Flashcards
Can molecules with polar bonds be non polar?
Yes if there is no net dipole moment
What is the shape of an s orbital?
spherical
what is the shape of p orbital?
bi-lobed
Which type of bonds form between atoms with small differences in electronegativity (.4-1.7)?
polar covalent bonds
Which type of bond forms between atoms with the same electronegativities?
non polar covalent bonds
What is a coordinate covalent bond?
one in which a pair of bonding electrons originates from just one of the atoms.
(T/F) A dipole moment exist when a molecule has a separation of positive and negative charges.
true
What is the formula for calculating formal charge on an atom involved in a covalent bond?
Formal charge= V-(1/2 N bonding + N nonbonding)
What are resonance structures?
2 or more non-identical lewis structures for the same molecules
(T/F) A lewis structure with small or no formal charges is preferred over one with large formula charges.
true
Should a negative formal charge be placed in highly electronegative atoms or weakly electronegative atoms?
highly electronegative atoms.
what are the bond orders of single, double, and triple bonds?
single=1st order
double=2nd order
triple=3rd order
(T/F) A triple bond is longer than a single bond..
False
What is a bond energy?
amount of energy required to separate two bonded atoms
Can both bonding and nonbonding electrons be valence electrons?
yes.
nonbonding e- = not involved in a bond
bonding e- = involved in a bond
Which type of elements contains the halogens?
group VIIA
Which group of elements contains alkaline earths?
group IIA
Which group of elements contains noble gases?
group VIIIA
Which groups of elements contain the transition metals?
groups IB to VIIIB
what is an ionic bond?
transfer of electrons between two atoms
what is a covalent bond?
sharing of electrons between two atoms
what is a polar covalent bond?
has properties of ionic and covalent bonds. electrons are shared but not equal.
what is a cation?
positively-charged ion
(T/F) Metals are found on the left side of the periodic table and are good conductors of electricity and heat.
True
(T/F) Non metals are found in the middle of the periodic table and are malleable, ductile and shiny.
False
(T/F) Metalloids are found between the metals and nonmetals and have varying properties.
True
Which group of elements contains the alkali metals?
Group IA
What is the electron affinity trend within the periodic table?
increases left to right across a period & up a group.
(T/F) Group VIIIA elements have high electron affinities.
False
What is electronegativity?
measure of attraction an atom has for the electrons in a chemical bond.
What is the electronegative trend within the periodic table?
increases left to right across a period and up a group.
What happens to the number of electrons when one moves from left to right across a row?
added as you move across a row.
Are electrons more tightly held or less highly held as one moves down a column?
tightly
What is the atomic radii trend within the periodic table?
decrease as you move from left to right across a period and up a group.
Does a period run horizontally or vertically?
Horizontally
Does a group run horizontally or vertically?
Vertically
(T/F) Groups have the same valence configuration and have similar chemical properties.
True
Which group A or B contains the representative elements?
A
(T/F) one amu is equal to 1/12 the mass of a carbon-12 atom.
True
how many particles are in a mole?
6.02 x 10 ^23
what is atomic weight?
reflects the number of grams per mole of the element. The atomic weight is usually derived from a weighted average of the naturally occurring isotopes of the element.
what is an isotope?
different form of the same element due to a different number of neutrons.
What are the 3 steps for determining geometric configuration?
- draw lewis structure
- count bonding and non bonding electron pairs in the valence shell of the central atom
- arrange the electron pairs around the central atom so that they are as far apart as possible.
what is an anion?
negatively- charged ion.
which type of bonds forms between two atoms with substantial differences in electronegativities (>1.7)?
ionic bonds
(T/F) all atoms bond according to the “octet rule”
False.
what are some characteristics of ionic compounds?
crystal lattices
conduct electricity in solution
high melting
boiling points
what is ionization energy?
energy required to completely remove an electron from an atom.
compare the values of the first ionization and second ionization energy of an atom.
second ionization higher than first
what is electron affinity?
energy released when an atom accepts an electron.
How s a photon’s energy related to its wavelength?
energy is inversely proportional to wavelength
How is a photon’s energy related to its frequency?
energy is proportional to frequency
What is a paramagnetic material?
unpaired electrons
What is a diamagnetic material?
no unpaired electrons
How many fourth quantum numbers (ms) are possible for an electron?
