EXTRA HOMEWORK 1A
1. When Dalton proposed that matter was composed of atoms, why was his Atomic Theory accepted?
2. For the following two compounds between oxygen and hydrogen:
Compound A
Compound B
Mass of O
Mass of H
16 grams
16 grams
1 grams
2 grams
(a) Propose formulas for the two compounds assuming that each oxygen atom weighs the same as
each hydrogen atom
(b) Propose formulas for the two compounds assuming that each oxygen atom weighs 8 times more
than each hydrogen atom
(c) Propose formulas for the three compounds assuming that each oxygen atom weighs 16 times more
than each hydrogen atom
3. Tell what discoveries were made by each of the following scientists:
(a) J.J. Thomson
(b) Lord Rutherford
4. If a model of a hydrogen atom had a diameter of 45 cm, what would have to be the diameter of the
nucleus?
*5. Nitrogen forms two compounds with oxygen, and their elemental proportions by mass are:
Compound 1
Compound 2
Compound 3
Mass of N
Mass of O
14 grams
14 grams
14 grams
8 grams
16 grams
32 grams
Assuming the atomic mass of oxygen is 16, predict the simplest formulas of these compounds
assuming that
(a) Nitrogen has an atomic mass of 14
(b) Nitrogen has an atomic mass of 7
(c) Nitrogen has an atomic mass of 91/3
*6. Using the masses of a proton and an electron, and the sizes of the atom and the nucleus, determine the
denisity of
(a) a 1H atom
(b) a 1H nucleus
EXTRA HOMEWORK 1B
1. One of the primary visible emissions from helium occurs at 632.8 nm. For this given wavelength of
light, calculate:
(a) the wavelength in meters
(b) the frequency
(c) the energy of a single photon in joules
(d) the energy of 1 mole of photons in kilojoules
2. The energy of electromagnetic radiation needed to remove electrons from the surface of cesium atoms
is 231 kJ/mol. Calculate:
(a) the energy of a single photon of this electromagnetic radiation in joules
(b) the frequency of this electromagnetic radiation
(c) the wavelength of this electromagnetic radiation, in meters
(d) the wavelength of this electromagnetic radiation, in nanometers
(e) identify this electromagnetic radiation as either visible light, infrared radiation, or unltraviolet
radiation
*3. Give the experimental evidence that supports the fact that light behaves as a wave phenomenom when
traveling throught space.
*4. The work function of an element is the energy required to remove an electron from the surface of the
solid element. The work function for lithium is 279.7 kJ/mol (that is, it takes 279.7 kJ of energy to
remove one mole of electrons from one mole of lithium atoms on the surface of lithium metal). What
is the maximum wave of light that can remove an electron from an atom on the surface of lithium
metal?
EXTRA HOMEWORK ON MEASUREMENTS
1. Indicate the difference between the measurement 25 g and the measurement 25.00 g.
2. Give the number of significant figures in each of the following measurements:
(a) 7.5
(b) 7.50
(c) 19.0
(e) 40.10
(f) 8.30
(g) 31,000
(j) 0.090
(k) 7.31  10
(i) 0.2025
(d) 10.08
(h) 31,000.
-4
(l) 7.30  10-4
3. Perform each of the following mathematical operations, and express the answer to the correct number
of significant figures:
(a) 9.15 / 4.970
(b) (2.290  106) / (6.7  104)
(c) 0.004 + 0.09879
(d) 19.6 + 58.33 – 4.974
(e) (24.6681 x 2.38) + 332.58
(f) (9443 + 45 – 9.9)(8.1 x 106)
(continued on next page)
4. Do the following metric conversions:
(a) 0.298 kilograms to grams
(b) 16.0 centiliters to liters
(c) 3.75 kilojoules to millijoules
(d) 525 micrometers to decimeters
5. Give the readings for the following graduated glassware:
*6. Convert 40.0 km/hr to m/s.
*7. Convert 25.0 miles/hr to furlongs/fortnight
*8. The distance from the sun to the Earth is 92,960,000 miles. Calculate:
(a) this distance in kilometers
(b) the amount of time it takes light to travel from the sun to the Earth
EXTRA HOMEWORK 1C
1. If a hydrogen emission tube produced white light instead of lavendar light:
(a) what wavelenths of light are being emitted in hydrogen’s emission spectrum?
