Chemistry - Final Study Guide

Given the following data, what is the energy change for this reaction?

(might b wrong) +146.8 kJ mol-1

Use the following data reactions: calculate the energy of an H-Cl bond

(might b wrong) 428 kJ

In the photoelectric effect, the frequency of light will

(might b wrong) b and c

Calculate the lattice energy for LiF(s) given the following: Sublimation energy for Li(s) +161 kJ/mol ΔHf for F(g) +77 kJ/mol First ionization energy of Li(g) +520. kJ/mol Electron affinity of F(g) -328 kJ/mol Enthalpy of formation of LiF(s) -617 kJ/mol

-1047 kJ/mol

How many electrons can be described by the quantum numbers n = 3, l = 3, ml = 1?

0

How many electrons can be described by the quantum numbers n = 4, l = 4, ml = 1?

0

How many electrons can be described by the quantum numbers n = 6, l = 2, ml = 1, ms = 1?

0

How many f orbitals have the value n = 3?

0

Consider the compound crotonaldehyde, whose skeleton is Which carbon in this molecule has tetrahedral bonding?

1

Consider the following portion of the energy-level diagram for hydrogen: n = 4 -0.1361 × 10-18 J n = 3 -0.2420 × 10-18 J n = 2 -0.5445 × 10-18 J n = 1 -2.178 × 10-18 J In the hydrogen spectrum, what is the wavelength of light associated with then= 2 ton= 1 electron transition?

1.216 × 10-7 m

A photographic film needs a minimum of 80.0 kJ/mol for exposure. What is the longest wavelength of radiation with sufficient energy to expose the film?

1.50 × 10-6 m

The wavelength of light associated with the n = 2 to n = 1 electron transition in the hydrogen spectrum is 1.216 × 10-7 m. By what coefficient should this wavelength be multiplied to obtain the wavelength associated with the same electron transition in the Li2+ ion?

1/9

How many electrons in an atom can have the quantum numbers n = 5, l = 2?

10

For an electron in a 2.00-nm one-dimensional box, calculate the wavelength of electromagnetic radiation to excite the electron from the ground state to the level with n = 3.

1650 nm

Consider the following portion of the energy-level diagram for hydrogen: n = 4 -0.1361 × 10-18 J n = 3 -0.2420 × 10-18 J n = 2 -0.5445 × 10-18 J n = 1 -2.178 × 10-18 J On a planet where the temperature is so high, the ground state of an electron in the hydrogen atom isn= 4. What is the ratio of IE on this planet to that on earth?

1:16

How many electrons can be described by the quantum numbers n = 4, l = 3, ml = 0?

2

How many of the following electron configurations for the species in their ground state are correct? Ca: 1s22s22p63s23p64s2 Mg 1s22s22p63s1 V [Ar}3s23d3 As [Ar]4s23d104p3 P 1s22s22p63p5

2

How many of the following molecules and ions are linear? NCl3 CH4 SCN- CS2 NO2-

2

How many unpaired electrons are there in an atom of sulfur in its ground state?

2

How many unpaired electrons does nickel have in its ground state?

2

How many valence electrons do the alkaline earth metals have?

2

The first ionization energy of Mg is 735 kJ/mol. Calculate Zeff.

2.25

How many electrons are in the Lewis structure for SO3?

24

What is the probability of finding a particle in a one-dimensional box in energy level n = 4 between x = L/4 and x = L/2? (L is the length of the box.)

25%

The number of orbitals having a given value of l is equal to

2l + 1

How many unpaired electrons does arsenic have in its ground state?

3

Light has a wavelength of 6.4 × 102 nm. What is the energy of a photon of this light?

3.10 × 10-19 J

An electron in a one-dimensional box requires energy with wavelength 8080 nm to excite it from the n = 2 energy level to the n = 3 energy level. Calculate the length of the box.

3.50 nm

For an electron in a one-dimensional box, what is the minimum energy to excite the electron from the ground state?

3h^2/8mL^2

What is the valence electron configuration of S?

3s23p4

An atom of oxygen contains 8 electrons. How many of these electrons are in p orbitals?

4

What is the wavelength of light that is emitted when an excited electron in the hydrogen atom falls from the n = 5 level to the n = 2 level?

4.34 × 10-7 m

The ionization energy for a hydrogen atom is 1.31 × 106 J/mol. What is the ionization energy for He+?

5.25 × 106 J/mol

What is the wavelength, in nanometers, of a photon of light whose frequency is 5.24 × 1014 Hz?

