Questions and Answers of Chemistry The Central Science

Shown here are three pairs of hybrid orbitals, with each set at a characteristic angle. For each pair, determine the type of hybridization, if any, that could lead to hybridorbitals at the specified
(a) Consider the AF3 molecules in Exercise 9.27. Which of these will have a nonzero dipole moment?(b) Which of the AF4 molecules in Exercise 9.28 will have a zero dipole moment?
The following is part of a molecular orbital energy-level diagram for MOs constructed from 1s atomic orbitals.(a) What labels do we use for the two MOs shown?(b) For which of the following molecules
The molecule shown below is called furan. It is represented in typical shorthand way for organic molecules, with hydrogen atoms not shown.(a) What is the molecular formula for furan?(b) How many
The drawing below shows the overlap of two hybrid orbitals to form a bond in a hydrocarbon. (a) Which of the following types of bonds is being formed: (i) C—C s, (ii) C—C p
Silicon, the element, is the heart of integrated circuits and computer chips in almost all of our electronic devices. Si has the same structure as diamond; each atom is singly bonded to four
The compound chloral hydrate, known in detective stories as knockout drops, is composed of 14.52% C, 1.83% H, 64.30% Cl, and 13.35% O by mass, and has a molar mass of 165.4 g/mol.(a) What is the
Consider the hypothetical molecule B—A=B. Are the following statements true or false?(a) This molecule cannot exist.(b) If resonance was important, the molecule would have identical A–B bond
Although I3- is known, F3- is not. Which statement is the most correct explanation?(a) Iodine is more likely to be electron-deficient.(b) Fluorine is too small to accommodate three nonbonding
A classmate of yours is convinced that he knows everything about electronegativity.(a) In the case of atoms X and Y having different electronegativities, he says, the diatomic molecule X—Y must be
Draw the dominant Lewis structures for these chlorine–oxygen molecules/ions: ClO, ClO-, ClO2-, ClO3-, ClO4-. Which of these do not obey the octet rule?
Fill in the blank with the appropriate numbers for both electrons and bonds (considering that single bonds are counted as one, double bonds as two, and triple bonds as three).(a) Fluorine has ____
Indicate whether each statement is true or false:(a) The octet rule is based on the fact that filling in all s and p valence electrons in a shell gives eight electrons.(b) The Si in SiH4 does not
(a) Do the C—C bond lengths in benzene alternate shortlong-short-long around the ring? Why or why not?(b) Are C—C bond lengths in benzene shorter than C—C single bonds?(c) Are C—C bond
Which one of these statements about formal charge is true?(a) Formal charge is the same as oxidation number.(b) To draw the best Lewis structure, you should minimize formal charge.(c) Formal charge
Which of the following statements about electronegativity is false?(a) Electronegativity is the ability of an atom in a molecule to attract electron density toward itself.(b) Electronegativity is the
(a) Construct a Lewis structure for O2 in which each atom achieves an octet of electrons.(b) How many bonding electrons are in the structure?(c) Would you expect the O—O bond in O2 to be shorter or
(a) State whether the bonding in each compound is likely to be covalent or not: (i) iron, (ii) sodium chloride, (iii) water, (iv) oxygen, (v) argon.(b) A substance XY, formed from two different
Consider the ionic compounds KF, NaCl, NaBr, and LiCl.(a) Use ionic radii (Figure 7.8) to estimate the cation–anion distance for each compound.(b) Based on your answer to part (a), arrange these
The ionic substances NaF, CaO, and ScN are isoelectronic (they have the same number of electrons). Examine the lattice energies for these substances in Table 8.2. Make a graph of lattice energy on
(a) Is lattice energy usually endothermic or exothermic?(b) Write the chemical equation that represents the process of lattice energy for the case of NaCl.(c) Would you expect salts like NaCl, which
(a) Use Lewis symbols to represent the reaction that occurs between Ca and F atoms.(b) What is the chemical formula of the most likely product?(c) How many electrons are transferred?(d) Which atom
Consider the element silicon, Si.(a) Write its electron configuration.(b) How many valence electrons does a silicon atom have?(c) Which subshells hold the valence electrons?