(b) what would this mean about the position of an electron in a hydrogen atom?
2. Draw an electronic energy diagram for a hydrogen atom, and using vertical lines show the following 3
transitions:
(a) n = 5  n = 2
(b) n = 4  n = 1
(c) n = 2  n = 4
3. Calculate the de Broglie wavelength of an electron moving at 99% the speed of light.
4. What are the results of passing a beam of electrons through two slits?
*5. From the Heisenberg uncertainty principle, calculate the uncertainty in position (x) of a baseball
(mass = 0.145 kg) with v = 0.100 m/s. (Planck’s constant, h, is 6.626  10-34 kgm2/s)
EXTRA HOMEWORK 1D
1. Tell whether each of the following orbital designations are allowed of forbidden based upon the
Schrödinger Equation.
(a) 1p
(b) 3f
(c) 7d
(d) 6h
(c) 3p
(d) 3d
2. Draw a picture of each of the following orbitals.
(a) 2s
(b) 2p
3. Concerning the fourth energy level of a hydrogen atom, tell:
(a) tell the names of each sublevel it has
(b) sketch the radial probability distribution for the orbitals of each sublevel
4. Give the maximum number of electrons in an atom that can have the following designations.
(a) n = 4
(b) n = 10
(e) 5py
(f) 4dx2-y2
(c) 6d
(d) 12s
5. Give the orbital notation for the following atoms:
(a) C
(b) O
(c) P
*6. Although no currently known elements contain electrons in g orbitals in the ground state, electrons in
excited states can be in g orbitals.
(a) give the lowest value for n for which a g sublevel exists
(b) give the number of electrons that a g sublevel could hold
*7. Concerning the sixth energy level of a hydrogen atom, tell:
(a) tell the names of each sublevel it has
(b) tell the number of orbitals the sixth energy level has
EXTRA HOMEWORK ON THE BOHR ATOM
1. An electron drops from the fourth Bohr Orbit to the third Bohr Orbit in a hydrogen atom. Determine:
(a) the energy released
(b) the wavelength of electromagnetic radiation emitted
(c) identify this electromagnetic radiation as either visible light, infrared radiation, or unltraviolet
radiation
2. An excited hydrogen atom has its electron in the n = 5 energy level. For this atom, determine:
(a) the energy needed to ionize it
(b) whether or not visible light with a wavelength of 525 nm will ionize it
*3. An electron starting in the 6th Bohr orbit releases a photon with a wavelength of 2627 nm. What Bohr
orbit did the electron drop to?
*4. Calculate the energy of the ground state electron in (a) a He+ ion and (b) a Li2+ ion.
EXTRA HOMEWORK 1E
1. Give the electron configuration notations and the electron dot notations for the following atoms:
(a) Na
(b) Cr
(c) Po
(d) Pu
2. For the following electron configuration notations of sodium, identify each as a ground state electron
configuration, an excited state electron configuration, or an impossible electron configuration:
(a) 1s22s22p53s2
(b) 1s22s22p63d1
(c) 1s22s22p63s1
(d) 1s22s22p62d1
3. Using the periodic table, give the number of protons, neutrons and electrons in each of the following
atoms:
(a) 40Ca
(b) 51V
(c) 79Br(d) 252Cf
4. What is probably the most abundant isotope of thorium?
*5. Why does the 2s orbital fill before the 2p orbitals in multielectron atoms?
*6. Why does the 4s orbital fill before the 3d orbitals in multielectron atoms?
*7. In the ground state of mercury,
(a) How many electrons occupy atomic orbitals with n = 3?
(b) How many electrons occupy d atomic orbitals?
(c) How many electrons occupy pz atomic orbitals?
(d) How many electrons have spin “up”?
*8. Which of elements 1-36
(a) have one unpaired electron in its ground state?
(b) have two unpaired ectrons in its ground state?
*9. Give the electron configuration notations for the following atoms:
(a) Mo
(b) Ag
EXTRA HOMEWORK 1F
1. Indicate the isotope in each pair that is most likely to be radioactive.
(a)
15
O or 16O
(b)
19
F or
20
F
(c)
100
Sn or
120
Sn
2. Radioactive 110Ag with a half-life of 24 seconds is used by forensic scientists to identify trace amounts
of the element in bullet lead. How many seconds will it take for the radioactivity of a 110Ag sample to
fall to 3.125% of its original intensity?
