General Chemistry Flashcards
What is going from solid to liquid phase?
melting (Fusion)
Liquid to a gas is called?
Vaporization (boiling)
What is it to go from gas to liquid?
condensation
What is it to go from solid to gas?
sublimation
What is it to go from gas to solid?
Deposition
What is the triple point?
Where all three phases are existing at the same pressure and temperature
What is the critical point?
Point where you cannot tell the difference between liquid and gas
On a phase diagram, which way would be endothermic?
Back to the previous phase
ie. gas to solid = sublimation
is endothermic
How do you calculate the formal charge?
Formal charge = (valence e-) - (Sticks + Dots)
Ideal formal charge = 0
Explain Resonance Structures
In molecules with open p orbitals, electrons can be delocalized or shared among atoms in more than one way, creating extra stabilization
What are the structures for NO3-, NO2+, NO+, NH2OH
List them in order from strong to weak bond strength
NO+ > NO2+ > NO3- > NH2OH
NO3- sometimes has single bonds and sometimes double bonds
What is the geometry arrangement, Shape, angle and an example of something with:
2 Electron Pairs
0 Nonbonding Pairs
Example: BeCl2
Shape: Linear
Angle: 180 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
3 Electron Pairs
0 Nonbonding Pairs
Example: BH3
Shape: Trigonal Planar
Angle: 120 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
0 Nonbonding Pairs
Example: CH4
Shape: Tetrahedral
Angle: 109.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
1 Nonbonding Pairs
Example: NH3
Shape: Trigonal Pyramidal
Angle: 107.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
2 Nonbonding Pairs
Example: H2O
Shape: Bent
Angle: 104.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
5 Electron Pairs
0 Nonbonding Pairs
Example: PCl5
Shape: Trigonal Bipyramidal
Angle: 180, 120, 90 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
6 Electron Pairs
0 Nonbonding Pairs
Example: SF6
Shape: Octahedral
Angle: 180, 90 Deg
What are the types of intermolecular forces, list in decreasing strength
Result of electrostatic interactions between charges or partial charges on different molecules
- Ion-dipole
- Hydrogen
- Dipole-Dipole
- Dipole-Induced dipole (Debye)
- Induced dipoles only (LDF)
What does the principle number (n) tell you?
The rows on the periodic table
Higher energy level= larger radius
What does the angular (l) tell you?
Specifies the subshell within the principal energy level value can be any integer from 0 to (n-1)
0=s , 1=p , 2=d , 3=f
What does the magnetic (ml) tell you?
Specifies the orbital within the subshell
Possible values range from -L to L
eg. p orbital has ml values of -1, 0, 1
What does the spin (ms) tell you?
Can be either -1/2 or 1/2 and denotes inherent spin
Electrons in the same orbital must have opposit spin signs
What is Hund’s Rule?
Electrons fill into a subshell such that there are a maximum number of half-filled, parallel spin orbitals
(like a movie theater where you leave a space open between people that are not known)
What is Aufbau’s Principle?
Electrons fill accoruding to the (n+L) rule such that the subshell that has the smallest sum with the smallest n fills first
Explain the isotope notation
A = Atomic weight (mass) = Protons + Neutrons
Z = Atomic Number = # of protons
( ) = Charge (if present)
How is the periodic table arranged?
By number of protons
What are Alkali metals?
First column on the periodic table
Form +1 cations; highly reactive
(e.g. Na)
What are alkali earth metals?
Second column on the periodic table
Form +2 cations; Somewhat
(e.g. Ca)
What is the Carbon Family?
IVA group with 4 valence e-
Not easily ionizable; mix of properties
(e.g. Si)
What is the Nitrogen Family?
VA group with 5 valence e-
Not easily ionizable; mix of properties
(e.g. P)
What is the Oxygen Family?
VIA group with 6 valence e-
Form -2 anions; somewhat reactive
(e.g. F)
What are Halgens?
VIIA group with 7 valence e-
Form -1 anions; highly reactive
(e.g. F)
What are Noble Gases?
VIII A Group
Do not form ions or react
(e.g. Ne)
Describe the metals group on the periodic table
Group I and II especially. Form cations. Ductile, malleable, shiny, conductive
Describe the Transition metal group on the periodic table
d-block. may be able to form multiple cations and are colored when in ionic form. Particularly hard metals with high melting and boiling points
What are nonmetals on the periodic table?
Groups VI, VII and VIII especially form anions.
Brittle, poor conductors
What are Metalloids/ Semimetals on the periodic Table?
Lower left p-block also known as staircase.
Mixed properties, so specific characteristics are rarely tested
What is the effective Nuclear Charge (Zeff) and what is the trend on the periodic table?
