Chapter 12
The nucleus of an electrically neutral iron atom contains 26 protons. How many electrons does this iron atom have?
26
If an element has 15 protons and 16 neutrons and 15 electrons, what is the atomic mass of the element?
31
What is the main difference between a conceptual model and a physical model?
A physical model represents the shape and form while a conceptual model describes how a system behaves.
Considering how small atoms are, what are the chances that at least one of the atoms exhaled in your first breath will be in your last breath?
very probable because of how incredibly small atoms are
Which of the following best explains what is happening when an atom emits light?
An electron is dropping from a higher to a lower energy level with the difference in energy between the two being emitted as light.
Which atom is smallest?
Be
Which color of light comes from the higher energy transition, red or blue?
Blue is a higher frequency and therefore corresponds to a higher energy level transition.
A cat strolls across your backyard. An hour later, a dog with its nose to the ground follows the trail of the cat. Explain what is going on from a molecular point of view.
The dog is smelling molecules from the cat.
A beam of protons and a beam of neutrons of the same energy are both harmful to living tissue. The beam of neutrons, however, is less harmful. Why?
Neutrons carry no electric charge and thus have a greater likelihood of passing through the tissue.
Since atoms are mostly empty space, why don't objects pass through one another?
The electrons on the atoms repel other electrons on other atoms when they get close.
If all the molecules of a body remained part of that body, would the body have any odor?
No, because there would be no molecules traveling to our nose.
The shell model presented in this book is not very accurate. Why then is it presented?
The shell model is simpler and easy to understand.
Some older cars vibrate loudly when driving at particular speeds. For example, at 65 mph the car may be most quiet, but at 60 mph the car rattles uncomfortably. How is this analogous to the quantized energy levels of an electron in an atom?
The vibrating car is analogous to one of the energy levels of the electron, which is the point at which the electron experiences resonance.
Should the periodic table be memorized? Why or why not?
No. The periodic table is a reference to be used, not memorized.
What property of an electron makes it possible to use electron microscopes?
They have shorter wavelengths than visible light.
Does a shell have to contain electrons in order to exist?
Two of the above are reasonable answers.
In what sense can you truthfully say that you are a part of every person around you?
We are continually exchanging our atoms.
Why can't we see atoms?
We see with light energy and the wavelength is larger than the object and so it is not reflected.
How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?
When an electron wave is confined, it is reinforced only at particular frequencies.
You could swallow a capsule of germanium, Ge (atomic number 32), without significant ill effects. If a proton were added to each germanium nucleus, however, you would not want to swallow the capsule because the germanium would
become arsenic
How can a hydrogen atom, which has only one electron, have so many spectral lines?
One electron can be boosted to many different energy levels.
Which of these properties describes a metal?
conducts heat very well
Using the following generic atom description, choose the correct method for determining the number of neutrons. F G X
Subtract G from F
When we breathe we inhale oxygen, O2, and exhale carbon dioxide, CO2, plus water vapor, H2O. Which likely has more mass, the air that we inhale or the same volume of air we exhale? Does breathing cause you to lose or gain weight?
The air we exhale has more mass; Breathing causes you to lose weight.
Why are the atomic masses listed in the periodic table not whole numbers?
The atomic masses are average atomic masses.
What happens to the properties of elements across any period of the periodic table?
The properties of the elements gradually change across any period of the periodic table.
The ________ represents the complete range of frequencies of light energy from radio waves to cosmic rays.
electromagnetic spectrum
Which of the following statements describes an isotope?
element with the same number of protons but a different number of neutrons
What are metalloids?
elements that have some properties like metals and some like nonmetals
An electron de-excites from the fourth quantum level to the third and then directly to the first. Two frequencies of light are emitted. How do their combined energies compare to the energy of the single frequency that would be emitted by de-excitation from the fourth level directly to the first level? Answer: The combined energies of the two frequencies emitted by the one electrons is
equal to the energy of the single frequency.
If an element has 10 protons and 11 neutrons and 10 electrons, which expression correctly identifies the element?
neon-21
The repeating trends that take place when examining the elements are called ________.
periodicity
Would you use a physical model or a conceptual model to describe the following: the brain; the mind; the solar system; the beginning of the universe?
physical; conceptual; physical; conceptual
Which of the following describes a nonmetal?
poor conductor of electricity
Which of the following elements will most likely be shiny and flexible?
rhodium (Rh)
Which of these is not a metal?
selenium (atomic no. = 34)
Suppose that a certain atom possesses only four distinct energy levels. Assuming that all transitions between levels are possible, how many spectral lines will this atom exhibit?
six
About how many elements do you have access to as a consumer of market goods.
ten
Which chemical family is composed almost entirely of man-made elements?
the actinides
Which of the following could NOT be represented by a conceptual model?
the floor plan of a house
The following statement describes which subatomic particle best? It is electrically charged.