3. The age of a rock was to be determined by 238U dating. 238U has a half-life of 4.5 x 109 years, and
eventually decays into stable 206Pb. If a sample of rock shows that 50% of its 238U had been converted
into 206Pb, how old is the rock?
4. What is the most massive element produced by fusion in stars?
*5. The equation that governs radioactive decay is:
n
= noe-
(ln 2 / t1/2)t
where
n
no
t1/2
t
=
=
=
=
the final number of radioactive atoms remaining after the decay time, t
the initial number of radioactive atoms
the half-life of the radioactive atoms
the length of time the radioactive atoms have been decaying
Radioactive tritium, 3H, has a half-life of 12.3 years and is used as a tracer in organic chemistry
reactions. How many years will it take for the radioactivity to fall to 10.0% of its original intensity?
EXTRA HOMEWORK 1G
1. Magnesium has the following stable isotopes:
24
Mg
Mg
26
Mg
23.985045 u
24.985840 u
25.982591 u
25
78.70%
10.13%
11.17%
What is the value of the elemental atomic mass for magnesium calculated from these data?
2. The element indium exists in nature as two isotopes:
113
115
In
In
112.9 amu
114.9 amu
Using the periodic table in your textbook, calculate the natural percentages of the two indium isotopes.
3. Give the mass, in grams, necessary to have one mole of atoms of each of the following elements:
(a) beryllium
(b) sulfur
(c) nickel
(d) tin
4. A sample of lead has a mass of 25.0 g. Calculate:
(a) the number of moles of lead atoms.
(b) the number of atoms of lead.
5. A sample of antimony contains 2.75  1022 antimony atoms. Calculate:
(a) the number of moles of antimony atoms.
(b) the number of grams of antimony.
*6. A 13C atom has a mass of 13.00335 u. What is its mass in grams?
*7. A regular garden pea has a volume of about 0.5 milliliters. In contrast, the Empire State building has a
volume of approximately 1 billion liters. Calculate the number of Empire State Buildings it would
take to hold 1 mole of regular garden peas.
EXTRA HOMEWORK 1H
1. What was Mendeleev’s Periodic Law, and how is it different from the modern Periodic Law.
2. What is similar about elements in the same period on the periodic table?
3. For element 120, Ubn:
(a) predict its expected electron configuration notation
(b) predict what other element it will most likely resemble chemically
4. Explain the following trends in atomic radii:
(a) atomic radii increase moving down a group on the periodic table
(b) atomic radii decrease moving across a period on the periodic table
5. Identify the atom in each pair with the largest atomic radius, and explain why:
(a) K, Cs
(b) Sn, I
*6. For element 121, Ubu, predict its expected electron configuration notation.
EXTRA HOMEWORK 1I
1. Write the equations for the first, second and third ionizations of an oxygen atom.
2. Explain why
(a) ionization energies decrease (become less endothermic) moving down a group on the periodic
table
(b) ionization energies increase (become more endothermic) moving across a period on the periodic
table
3. Explain the two exceptions to the trend of ionization energies increasing (becoming more
endothermic) moving across a period on the periodic table
4. Identify the atom with the greatest (most endothermic) first ionization energy, and explain why:
(a)
Cu, Ag
(b) Ti, V
(c) Sr, In
(d) Bi, Po
5. Elements X and Y are known to be second or third period elements on the periodic table. The first
four ionization energies for elements X and Y are shown below. The units are not kJ/mol.
First
Second
Third
Fourth
X
Y
170
350
2200
2800
200
400
3500
4300
Identify elements X and Y.
6. Write the equations for the first, second, and third electron affinities of an oxygen atom.
7. Explain why
(a) electron affinities decrease (become less exothermic) moving down a group on the periodic table
(b) Explain why the electron affinities increase (become more exothermic) moving across a period on
the periodic table
8. Explain the two types of exceptions to the trend of ionization energies increasing (becoming more
exothermic) moving across a period on the periodic table.