(a) True or false: An element’s number of valence electrons is the same as its atomic number.(b) How many valence electrons does a nitrogen atom possess?(c) An atom has the electron configuration
A portion of a two-dimensional “slab” of NaCl(s) is shown here (see Figure 8.3) in which the ions are numbered.(a) Which colored balls must represent sodium ions?(b) Which colored balls must
Elemental cesium reacts more violently with water than does elemental sodium. Which of the following best explains this difference in reactivity?(i) Sodium has greater metallic character than does
Which of the following is the expected product of the reaction of K(s) and H2(g)?(i) KH(s)(ii) K2H(s)(iii) KH2(s)(iv) K2H2(s)(v) K(s) and H2(g) will not react with one another.
Which of the following chemical equations is connected to the definitions of:(a) The first ionization energy of oxygen.(b) The second ionization energy of oxygen.(c) The electron affinity of
The following observations are made about two hypothetical elements A and B: The A—A and B—B bond lengths in elemental A and B are 2.36 and 1.94 Å, respectively. A and B react to form the binary
The As—As bond length in elemental arsenic is 2.48 Å. The Cl—Cl bond length in Cl2 is 1.99 Å.(a) Based on these data, what is the predicted As—Cl bond length in arsenic trichloride, AsCl3, in
In Table 7.8, the bonding atomic radius of neon is listed as 0.58 Å, whereas that for xenon is listed as 1.40 Å. A classmate of yours states that the value for Xe is more realistic than the one for
Figure 7.4 shows the radial probability distribution functions for the 2s orbitals and 2p orbitals.(a) Which orbital, 2s or 2p, has more electron density close to the nucleus?(b) How would you modify
Potassium and hydrogen react to form the ionic compound potassium hydride.(a) Write a balanced equation for this reaction.(b) Use data in Figures 7.10 and 7.12 to determine the energy change in
You read the following statement about two elements X and Y: One of the elements is a good conductor of electricity, and the other is a semiconductor. Experiments show that the first ionization
(a) Does metallic character increase, decrease, or remain unchanged as one goes from left to right across a row of the periodic table?(b) Does metallic character increase, decrease, or remain
Consider the following equation:Ca+(g) + e-→Ca(g)Which of the following statements are true?(i) The energy change for this process is the electron affinity of the Ca+ ion.(ii) The energy change for
Write the electron configurations for the following ions, and determine which have noble-gas configurations:(a) Ru3+(b) As3-(c) Y3+(d) Pd2+(e) Pb2+(f) Au3+
Write the electron configurations for the following ions, and determine which have noble-gas configurations: (a) Co2+(b) Sn2+(c) Zr4+(d) Ag+(e) S2-
Using only the periodic table, arrange each set of atoms in order of increasing radius:(a) Ba, Ca, Na(b) Sn, Sb, As(c) Al, Be, Si.
Which of the following statements about the bonding atomic radii in Figure 7.7 is incorrect?(i) For a given period, the radii of the representative elements generally decrease from left to right
Which of the following statements about effective nuclear charge for the outermost valence electron of an atom is incorrect?(i) The effective nuclear charge can be thought of as the true nuclear
(a) Evaluate the express ions 2 × 1, 2 × (1 + 3), 2 × (1 + 3 + 5), and 2 × (1 + 3 + 5 + 7).(b) How do the atomic numbers of the noble gases relate to the numbers from part (a)?(c) What
(a) Which of the following charts below shows the general periodic trends for each of the following properties of the main-group elements (you can neglect small deviations going either across a row
Shown below is a qualitative diagram of the atomic orbital energies for an Na atom. The number of orbitals in each subshell is not shown.(a) Are all of the subshells for n = 1, n = 2, and n = 3
Consider the Mg2+, Cl-, K+, and Se2- ions. The four spheres below represent these four ions, scaled according to ionic size.(a) Without referring to Figure 7.8, match each ion to its appropriate
In August 2011, the Juno spacecraft was launched from Earth with the mission of orbiting Jupiter in 2016. The closest distance between Jupiter and Earth is 391 million miles.(a) If it takes 5.0 years
In the experiment shown schematically below, a beam of neutral atoms is passed through a magnetic field. Atoms that have unpaired electrons are deflected in different directions in the magnetic field
Using the periodic table as a guide, write the condensed electron configuration and determine the number of unpaired electrons for the ground state of (a) Br, (b) Ga, (c) Hf, (d)
Determine whether each of the following sets of quantum numbers for the hydrogen atom are valid. If a set is not valid, indicate which of the quantum numbers has a value that is not valid:(a) n = 4,
As discussed in the A Closer Look box on “Measurement and the Uncertainty Principle,” the essence of the uncertainty principle is that we can’t make a measurement without disturbing the system
An electron is accelerated through an electric potential to a kinetic energy of 13.4keV. What is its characteristic wavelength?Recall that the kinetic energy of a moving object is E = 12mv2, where m
Consider a transition in which the hydrogen atom is excited from n = 1 to n = ∞.(a) What is the end result of this transition?(b) What is the wavelength of light that must be absorbed to accomplish
In an experiment to study the photoelectric effect, a scientist measures the kinetic energy of ejected electrons as a function of the frequency of radiation hitting a metal surface. She obtains the
The following electron configurations represent excited states. Identify the element and write its ground-state condensed electron configuration.(a) 1s2 2s2 2p4
For each element, indicate the number of valence electrons, core electrons, and unpaired electrons in the ground state:(a) Nitrogen(b) Silicon(c) Chlorine.