A and B (An electron and a proton)
How might the spectrum of an atom appear if its electrons were not restricted to particular energy levels?
A broad spectrum of all colors would be observed.
What is the approximate mass of a carbon atom in atomic mass units (amu)? How about a carbon dioxide molecule?
A carbon atom has a mass of about 12 amu. Carbon dioxide would then have a mass of 44 amu.
What is the valence shell?
It is the outermost shell of electrons in an atom.
Which of the following statements does not describe a proton?
It orbits around the nucleus of an atom.
Which element has the atomic number 12?
Mg
If a neutral element has 8 neutrons and 7 electrons, which expression correctly identifies the element?
15 7 N
Boron has primarily two isotopes, one with an atomic mass of 11 amu and another with an atomic mass of 10 amu. If the abundance of the boron atom with a mass of 11 amu is 18.9 percent and the abundance of the other isotope is 81.1 percent, what would be the average mass of the boron atom?
10.19 amu
If a neutral element has the following chemical notation, how many electrons does it have? carbon-13
6
If a neutral element has the following chemical symbol, how many electrons does it have? 18 6 O
6
The isotope lithium-7 has a mass of 7.0160 atomic mass units, and the isotope lithium-6 has a mass of 6.0151 atomic mass units. Given the information that 92.58 percent of all lithium atoms found in nature are lithium-7 and 7.42 percent are lithium-6, calculate the atomic mass of lithium, Li (atomic number 3).
6.942 amu
An element found in another galaxy exists as two isotopes. If 80.0 percent of the atoms have an atomic mass of 80.00 atomic mass units and the other 20.0 percent have an atomic mass of 82.00 atomic mass units, what is the atomic mass of the element?
80.4 atomic mass units
If a neutral element has the following chemical notation, how many electrons does it have? fluorine-19
9
If a neutral element has the following chemical symbol, how many electrons does it have? 235 92 U
92
An atom absorbs or emits only particular frequencies of light. White light bends into a glass prism and separates into a rainbow of colors. In which of these two scenarios does the electromagnetic radiation behave as a wave? As a particle?
Absorption of light shows particle behavior while bending of light shows wave behavior.
What do the components of a conceptual model have in common?
All components interact with each other.
Which of the following statements is false?
An atom emits electromagnetic radiation when an electron moves from a lower energy level to a higher energy level.
The following statement describes which subatomic particle best? It has a relatively large mass.
B and C (a proton and a neutron)
The following statement describes which subatomic particle best? It is a nucleon.
B and C (a proton and a neutron)
Which element would have chemical properties the most similar to chlorine (Cl)?
Br
The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50 percent. The atomic mass of bromine is reported in the periodic table as 79.904 atomic mass units. Choose the most likely set of mass numbers for these two bromine isotopes.
Br-79 Br-81
Which of the following elements are in the same group as silicon (Si)?
C
Which of the following elements are in the same period as magnesium (Mg)?
Cl
In some instances electromagnetic radiation behaves like a wave. In other instances electromagnetic radiation behaves more like a particle. Which behavior more accurately describes the true nature of electromagnetic radiation?
Electromagnetic radiation behaves both as a wave or as a particle depending on the circumstance.
What was Niels Bohr's explanation for the observation of atomic spectra?
Electrons could only move in discrete energy steps within an atom.
What is the main tenet of Plank's quantum hypothesis?
Energy comes in discrete packets of a certain minimum size.
Which element has the atomic number 9?
F
How is it possible to deduce the identity of an element from its electron configuration?
If the atom is electrically neutral, the number of electrons corresponds to the atom's atomic number.
Where did the atoms that make up a newborn baby originate?
In the explosions of ancient .
If you remove two protons and two neutrons from a gold atom (Au), what new element is formed (if any)?
Ir
Which of the following does not describe a neutron?
It has a positive charge equivalent but opposite of an electron's.
Which contributes more to an atom's mass: electrons or protons? Which contributes more to an atom's size?
Protons contribute more to an atom's mass while electrons contribute more to its size.
Which atom is the largest?
Rb
If you remove two protons and two electrons from a sulfur atom (S), what new element is formed?
Si
Which of the following elements is a transition metal?