9. Identify the atom with the greatest (most exothermic) first electron affinity, and explain why:
(a) Ni, Pd
(b) Ti, V
(c) Cs, Ba
(d) Pb, Bi
EXTRA HOMEWORK 1J
1. Give examples of the physical properties of metals and nonmetals.
2. Why do metals form positive ions and nonmetals form negative ions?
3. Give the most metallic element in each pair:
(a) K, Ca
(b) Sn, Pb
4. Give the charge of the expected ion ion for each of the following elements:
(a) I
(b) Rb
(c) Se
(d) Sr
(e) As
(f) In
(g) Cd
(h) Fe
5. Give the charges of the two ions expected for each of the following elements:
(a) Tl
(b) Pb
(c) Bi
6. Why do the atoms of Group 1 elements form 1+ ions?
7. Why do the atoms of Group 2 elements form 2+ ions?
8. Why do atoms of the d-sublevel elements form a variety of positive ions?
9. Why do the atoms of Group 17 elements form 1- ions?
10. Why don’t the atoms of Group 18 elements form ions?
EXTRA 1A ANSWERS
1. Dalton’s Atomic Theory explained the Law of Definite Proportion.
2. (a) HO16, HO8
(b) HO2, HO
3. (a) discovered the electron
(c) HO, H2O
(b) discovered the nucleus of the atom
4. 0.00045 cm or 4.5 μm
*5. (a) N2O, NO, NO2
*6. (a) 3 g/cm3
(b) N4O, N2O, NO
(c) N3O, N3O2, N3O4
(b) 3 x 1015 g/cm3
EXTRA 1B ANSWERS
1. (a) 6.328 x 10-7 m
(b) 4.738 x 1014 s-1
(c) 3.139 x 10-19 J
(d) 1.890 x 102 kJ
2. (a) 3.84 x 10-19 J
(b) 5.79 x 1014 s-1
(c) 5.18 x 10-7 m
(d) 518 nm
(e) visible light
*3. light passing through 2 slits produces a diffraction pattern
*4. 427.7 nm
EXTRA MEASUREMENTS ANSWERS
1. 25 g indicates that the measurement is between 24 g and 26 g, while 25.00 g indicates that the
measurement is between 24.99 g and 25.01 g
2. (a) 2
(b) 3
(c) 3
(d) 4
(e) 4
(f) 3
(g) 2
(h) 5
(i) 4
(j) 2
(k) 3
(l) 3
3. (a) 1.84
(b) 34
(c) 0.103
(d) 73.0
(e) 391.3
(f) 7.7 x 1010
4. (a) 298 g
(b) 0.160 L
(c) 3,750,000 mJ
5. (a) 8.70 mL
(d) 0.00525 dm
(b) 10.35 mL
(c) 23.5 mL
*6. 11.1 m/s.
*7. 67,200 furlongs/fortnight
*8. (a) 1.496 x 108 km
(b) 498.9 s or 8.314 min
(d) 17.80 mL
EXTRA 1C ANSWERS
1. (a) all wavelenths of visible light are being emitted
(b) an electron could be found at any distance from the nucleus, not just at a finite number of
quantized distances
2.
(a)
(b)
(c)
3. 2.451 x 10-12 m
4. a diffraction pattern is produced
*5. 3.64 x 10-33 m
EXTRA 1D ANSWERS
1. (a) forbidden
(b) forbidden
(c) allowed
(d) allowed
2. (a)
(b)
(c)
(d)
(continued on next page)
3. (a) 4s, 4p, 4d, 4f
4. (a) 32
(e) 2
(b)
(b) 200
(c) 10
(b) 2
5.
(a)
(b)
(c)
*6. (a) n = 5
(b) 18
*7. (a) 6s, 6p, 6d, 6f, 6g, 6h
(b) 36
(d) 2
EXTRA BOHR ATOM ANSWERS
1. (a) 1.059 x 10-19 J
(b) 1.876 x 10-6 m
2. (a) 8.712 x 10-20 J
(b) yes, 3.78 x 10-19 J > 8.712 x 10-20 J
(c) infrared radiation
*3. fourth
*4. (a) -5.445 x 10-19 J
(b) -2.420 x 10-19 J
EXTRA 1E ANSWERS
1. (a) [Ne]3s1
(c) [Xe]6s24f145d106p4
Na.
̤
. Po :
.
(b) [Ar]4s13d5
Cr.