What is the maximum number of electrons in an atom that can have the following quantum numbers?(a) n = 3, ml = -2(b) n = 4, l = 3(c) n = 5, l = 3, ml = 2(d) n = 4, l = 1, ml = 0.
The hydrogen atom can absorb light of wavelength 1094 nm.(a) In what region of the electromagnetic spectrum is this absorption found?(b) Determine the initial and final values of n associated with
The visible emission lines observed by Balmer all involved nf = 2.(a) Which of the following is the best explanation of why the lines with nf = 3 are not observed in the visible portion of the
Place the following transitions of the hydrogen atom in order from shortest to longest wavelength of the photon emitted: n = 5 to n = 3, n = 4 to n = 2, n = 7 to n = 4, and n = 3 to n = 2.
Order the following transitions in the hydrogen atom from smallest to largest frequency of light absorbed: n = 3 to n = 6, n = 4 to n = 9, n = 2 to n = 3, and n = 1 to n = 2.
Consider a transition of the electron in the hydrogen atom from n = 4 to n = 9.(a) Is ΔE for this process positive or negative?(b) Determine the wavelength of light that is associated with this
(a) Consider the following three statements: (i) A hydrogen atom in the n = 3 state can emit light at only two specific wavelengths, (ii) A hydrogen atom in the n = 2 state is at a lower
A laser pointer used in a lecture hall emits light at 650 nm. What is the frequency of this radiation? Using Figure 6.4, predict the color associated with this wavelength. Wavelength (m)- 10-9 10-11
The energy from radiation can be used to cause the rupture of chemical bonds. A minimum energy of 242 kJ/mol is required to break the chlorine–chlorine bond in Cl2. What is the longest wavelength
(a) A green laser pointer emits light with a wavelength of 532 nm. What is the frequency of this light?(b) What is theenergy of one of these photons?(c) The laser pointer emits light because
(a) Calculate the energy of a photon of electromagnetic radiation whose frequency is 2.94 × 1014 s-1.(b) Calculate the energy of a photon of radiation whose wavelength is 413 nm. (c) What
(a) What is the frequency of radiation whose wavelength is 0.86 nm?(b) What is the wavelength of radiation that has a frequency of 6.4 × 1011 s-1?(c) Would the radiations in part (a) or part (b) be
The accompanying drawing shows the shape of a d orbital.(a) Based on the shape, how many of the d orbitals could it be?(b) Which of the following would you need to determine which of the d orbitals
Stars do not all have the same temperature. The color of light emitted by stars is characteristic of the light emitted by hot objects. Telescopic photos of three stars are shown below: (i) the Sun,
We can use Hess’s law to calculate enthalpy changes that cannot be measured. One such reaction is the conversion of methane to ethylene:2CH4(g)→C2H4(g) + H2(g)Calculate the ΔH° for this
The air bags that provide protection in automobiles in the event of an accident expand because of a rapid chemical reaction. From the viewpoint of the chemical reactants as the system, what do you
At the end of 2012, global population was about 7.0 billion people. What mass of glucose in kg would be needed to provide 1500 cal/person/day of nourishment to the global population for one year?