5.72 × 102 nm

What is the total number of electrons that can be accommodated in the level corresponding to n = 5?

50

For a particle in a cubic box, how many degenerate energy levels have energy equal to 14 h2/8 mL2?

6

How many electrons can be described by the quantum numbers n = 3, l = 1?

6

Which of the following statements is false?

A 2p orbital is more penetrating than a 2s; that is, it has a higher electron density near the nucleus and inside the charge cloud of a 1s orbital.

The energy equation for a particle in a cubic box of dimensions Lx = Ly = Lz is Enx, ny, nz = Assume that 8 electrons occupy the allowed energy levels and that 2 electrons can occupy each allowed energy level. A. In the ground state, how many of the 8 electrons have energy equal to ? B. In the ground state, how many of the 8 electrons have energy equal to ? C. In the ground state, how many of the 8 electrons have energy equal to ? D. Calculate the wavelength of light necessary to promote the highest-energy ground-state electron into the lowest-energy excited state. Assume a cubic box with dimensions 1.50 nm × 1.50 nm × 1.50 nm.

A. 2 B. 6 C. 0 D. 2470 nm

Of the following elements, which needs 3 electrons to complete its valence shell?

As

Which of the following groups contains no ionic compounds?

CH2O, H2O, NBr3

Use the following electronegativity values to answer the question: C 2.5 Cl 3.2 H 2.2 N 3.0 O 3.4 This molecule contains a carbon atom with trigonal planar geometry.

CH3CHO

As indicated by Lewis structures, which of the following would probably not exist as a stable molecule?

CH3O

Which ion is planar?

CO32-

Consider an atom traveling at 1% of the speed of light. The de Broglie wavelength is found to be 3.31 × 10-3 pm. Which element is this?

Ca

Rank from smallest to largest in terms of atomic ionic radii.

Ca2+, K+, Ar, Cl-, S2-

Based on electronegativities, which of the following would you expect to be most ionic?

CaF2

Choose the molecule with the strongest bond.

Cl2

For which of the following elements does the electron configuration for the lowest energy state show a partially filled d orbital?

Cr

Which of the following sets has elements with the most nearly identical atomic radii?

Cr, Fe, Co, Mn

Identify the order that is observed experimentally for direct reactions between the solid alkali metals and nonmetals.

Cs > Rb > K > Na > Li

An element E has the electron configuration [Ar]3d104s24p3. What is the formula for the fluoride of E most likely to be?

EF3

Which of the following Lewis structures best describes BF3?

F (all dots) - B (no dots) - 2 Fs with all dots

Consider the following orderings. I. Al < Si < P < Cl II. Be < Mg < Ca < Sr III. I < Br < Cl < F IV. Na+ < Mg2+ < Al3+ < Si4+ Which of these give(s) a correct trend in ionization energy?

I, III, IV

Which statements about hydrogen are true? I. H has a lower ionization energy than He. II. H- is smaller than H. III. H has a lower effective nuclear charge than He. IV. H is always a metal. V. H does not have a second ionization energy.

I, III, V

Which molecule or ion violates the octet rule?

I3-

Consider the following orderings. I. Al < Si < P < ClII. Be < Mg < Ca < SrIII. I < Br < Cl < FIV. Na+ < Mg2+ < Al3+ < Si4+ Which of these give(s) a correct trend in size?

II only

The energy expressions for the electrons in the He+ ion and the hydrogen atom are En (H) = -a/n2 and En (He+) = -4a/n2Which of the following statements is(are) correct? I.For the transitions n1 → n2 , the frequency of electromagnetic radiation required is larger for H than for He+.II.The first ionization energy of the H atom is smaller than the second ionization energy of the He atom.III.The 1s orbital in He+ is larger (in the sense that the probability density is shifted outward) than the 1s orbital in H.

II only

Which of the following statements is(are) true? I. An excited atom can return to its ground state by absorbing electromagnetic radiation. II. The energy of an atom is increased when electromagnetic radiation is emitted from it. III. The energy of electromagnetic radiation increases as its frequency increases.IV. An electron in the n = 4 state in the hydrogen atom can go to the n = 2 state by emitting electromagnetic radiation at the appropriate frequency. V. The frequency and wavelength of electromagnetic radiation are inversely proportional to each other.

III, IV, V

Which of the following is a reasonable criticism of the Bohr model of the atom?