(d) [Rn]7s25f6
Pu :
2. (a) excited
(b) excited
(c) ground
(d) impossible
3. (a) 20 p, 20 n, 20 e
(b) 23 p, 28 n, 23 e
(c) 35 p, 44 n, 36 e
(d) 98 p, 154 n, 98 e
4.
232
Th
*5. Electrons in a 2s orbital have more probability inside the shielding of the first energy level electrons
than electrons in a 2p orbital, resulting in greater attraction, and therefore a lower energy state.
*6. Electrons in a 4s orbital have more probability inside the shielding of the finner energy level electrons
than electrons in a 3d orbital, resulting in greater attraction, and therefore a lower energy state.
*7. (a) 18
(b) 30
(c) 8
(d) 40
*8. (a) H, Li, B, F, Na, Al, Cl, K, Sc, Cu, Ga, Br
(b) C, O, Si, S, Ti, Ni, Ge, Se
*9. (a) [Kr]5s14d5
(b) [Kr]5s14d10
EXTRA 1F ANSWERS
1. (a)
15
O
(b)
20
F
(c)
100
Sn
2. 120 seconds
3. 4.5 x 109 years
4. Iron
*5. 40.9 years
EXTRA 1G ANSWERS
1. 24.31 u
2. 5% 113In, 95% 115In
3. (a) 9.012 g
(b) 32.07 g
(c) 58.69 g
4. (a) 0.121 mol
(b) 7.27 x 1022 atoms
5. (a) 0.0457 mol
(b) 5.56 g
*6. 2.16 x 10-23 g
*7. 300 billion
(d) 118.7 g
EXTRA 1H ANSWERS
1. Mendeleev - the properties of the chemical vary with their atomic masses in a systematic way.
Modern - the properties of the chemical vary with their atomic numbers in a systematic way.
2. Atoms of the elements in the same period require the same number of energy levels to hold all of their
electrons (they all have the same number of energy levels).
3. (a) [Uno]8s2
(b) Ra
4. (a) Atomic radii increases moving down a group because even though the nuclear charge is
increasing, the number of shielding energy levels is increasing, so the outer shell electorns are not
attracted as close to the nucleus
(b) Atomic radii decreases moving across a period because the nuclear charge is increasing while the
shielding of the nuclear charge remains the same, so the outer shell electrons are attracted closer
to the nucleus
5. (a) Cs – even though it has a greater nuclear charge it has more shielding energy levels, so the outer
shell electrons are not attracted as close to the nucleus
(b) Sn – has a lower nuclear charge with the same number of shielding energy levels, so the outer
shell electrons are not attracted as close to the nucleus
*6. [Uno]8s25g1
EXTRA 1I ANSWERS
1. O(g)  O+(g) + eO+ (g)  O2+(g) + eO2+ (g)  O3+(g) + e2. (a) 1st IE decreases (becomes less endothermic) moving down a group because the removed e- is
more shielded from the nuclear charge, even though the nuclear charge is increasing, so the e- is
attracted less to the nucleus, and therefore requires less energy to remove
(b) The 1st IE increases (becomes more endothermic) moving across a period because the removed eis attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the
same, so the e- is attracted more to the nucleus, and therefore requires more energy to remove
3. Group 13 - The ionized e- of a Group 2 atom is in an s orbital, but the ionized e- of a Group 13 atom is
in a p orbital, which is more shielded from the nuclear charge, so it is attracted less to the nucleus, and
therefore requires less energy to remove
Group 16 - The ionized e- of a Group 15 atom is an unpaired e-, but the ionized e- of a Group 16 atom
is a paired e-, which experiences repulsion from the other electron, and therefore requires less energy
to remove
(continued on next page)
4. (a) Cu – 1st e- removed from Cu is less shielded from the nuclear charge, even though the nuclear
charge is less, so the e- is attracted more to the nucleus, and therefore requires more energy to
remove
(b) V – 1st e- removed from V is attracted by a greater nuclear charge, while the shielding of the
nuclear charge remains the same, so the e- is attracted more to the nucleus, and therefore requires
more energy to remove
(c) Sr – 1st e- removed from Sr is in an s orbital, but the 1st e- removed from In is in a p orbital; the eremoved from In is more shielded from the nuclear charge, so it is attracted less to the nucleus,
and therefore requires less energy to remove
(d) Bi – 1st e- removed from Bi is an unpaired e-, but the 1st e- removed from Po is a paired e; the
removed e- from Po experiences repulsion from the other electron, and therefore requires less
energy to remove
5. X = Mg, Y = Be
6. O(g) + e-  O-(g)
O-(g) + e-  O2-(g)
O2-(g) + e-  O3-(g)
7. (a) 1st EA decreases (becomes less exothermic) moving down a group because the added e- is more