Silver (Ag)
An element has two different isotopes: one that weighs 65 amu and another that weighs 67 amu. If the average atomic mass of all the isotopes is 66.5 amu, what can be said about the relative abundance of the isotopes?
The isotope with the mass of 67 is more abundant than the isotope with the mass of 65.
Evidence for the existence of neutrons did not come until many years after the discoveries of the electron and the proton. Give a possible explanation.
The neutron lacks an electrical charge.
Why isn't dirt listed in the periodic table?
The periodic table lists only elements made of one kind of material. Dirt is a mixture of elements and compounds.
How do we account for the great variety of substances in the world?
There are many possible combinations of atoms.
Which are older, the atoms in the body of an elderly person or those in the body of a baby?
They are of the same age, which is appreciably older than the solar system.
Which of the following might best explain the reason why electrons are restricted to certain energy levels in an atom?
They behave like restricted waves and are self-reinforcing.
Consider the various frequencies of the three photons emitted from the following three individual electron transitions in the figure below: n=3 to n=2; n=2 to n=1; n=3 to n=1. These transitions would produce three spectral lines in a spectroscope. If the energy spacing between the levels were equal, would this affect the number of spectral lines?
Yes, two otherwise separate lines would converge into a single more intense line.
Does it make sense to say that a textbook is about 99.9 percent empty space?
Yes. A textbook like all material things is made up of atoms, which are considered to be 99.9 percent empty space.
How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope?
You would see a series of very sharp lines of emitted light
Which has more atoms: a 1-gram sample of carbon-12 or a 1-gram sample of carbon-13?
a 1-gram sample of carbon-12
Which of the following could be represented by a physical model?
a cell
What does the following element description actually mean? 238 92 U
a uranium atom with 92 protons and 146 neutrons
Which of the following physical properties would you expect for krypton (Kr)?
a gas room temperature
What does the following element description actually mean? hydrogen- 2
a hydrogen with one neutron and one proton
Which of the following statements best describes an element?
a material consisting of only one type of atom
Which of the following best describes a conceptual model of an atom?
a model that illustrates the tendency of an atom to undergo radioactive decay and the products it produces
The following statement describes which subatomic particle best? It does not have an electrical charge.
a neutron
Which of the following is a property of light?
all of the above
Which of the following statements about electrons is true?
all of the above
Which of the following images could describe an element at the atomic level?
all of the images
The following statement describes which subatomic particle best? It is located outside of the nucleus.
an electron
What does the following element description actually mean? 18 6 O
an oxygen atom with 6 protons and 12 neutrons
Which of the following is a metalloid?
antimony (atomic no. =51)
Which of the following elements is a gas at room temperature?
argon (Ar)
If an element has 18 protons and 20 neutrons and 18 electrons, which expression correctly identifies the element?
argon-38
If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?
atomic mass, 99 amu; Technetium
If two protons and two neutrons are removed from the nucleus of an oxygen atom, a nucleus of which element remains?
carob-12
Which of the following elements is a halogen?
chlorine (Cl)
Which of the following elements is in the fourth period?
chromium (Cr)
If an atom were the size of a baseball, its nucleus would be about the size of a(n)
flea
Which of these does not describe a metal at room temperature?
gas
Elements that are in the same ________ have a tendency to have very similar chemical properties due to periodic trends.
group
Which of the following is not the name of a chemical family?
heavy metals
Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because
helium is the most similar to other group 18 elements
Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20). This fact relates to the organization of the periodic table in that strontium and calcium are both
in group 2 of the periodic table.
What does the following element description actually mean? iron-57
iron with a mass number of 57
Which of the following elements is an alkali metal?
lithium (Li)
How might you distinguish a sodium-vapor street lamp from a mercury-vapor street lamp?
look at the street lamps through a spectroscope and match their spectral patterns to their respective atomic spectra
Light is emitted as an electron transitions from a higher energy state to a lower energy state. How long does it take for the actual transition to take place?
no time at all
How many electrons are there in the third shell of sodium, Na (atomic number 11)?
one
Which of the following is said to be quantized?
the number of eggs in an egg carton
Which of the following diagrams best represents the size of the atomic nucleus relative to the size of the atom?
the picture with nothing in the middle
The mass number of an element is ________.
the sum of the protons and neutrons
What do the electron configurations for all the group 18 noble gases have in common?
their outermost occupied shells are filled to capacity
Oxygen, O, (number 8), sulfur, S, (number 16), and selenium, Se, (number 34) have such similar chemical properties because
their outermost shells contain the same number of electrons.
Which of the following is not a nonmetal?
titanium (atomic no. 22)