1 - Atomic Structures & Period Trends

What is the energy of photon formula relating to wavelength (λ), speed of light (c), and planck's constant (h)?
What about planck's constant (h) and frequency (f)?

E = hf = hc/λ

As energy (E) increase, frequency (f) increases/decreases? wavelength (λ) increases/decreases?

frequency increases
wavelength decreases

order of visible colors from LEAST to MOST energy?

(ROYGBV)
Red
Orange
Yellow
Green
Blue
Violet

order of EM spectrum waves from LEAST to MOST amount of light energy (E)?

radio wave, microwave, infrared (IR), ROYGBV, UV ray, x-ray, gamma ray

electron exists within 3D orbitals, with its energies quantized and related to its specific orbital

quantum model

how does electron energy increase in a quantum model shown? (2)

1. nrg increases with distance from nucleus
2. nrg increases with complexity of orbital shape

what are the 3 principles that describe the atomic structure of the quantum model?

1. pauli principle
2. aufbau principle
3. hund's rule

quantum principle stating that in an atom or molecule, no two electrons can have the same four electronic quantum numbers in an orbital. The 2 electrons must also have opposing spins (up/down)

pauli principle

quantum principle stating that electrons must be added/removed from the LOWEST nrg oribitals FIRST. And valence electrons are removed from the HIGHEST lvl orbital

aufbau principle

example of aufbau principle:

Na = 1s2 2s2 2p6 3s1
Na+ (1 e- removed) = 1s2 2s2 2p6

quantum principle stating how electrons are added/removed in the same level. Electrons fill ALL orbitals 1st (up spin), then fill in the 2nd time (down spin) -- describes paramagnetic/diamagnetic configuration

hund's rule (spread out before doubling up)

atoms with unpaired electrons and are attracted by a magnetic field

paramagnetic atoms

atoms with all paired electrons and are NOT attracted by a magnetic field

diamagnetic atoms

[Ar] 4s1 3d5, NOT [Ar] 4s2 3d4
d/t Hund's rule, atoms prefer to spread out e-. Therefore, electron in 4s moves DOWN to 3d to fill for the last orbital.

what is Cr electron configuration? Why?

the electrons in the s orbital moves to d9 to fill it in completely. ex: Ag = 5s2 4d9 = 5s1 4d10

For electrons in the (n)s^2 (m)d4 and (m)d9 rows, what happens?

d/t hund's rule, e- in the ns^2 will be removed FIRST bc they're the HIGHEST nrg orbital
ex: Fe = [Ar] 4s2 3d6; Fe(II) = [Ar] 3d6

For electrons in the (n)s^2 (m)d4 OR (m)d9 rows, what happens if it becomes a cation? (1 electron removed)

D.
W = [Xe] 6s2 4d14 5d4 does NOT have a half-filled d orbital bc it's HEAVIER therefore other factors contribute to the stability of its ground state e- configurations.

which of the following transition metal elements does NOT have a half-filled d-orbital?
A. Mn
B. Tc
C. Cr
D. W

D.
NaNO3 = 23 + 16(3) + 14 = 85 g/mol
Na: 23/85 = >20%
N: 14/85 = <20%
O = 48/85 = >50%

What is the approximate percentage composition by mass of NaNO3?
A. 33% Sodium, 33% nitrogen, 34% oxygen
B. 20% Sodium, 20% nitrogen, 60% oxygen
C. 23% Sodium, 28% nitrogen, 49% oxygen
D. 27% Sodium, 16% nitrogen, 57% oxygen

A.
WO3 + H2 -> H2O + W
balanced: WO3 + 3H2 -> 3H2O + W

When heated, tungsten(VI) oxide, WO3, reacts with hydrogen gas to produce metallic tungsten and water vapor. Assuming that the reaction goes to completion, how many moles of solid tungsten are produced for every mole of hydrogen gas consumed?
A. 1/3
B. 2
C. 2/3
D. 3

D.
pretend there is 100g of compound.
64g is Ag, 8g is N, & 28% is O.
64g Ag / 108g/mol = 0.6mol
8g N / 14g/mol = 0.6mol
28g O / 16g/mol = 1.8mol
AgNO = 1:1:3 = AgNO3

A compound is found to contain 64% silver, 8% nitrogen, and 28% oxygen by mass. What is the empirical formula of this compound?

A. Ag3NO
B. Ag3NO3
C. AgNO2
D. AgNO3

D.
M = mol/L
50 cm^3 = 50 mL = .05L
0.5 mol / .05L = (5/10)(100/5) = 10M

What is the molar concentration of a solution containing 0.5 mol of solute in 50 cm3 of solution?