shielded from the nuclear charge, even though the nuclear charge is increasing, so the e- is
attracted less to the nucleus, and therefore releases less energy when it is added
(b) The 1st EA increases (becomes more exothermic) moving across a period because the added e- is
attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the
same, so the e- is attracted more to the nucleus, and therefore releases more energy when it is
added
8. Group 2 - The added e- to a Group 1 atom goes into an s orbital, but the added e- to a Group 2 atom
goes into a p orbital, which is more shielded from the nuclear charge, so it is attracted less to the
nucleus, and therefore releases less energy when it is added
Group 15 - The added e- to a Group 14 atom is will be an unpaired e-, but the added e- to a Group 15
atom will be a paired e-, which experiences repulsion from the other e-, and therefore releases less
energy when added
Group 18 - The added e- to a Group 17 atom goes into a p orbital, but the added e- to a Group 18 atom
goes into an s orbital of a higher energy level, which is more shielded from the nuclear charge, so it is
attracted less to the nucleus, and therefore releases less energy when it is added
9. (a) Ni – the added e- to Ni is less shielded from the nuclear charge, even though the nuclear charge is
less, so the e- is attracted more to the nucleus, and therefore releases more energy when it is added
(b) V – the added e- to V is attracted by an increasing nuclear charge, while the shielding of the
nuclear charge remains the same, so the e- is attracted more to the nucleus, and therefore releases
more energy when it is added
(c) Cs – the added electron to a Cs atom goes into an s orbital, but the added electron to a Ba atom
goes into a p orbital; the e- added to Ba is more shielded from the nuclear charge, so it is attracted
less to the nucleus, and therefore releases less energy when it is added
(d) Pb – the added e- to a Pb atom will be an unpaired e-, but the added e- to a Bi atom will be a paired
e-; the e- added to Bi will experience repulsion from the other e-, and therefore releases less energy
when added
EXTRA 1J ANSWERS
1. metals – lustrous, malleable, ductile, conductors of heat and electricity; nonmetals – opposite
2. metals have low ionization energies and low electron affinities, therefore they lose electrons easily
(forming positive ions) but it is difficult for them to gain electrons
nonmetals have high ionization energies and high electron affinities, therefore it is difficult for them to
lose electrons, but they gain electrons easily (forming negative ions)
3. (a) K
(b) Pb
4. (a) 1-
(b) 1+
(c) 2-
(d) 2+
(e) 3-
(f) 3+
(g) 2+
(h) forms more than 1
(b) 4+, 2+
(c) 5+, 3+
5. (a) 3+, 1+
6. Group 1 elements have one outershell electron. That electron has a low ionization energy, so it is
removed easily. Further electrons are core electrons (from inner energy levels), and they have high
ionization energies, so they are difficult to remove. With one electron being removed easily, those
atoms form 1+ ions. Group 1 elements have low electron affinities, so they do not gain electrons.
7. Group 2 elements have two outershell electrons. Those two electrons have low ionization energies, so
they are removed easily. Further electrons are core electrons (from inner energy levels), and they have
high ionization energies, so they are difficult to remove. With two electrons being removed easily,
those atoms form 2+ ions. Group 2 elements have low electron affinities, so they do not gain
electrons.
8. For the d-sublevel elements, their outershell s electrons have low ionization energies, so they are
removed easily. Their inner d electrons also have fairly low ionization energies, so they may be
removed as well, forming different ions with higher positive charges.
9. Group 17 elements have one opening for an electron in their outershell electron. The electron affinity
to fill that spot is high, so an electron is gained easily. Further electrons would have to go into higher
energy levels, and their electron affinities would be very low, so they are difficult to gain. With one
electron being gained easily, those atoms form 1- ions. Group 17 elements have high ionization
energies, so they do not lose electrons.
10. Group 18 elements have high ionization energies so they do not lose electrons, and low electron
affinities so they do not gain electrons.