Mcat Genchem 1 Topical

Front 1

If Na has a first ioniozation energy of 496 kJ/mol, what is the frequency of light absorbed per photon in the photoionization of a gas phase Na sample?

Given: I = h*v
where I = ionization energy
h = Planck's constant (6.62 x 10^-34)
v = frequency

Back 1

Note: 496 kJ/mol (per mol of photons, not PER photon)

So for one photon, I = 496/6E23 = 8.24E-22kJ

Since I = hv, v= I/h=1.24E15 Hz

Front 2

Which of the following elements has the smallest atomic radius? Why?

K, Ca, Cs, Ba

Back 2

Radius increases as you go down a group and decreases as you go across a period, thus, the element at the uppermost right is smallest. This would be CALCIUM

Front 3

For transition elements, in what order will s and d orbitals fill?

Back 3

S will fill before D does, despite D being of lower energy.

Front 4

What are the ground state configurations of Fe++ and Fe+++?

Back 4

For neutral Fe: [Ar]3d64s2
REMEMBER: Fe is a transition metal, so the electrons in the s orbital are technically of higher energy and therefore are removed first.

So:
Fe++: [Ar]3d6
Fe+++: [Ar]3d5

Front 5

Given:
D = -I(A) + Ea(B)-(ZaZbe^2)/(4pi*epsilon naught)*R

Where D = Dissociation energy of a bond
I(A) = Ionization energy of atom A
Ea(B) = electron affinity of atom B
R = Distance between ions
and rest = Coulombia potentital energy

At what point is it energetically favorable for Li & Cl to form Li+Cl-?

Back 5

Ionic bond forms if D> or = 0 because if D is (-) that means you're not putting in energy to break the bond. So it's breaking on its own. In order for the bond to be stable, D must be (+).