A. 1 M
B. 2 M
C. 0.1 M
D. 10 M

D.
(CV)1 + (CV)2 = (CV)final - formula used for DILUTION problems.

(15mL)(.02M CaCl2) + (10mL)(.04M CaSO4) = C(10+15mL)

What is the molar concentration of Ca2+(aq) in a solution that is prepared by mixing 15 mL of a 0.02 M CaCl2(aq) solution with 10 mL of a 0.04 M CaSO4(aq) solution?

A. 0.028 M Correct Answer
B. 0.035 M
C. 0.014 M
D. 0.020 M

A.
O is 2-(3) = -6
Fe must be 2(+3) = +^ to counter balance
Fe(III) = [Ar] 3d5

Which of the following is the correct electron configuration for the iron ions present in rust, Fe2O3?

A. [Ar] 3d5
B. [Ar] 4s23d3
C. [Ar] 4s23d4
D. [Ar] 3d6

C.
Reactivity of metallic elements increases down a column of the periodic table. This increase in reactivity corresponds with increased shielding from inner electron shells, increased atomic radius, and decreased ionization energy.

What is the reactivity, as indicated by the tendency to lose an electron, of sodium compared to potassium?

A. This cannot be determined from the information given.
B. Potassium has a lower reactivity because potassium has more protons than sodium.
C. Potassium has a higher reactivity because the valence electron on potassium is farther from the nucleus. Correct Answer
D. Both metals have the same reactivity because the potassium and sodium valence electrons experience the same effective nuclear charge.

B.
Even though S2- & Ar have same # of e-, Ar has more protons, which draws in the electrons more, thus decreasing its radius.

Rank the following atoms/ions in order of increasing atomic/ionic radius:
I. Ne
II. Ar
III. S2-
IV. Cs+

A. I < IV < II < III
B. I < II < III < IV
C. III < II < I < IV
D. IV < I < II < III

D.
ROYGBV (increasing nrg).

red = lowest nrg = n = 4 -> 3 bc that has the least nrg
yellow = 2nd lowest nrg = n = 3 -> 2
blue = highest nrg = n = 2 -> 1 bc that has the most nrg since it's the closest to nucleus

Which of the following electron transitions (between energy levels, labeled by n) could account for the emission of photons of red, yellow, and blue light from a pure noble gas?

A. n = 4 to n = 1, n = 4 to n = 2, and n = 4 to n = 3, respectively
B. n = 1 to n = 0, n = 2 to n = 1, and n = 3 to n = 2, respectively
C.n = 2 to n = 1, n = 3 to n = 2, and n = 4 to n = 3, respectively Your Answer
D. n = 4 to n = 3, n = 3 to n = 2, and n = 2 to n = 1, respectively

A.

The reactivity of alkali metals follows the trend Cs > Rb > K > Na > Li. Which of the following is the best explanation for this trend?

A. The ionization energy increases from Cs to Li.
B. The electron affinity increases from Li to Cs.
C. The electronegativity decreases from Cs to Li.
D. The atomic size decreases from Li to Cs.

D.
ionization energy is the amount of energy required to REMOVE an e- from an atom

Which of the following is true of ionization energy?

A. It increases with period, and the second ionization energy is greater than the first.
B. It decreases with period, and the first ionization energy is greater than the second.
C. It increases with period, and the first ionization energy is greater than the second.
D. It decreases with period, and the second ionization energy is greater than the first.

B.

Which of the following could be the electron configuration of a boron atom in an excited state?

A. 1s2 2s2 2p1
B. 1s2 2s1 2p2
C. 1s2 2s1 2p1
D. 1s2 2s2 2p2

D.

Which of the following is true of an electron in an excited state?

A. It has absorbed a photon, and its energy has decreased.
B. It has emitted a photon, and its energy has increased. Your Answer
C. It has emitted a photon, and its energy has decreased.
D. It has absorbed a photon, and its energy has increased.

D.

Octahedral compounds have six σ bonds and no stereochemically active lone pairs. According to valence bond theory, the central atom requires the hybridization of six atomic orbitals, d²sp³.

Which of the following types of orbitals of the central atom are involved in bonding in octahedral compounds?

A. sp

B. sp3

C. p

D. d2 sp3

A.

proton emission = beta-plus decay
neutron emission = nuclear fission
electron emission = beta-minus decay

gamma decay occurs when nucleus emits:

A. a photon

B. a proton

C. a neutron

D. an electron