Chem 010 exam 2

law of conservation of energy

energy cannot be created or destroyed

heat (q)

transfer of energy btwn two bodies at different temperatures (goes hot to cold)

endothermic

absorbs heat

q_sys > 0

exothermic

releases heat

q_sys < 0

heat capacity

C = q/∆T

specific heat capacity

C = q/m∆T

calorimetry

q_system = -q_surroundings

internal energy (U)

total of all possible kind of energy in a substance

internal energy equation

∆U = q + w

work formula

-W = P∆V

enthalpy (∆H)

∆H = ∆U + P∆V

∆H = q_p

what does enthalpy depend on

physical state!

enthalpy of exothermic reaction

∆H < 0

enthalpy of endothermic reaction

∆H > 0

Hess’s Law

if process can be written as a sum of several steps, enthalpy is the sum of the enthalpies during those steps

hess’s law equation

∆rH°=∑n(∆H_f°products) - ∑n(∆H_f°reactants)

waves

oscillation/periodic movement that can transport energy from one space to another

wavelength (λ)

distance btwn two peaks in a wave

frequency (v)

number of wave cycles that pass a specified point in space and time

speed of light equation

c = λv

nodes

points on the string btwn end points that are not moving

de brogile wavelength (where h is plak’s constant)

λ = h/mv

uncertainty principle

(∆x)(m∆v) >/= h/4π

atomic orbital

general region in atom where e- is most probable to reside

quantum #’s

n, l, m_l, m_s

quantum number: n

principal quantum number / shell number

general size and energy

= 1, 2, 3, …

quantum number: l

angular momentum number (shape of orbial and subshell)

= 0 ,1, 2, … n-1

l = 0

s

l=1

p

l=2

d

l=3

f

quantum number m_l

magnetic quantum number

(spacial orientation, total number of possible orbitals)

= -l, -(l-1), 0, l-1, 1

quantum number: m_s

direction of e- spin

= ½ or -1/2

hund’s rule

lowest energy configuration w/in set of degenerate orbitals is having max number of unpaired e-

pauli’s exclusion principle

no two e- in same atom can have exact same quantum numbers

• m_s must be different

aufbau principle

e- enter higher energy subshells only after low energy subshells have been filled to capacity

shape n=s (l=0)

one bubble

shape of n=p (l=1)

two bubbles

shape of n=d (l=2)

four bubbles

shape of n=f (l=3)

six bubbles

variation in covalent radius

• when going down columns/groups, n increases

• largest in bottom left corner

effective nuclear charge

Z_eff = Z - shielding

Z_eff

• increases across periods

• nuclear charge minus how well inner e- shield outer e-

ionization energy

energy needed to remove 2nd most loosely bound e-

ionization energy equation

X⁺ (g) —> X²⁺ (g) + e-

electron affinity (EA1)

energy associated with adding e- to a gaseous atom to from an anion

EA1 equation

X (g) + e- —> X^-(g)

endothermic electron affinity

+EA

exothermic electron affinity

-EA