It does not adequately predict the ionization energy of the valence electron(s) for elements other than hydrogen.

Choose the compound with the most ionic bond. KCl LiCl NaCl KF RbI

KF

Which atom has three 2p electrons in its ground state?

N

As indicated by Lewis structures, which of the following species could probably not exist as a stable molecule?

N2H6

Which of the following compounds contains only one unshared pair of valence electrons?

NH3

Which of the following has the Lewis structure most like that of CO32-?

NO3-

Which element has the greatest second ionization energy?

Na

Place the elements Ge, S, and Ne in order of increasing atomic radius.

Ne, S, Ge

Researchers recently formed a new synthetic element with atomic number 110. Which of the following elements would have chemical properties most similar to this new element?

Ni

What is the electron arrangement around the central atom of XeF4?

Octahedral

Which of the following is polar?

PBr3

Which of the following molecules has a dipole moment? none of these BCl3 SiCl4 Cl2 PCl3

PCl3

The molecule XCl5- has a square pyramidal shape. Which of the following atoms could be X?

S

Which of the following series is isoelectronic?

S2-, Cl-, K+, Ca2+

Which of the following molecules has a dipole moment? None of these has a dipole moment. CF4 XeF4 SF4 All of these have a dipole moment.

SF4

Which of the following has the smallest radius? Sr2+ Se2- Rb+ Br+ Kr

Sr2+

Which of the following statements is true of second ionization energies?

That of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton.

A quantum chemistry program indicates that the dipole moment of PH3 is zero. Which statement(s) best explains this result?

The electronegativities of P and H are very close in value; therefore, no bond dipoles exist.

Which statement is correct?

The molecule ClO2 cannot be accurately described by a Lewis structure consistent with the octet rule.

What is the electron configuration for Cr2+?

[Ar] 3d4

What is the electron configuration for the chromium atom?

[Ar] 4s13d5

What is the electron configuration of the element with atomic number 113?

[Rn] 7s25f146d107p1

What is the electron configuration for the barium atom?

[Xe] 6s2

Select the correct molecular structure for SO2.

bent

From the following list of observations, choose the one that most clearly supports the conclusion that electromagnetic radiation has wave characteristics.

diffraction

In Bohr's atomic theory, when an electron moves from one energy level to another energy level more distant from the nucleus,

energy is absorbed.

Which form of electromagnetic radiation has the shortest wavelengths?

gamma rays

The _____ is defined as the change in energy that takes place when separated gaseous ions are packed together to form an ionic solid.

lattice energy

An element has the electron configuration [Kr] 4d105s25p2. The element is a(n)

metal

Consider the following portion of the energy-level diagram for hydrogen: n = 4 -0.1361 × 10-18 J n = 3 -0.2420 × 10-18 J n = 2 -0.5445 × 10-18 J n = 1 -2.178 × 10-18 J For which of the following transitions does the light emitted have the lowest frequency?

n = 4 to n = 3

An electron in a 10.0-nm one-dimensional box is excited from the ground state into a higher energy state by absorbing a photon with wavelength 1.374 × 10-5 m. Determine the final energy level for this transition.

n = 5

Select the correct molecular structure for SF5+.

none of these

Select the correct molecular structure for PF3.

pyramidal

The Lewis structure for H3BO3 is

single bonds for everything, O has 2 lone pairs around them and B has no lone pairs

In an investigation of the electronic absorption spectrum of a particular element, it is found that a photon having λ = 500 nm provides just enough energy to promote an electron from the second quantum level to the third. From this information, we can deduce

the difference between the energies of the n = 2 and n = 3 levels.

From the following list of observations, choose the one that most clearly supports the conclusion that electrons in atoms have quantized energies.

the emission spectrum of hydrogen

According to the VSEPR model, the electron pairs around NH3 and those around CH4 are arranged

the same, because in each case there are the same number of electron pairs around the central atom.

From the following list of observations, choose the one that most clearly supports the conclusion that the mass of the atom is located mainly in the nucleus.

the scattering of alpha particles by metal foil

Which of the following is not determined by the principal quantum number, n, of the electron in a hydrogen atom?

the shape of the corresponding atomic orbital(s)

The _____ states that in a given atom no two electrons can have the same set of four quantum numbers (n, l, ml, ms).

​Pauli exclusion principle

The distance between the centers of the Li+ and F− ions is 156 pm. Determine the energy of interaction between the pair of ions for a mole of Li+ and F− ions.

−892 kJ/mol