Given the data:N2(g) + O2(g)→2NO(g) ΔH = +180.7 kJ2NO(g) + O2(g)→2NO2(g) ΔH = -113.1 kJ2N2O(g)→2N2(g) + O2(g) ΔH = -163.2 kJUse Hess’s law to calculate ΔH for the reactionN2O(g) +
Consider the data about gold metal in Exercise 5.26(b).Data from Exercise 5.26(b).A 100.0-g bar of gold is heated from 25 °C to 50 °C during which it absorbs 322 J of heat. Assume the volume of the
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates:Ag+(aq)+Cl-(aq)→AgCl(s) ΔH = -65.5 kJ(a) Calculate ΔH for the production of 0.450 mol of AgCl by
Consider the following reaction:2Mg(s) + O2(g)→2MgO(s) ΔH = -1204 kJ(a) Is this reaction exothermic or endothermic?(b) Calculate the amount of heat transferred when 3.55 g of Mg(s) reacts at
Assume that the following reaction occurs at constant pressure:2Al(s) + 3Cl2(g)→2 AlCl3(s)(a) If you are given ΔH for the reaction, what additional information do you need to determine ΔE for the
How much work (in J) is involved in a chemical reaction if the volume decreases from 5.00 to 1.26L against a constant pressure of 0.857 atm?
(a) State the Pauli exclusion principle in your own words.(b) The Pauli exclusion principle is, in an important sense, the key to understanding the periodic table.(c) Explain.
A hydrogen atom orbital has n = 5 and ml = -2.(a) What are the possible values of l for this orbital?(b) What are the possible values of ms for the orbital?
A certain orbital of the hydrogen atom has n = 4 and l = 2.(a) What are the possible values of ml for this orbital?(b) What are the possible values of ms for the orbital?
Neutron diffraction is an important technique for determining the structures of molecules. Calculate the velocity of a neutron needed to achieve a wavelength of 1.25 Å. (Refer to the inside cover
The electron microscope has been widely used to obtain highly magnified images of biological and other types of materials. When an electron is accelerated through a particular potential field, it
Titanium metal requires a photon with a minimum energy of 6.94 × 10-19 J to emit electrons.(a) What is the minimum frequency of light necessary to emit electrons from titanium via the photoelectric
Fill in the gaps in the following table, assuming each column represents a neutral atom. Symbol 112 Cd Protons 38 92 Neutrons 58 49 Electrons 38 36 Mass no. 81 235
Fill in the gaps in the following table: Symbol 31p)- Protons 34 50 Neutrons 45 69 118 Electrons 46 76 Net charge 2- 3+
The concept of chemical equilibrium is very important. Which one of the following statements is the most correct way to think about equilibrium?(a) If a system is at equilibrium, nothing is
Which data set, of the two graphed here, would you expect to observe from a titration like that shown in Figure 4.18? Highly colored No color 2 4 6 8. 10 12 mL standard solution Color from indicator
You are titrating an acidic solution with a basic one, and just realized you forgot to add the indicator that tells you when the equivalence point is reached. In this titration, the indicator turns
State whether each of the statements below is true or false. Justify your answer in each case.(a) Electrolyte solutions conduct electricity because electrons are moving through the solution.(b) If
State whether each of the statements below is true or false. Justify your answer in each case.(a) When methanol, CH3OH, is dissolved in water, a conducting solution results.(b) When acetic acid,
We have learned in this chapter that many ionic solids dissolve in water as strong electrolytes, that is, as separated ions in solution. Which statement is most correct about this process?(a) Water
Would you expect that anions would be physically closer to the oxygen or to the hydrogens of water molecules that surround it in solution?
During a normal breath, our lungs expand about 0.50 L against an external pressure of 1.0 atm. How much work is involved in this process (in J)?
Specify what ions are present in solution upon dissolving each of the following substances in water:(a) FeCl2(b) HNO3(c) (NH4)2SO4(d) Ca(OH)2.
Specify what ions are present upon dissolving each of the following substances in water:(a) MgI2(b) K2CO3(c) HClO4(d) NaCH3COO.
Which ions remain in solution, unreacted, after each of the following pairs of solutions is mixed?(a) Potassium carbonate and magnesium sulfate.(b) Lead nitrate and lithium sulfide.(c) Ammonium
You know that an unlabeled bottle contains an aqueous solution of one of the following: AgNO3, CaCl2, or Al2(SO4)3. A friend suggests that you test a portion of the solution with Ba(NO3)2 and then
Write balanced molecular and net ionic equations for the following reactions, and identify the gas formed in each:(a) Solid cadmium sulfide reacts with an aqueous solution of sulfuric acid(b) Solid
Three solutions are mixed together to form a single solution in the final solution, there are 0.2 mol Pb(CH3COO)2, 0.1 mol Na2S, and 0.1 mol CaCl2 present. What solid(s) will precipitate?

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