structures of a molecule
what is formal charge
the hypothetical charge on an atom in a molecule or ion, equal to the number of valence electrons minus the sum of all the unshared and half of the shared electrons
is formal charge the same as oxidation number
no
what are the electron deficient atoms
Be or B