What are they?
two.
+1/2 and -1/2
What is Hund’s rule?
electrons will fill to create the max number of half-filled orbitals.
what are the first four subshells?
s,p,d and f
what is the formula for the max number of electrons allowed in a subshell?
(4l+2)
what does the magnetic (3rd) quantum number (ml) represent?
represent an orbital within a subshell. The possible values range from -l to l
How many orbitals can each subshell accommodate?
7
What are three types of intermolecular forces?
dipole-dipole interactions
hydrogen bonding
dispersion forces
state the intermolecular forces in order of increasing strength.
dispersion forces
which molecules, polar or non polar, typically have higher boiling points?
polar molecules typically have higher boiling points.
Geometric arrangement:
CO2
Linear
Geometric arrangement:
BH3
trigonal planar
Geometric arrangement:
NH3
pyramidal
Geometric arrangement:
CH4
tetrahedral
Geometric arrangement:
PCl5
trigonal bipyramidal
Geometric arrangement:
SF6
octahedral
How many more protons are in a carbon-14 from than in a carbon-12 atom?
none.
what is an atomic emission spectrum?
electrons fall to their ground state
what is an atomic absorption spectrum?
electrons are excited to higher energy levels.
define Heisenberg uncertainty principle.
it is impossible to know both the momentum and position of an electron at the same time.
what are valence electrons?
electrons farthest from the nucleus, as well as many electrons available for bonding.
Define the Pauli exclusion principle?
no two electrons in an atom can have the same quantum numbers.
what does the principal (1st) quantum number (n) represent?
shell
what is the maximum number of electrons allowed in the second shell (n=2)?
2n^2
What does the azimuthal (2nd) quantum number (l) represent?
subshell
Classify the Rxn:
A+X -> AX
Combination or additon
Classify the Rxn:
AX -> A + X
decomposition
Classify the Rxn:
AX + B -> BX + A
single displacement
Classify the Rxn:
AX+ BY -> AY + BX
double displacement
Classify the Rxn:
HA (aq) + BOH (aq) -> AB (aq) + H2O
neutralization
What is an empirical formula?
simplest whole number ratio of the element in a compound.
What is a molecular formula?
actual number of atoms each element present in a molecule of the compound.
what is the formula for calculating % composition
mass of X compound / MW of compound x 100%
What is molar mass (molar weight)?
Number of grams per molecule
what is the formula for gram equivalent weight?
Molar mass / n = Gram equivalent weight.
what is the formula for calculating equivalents?
Weight of compound/ Gram equivalent weight= equivalents
How do increasing temp and reactant concentration affect the rate of the reaction?
increases the rate of most reactions.
can the medium in which a reaction takes place affect the reaction rate?
yes
how does a catalyst increase reaction rate?
by decreasing activation energy
what is the reaction rate of the following one step reaction:
2A + B -> A2B
Rate = k [A]^2 [B]
what is the enthalpy change of a reaction?
difference between potential energy of the products and the potential energy of the reactants
what is the general formula for the rate law of the following reaction?
aA + bB -> cC + dD
rate= k [A]^x [B]^y
What is the reaction order for the following rate law?
rate= k [A] [B]^2
Reaction order =3
x=1, y=2, and order =x+y
Is the rate of a zero order reaction dependent on the concentration of the reactants?
No, a zero order reaction has a constant rate that is independent of the concentration of reactants.
what is an elementary reaction?
reaction that can not be decomposed into other reactions
(T/F) A complex reaction can be broken down into two or more elementary reactions.
True
what is an intermediate?
complex that appears during the course of a reaction but does not appear in the net reaction or as a final product.
what is the rate determining step of a reaction?
slowest step of a reaction
what is theoretical yield?
amount of product that can be predicted
what is actual yield?
amount of product actually isolated from the run experimentally
What is percent yield and what is the formula for calculating it?
relationship between actual yield and theoretical yield
actual/theoretical x 100%
What is the equilibrium constant expression for the following reaction:
A+ 3B -> 2C + 2D
Keq= [C]^2 [D]^2 / [A] [B]^3