Thermochemistry
In an exothermic reaction: is delta H negative or positive?
positive
Does an increase in Temperature increase or decrease the rate of reaction?
Increase; molecules collide more often
Do molecules with higher atomic numbers have smaller or larger atomic radii?
Smaller
What is electronegativity?
A number that indicates how strongly the nucleus of a particular atom attracts the valence electrons of other atoms
What is entropy?
A measure of the number of possible microstates of a substance
If a gas expands (volume increases): is work positive or negative?
negative (system does work on the surroundings)
What is activation energy?
Minimum amount of energy required for a reaction to occur
What is hybridization?
When atoms bond with other atoms, the first mix with their atomic orbitals to form hybrid orbitals, these hybrid orbitals overlap with other orbitals
In a polar covalent bond: are the electrons shared evenly or unevenly between the two atoms?
Unevenly
How do Temperature, volume, and state of matter affect the entropy of a substance?
Temperature: when temperature increases, entropy increases
Volume: when volume increases, entropy increases
States of matter: solid--> liquid --> gas, entropy increases
Does the temperature of the surroundings increase or decrease in an endothermic reaction?
decrease
What is a catalyst?
A chemical added to speed up the reaction (not a reactant or product)
What is ionization energy?
How many valence electrons does each atom (except H) get in a lewis dot structure?
8 (H gets 2)
What is a spontaneous reaction?
A reaction which will shift right (produces products) from an initial set of conditions?
If you flip a reaction (using Hess's law), what happens to delta H?
The sign changes
What does "order" mean in a rate law?
An exponent ([A]^x)
Do electrons in higher subshells have higher or lower ionization energies?
lower (weaker attraction to the nucleus bc they are further away)
What is the ideal formal charge of each atom in a lewis dot structure?
zero
What is the second law of thermodynamics?
In any spontaneous change, the entropy of the universe (system+ surroundings) increases
What is standard state of a substance?
1 atm (gas), 1 M (aqueous)
What affects the rate constant (k) of a reaction?
The temperature and presence of a catalyst
When an electron changes energy levels and moves closer to the nucleus, the energy lost is in what form?
A photon of light
Place in order of strength (strongest to weakest): hydrogen bonding, dipole-dipole forces, london dispersion forces, covalent bonding
Covalent bonding, hydrogen bonding, dipole-dipole
LDFs are weaker than covalent, but can be weaker or strong than H-bonding or dipole-dipole, depending on the number of electrons
How is the spontaneity of a reaction related to the sign of change in free energy?
Negative change in free energy= spontaneous reaction