The net positive charge a valence electron feels from the nucleus
- More positive nucleus: Higher Zeff
- More e- shielding: lower Zeff
What is the atomic radius and what is the trend?
Size of the atom
(only one opposit of Zeff)
Increase Zeff = Decrease r
What is electronegativity and what is the periodic trend?
Degree of attraction an atom has for electrons in a chemical bond
Increase Zeff = Increase E-
What is Ionization Energy and what is the periodic trend?
Energy required to completely remove an electron from an atom
What is electron affinity and what is the periodic trend?
Energy released when an electron gets an atom
Increased Zeff = Increased EA
What is the difference between a compound and a molecule?
- Molecules are two or more atoms held together. (eg H2)
- Compounds require those elements to be different. (eg H20)
What is the difference between Molecular Mass vs. Molar Mass?
- Molecular mass is the weight of one molecule in Daltons (Da or u)
- Molar mass is the weight of one mole of molecules in grams
- 1 mole = 6 x 10^23 entities
- 1 mole x 1 u = 1 gram
What is the difference between Empirical and Molecular Formulas?
- Empirical formulas use the smallest whole number ratio of atoms (eg. CH2O)
- Molecular formulas use the actual number of atoms (eg. C6H12O6)
How do you calculate the percent composition?
Percentage of mass contributed by each element in a compound
% composition = (Mass of X in formula) / (Formula weight of compound)
Describe the steps for balancing a reaction
See attached
What are limiting reactants?
The reactant completely consumed first, halting the forward reaction
What is the Stoichiometric Ratio?
Optimum ratios of moles of reactants such that all reactants are consumed.
Calculate ratios by dividing moles available by coefficients in balanced reactions
What is the theoretical yield?
The maximum yield calculated
What is the actual yield?
The experimental yield actually measured
How do you calculate the percent yield?
% Yield = (Actual Yield) / (Theoretical Yield) x 100
What is Enthalpy?
Delta H
The total heat content (energy) of a system
Describe an exothermic reaction
Heat given off
Lower potential energy in the products
Negative (-) Delta H
Describe an exothermic reaction
Heat taken in
Higher Potential Energy in products
Positive (+) delta H
What is the equation for the transfer of heat?
Delta U = Q - Wby system
Where:
Delta U = Change in internal energy
Q = Heat transferred
W = Work done by the system
Often seen as:
Wby = -Won
Name and describe the way that heat can be transfered
- Radiation = transfer of heat by eectromagnetic waves
- Conduction = Transfer of heat through direct contact
- Convection = Transfer of heat through bulk motion
What is the standard heat of fusion?
Delta H for the formation of 1 mole of substance
delta H = (sum of delta H products) - (sum of Delta H reactants)
Explain Hess’s Law
If a reaction can be broken down into a series of steps, the enthalpy change for the overall net reaction is the sum of the enthalpies of each step
Which bond is going to be more difficult to break:
N-H or O-H bond? Why?
O-H bond because it is it is more electronegative
What is entropy?
The disorder of a system; the energy of a system unable to do work
Gasses have the highest entropy
(Delta s)
Explain Gibbs Free energy. State the equation and explain results
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = - and dS = +
spontaneous or nonspontaneous?
Spontaneous = dG is negative
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = + and dS = -
spontaneous or nonspontaneous?
nonspontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = - and dS = - with low temperature
spontaneous or nonspontaneous?
spontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = + and dS = + with low temperature
spontaneous or nonspontaneous?
spontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
If frozen ice melts into liquid water, what sign is enthalpy and entropy?
Endothermic (heat input)
Enthalpy = Increases
Entropy = Increases
What is molecular equilibrium and how is it calculated?
Reaction Quotient (Q)
For a Reaction
aA + bB = cC + dD
Q = [products] / [reactants]
=( [C]c * [D]d ) / ( [A]a * [B]b ) = Keq
What is the equilibrium constant and compare it to Q?
Keq
Q < Keq Not yet reached equilibrium; rxn proceeds forward
Q = Keq at equilibrium; rate forward = rate reverse
Q > Keq Overshoot equilibrium; rxn proceeds in reverse
What is Le Chatelier’s Principle
If a stress (a change in concentration, pressure, or temperature) is applied to a system at equilibrium, the system will shift in such a way as to relieve the applied stress
If temperature increase is in the products, what does this mean?
Products = exothermic reaction
Reactants = Endothermic reaction
If pressure is increased,
what moles will be favoried (gas)?
what volume is favored?
Increased pressure means:
low moles favored (gas)
low volume favored
If pressure is decreased,
What moles and volume favored?
Pressure decreased favored
increased moles (gas)
increased volume