?Would you use a physical model or a conceptual model to describe the following: a gold

Which is the oldest element?

Is it possible to see an atom using visible light?

What is at the center of every atom?

How many types of atoms can you expect to find in a pure sample of any element?

Distinguish between an atom and an element.

What is the atomic symbol for the element cobalt?

What role does atomic number play in the periodic table?

Distinguish between atomic number and mass number.

Distinguish between mass number and atomic mass.

Are most elements metallic or nonmetallic?

How many periods are there in the periodic table? How many groups?

What happens to the properties of elements across any period of the periodic table?

If a baseball were the size of Earth, about how large would its atoms be?

When we use a scanning probe microscope, do we see atoms directly or do we see them only indirectly?

What is the difference between a physical model and a conceptual model?

What does a spectroscope do to the light coming from an atom?

What causes an atom to emit light?

Why do we say atomic spectra are like fingerprints of the elements?

What was Planck’s quantum hypothesis?

Which has more potential energy: an electron close to an atomic nucleus or one far from an atomic nucleus?

Did Bohr think of his planetary model as an accurate representation of what an atom looks like?

Who first proposed that electrons exhibit the properties of a wave?

About how fast does an electron travel around the atomic nucleus?

How does the speed of an electron change its fundamental nature?

Does the periodic table explain the shell model, or does the shell model explain the periodic table?

Which electrons are most responsible for the properties of an atom?

What is the relationship between the maximum number of electrons each shell can hold and the number of elements in each period of the periodic table?

Fluorescent lights contain spectral lines from the light emission of mercury atoms. Special coatings on the inner surface of the bulb help to accentuate visible frequencies, which can be seen through the diffraction grating reflection of a compact disc (CD). Cut a narrow slit through some thick paper (or thin cardboard), and place it over a bright fluorescent bulb. View this slit at an oblique angle against a CD and look for spectral lines. Place the slit over an incandescent bulb, and you’ll see a smooth, continuous spectrum (no lines), because the incandescent filament glows at all visible frequencies. Try looking at different brands of fluorescent bulbs. You’ll also be able to see spectral lines in street lights and fireworks. For those it is best to use “rainbow” glasses, which are available from a nature, toy, or hobby store.

You can “quantize” your whistle by whistling down a long tube, such as the tube from a roll of wrapping paper. First, without the tube, whistle from a high pitch to a low pitch. Do it loudly and in a single breath. (If you can’t whistle, find some one who can.) Next, try the same thing while holding the tube to your lips. Ah ha! Note that some frequencies simply cannot be whistled, no matter how hard you try. These frequencies are forbidden because their wavelengths are not a multiple of the length of the tube. Try experimenting with tubes of different lengths. To hear yourself more clearly, use a flexible plastic tube, and twist the outer end toward your ear. When your whistle is confined to the tube, the consequence is a quantization of its frequencies. When an electron wave is confined to an atom, the consequence is a quantization of the electron’s energy.

Stretch a rubber band between your two thumbs, and pluck it with your index finger. Better yet, stretch the rubber band in front of a windy fan to get it vibrating. Note that the area of greatest oscillation is always at the midpoint. This is a self-reinforcing wave that occurs as overlapping waves bounce back and forth from thumb to thumb.

A class of 20 students takes an exam, and every student scores 80%. What is the class average? Would the class average be slightly less, the same, or slightly more if one of the students instead scored 100%? How is this similar to the way we derived the atomic masses of elements?

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% of all lithium atoms found in nature are lithium-7 and 7.42% are lithium-6, show that the atomic mass of lithium, Li (atomic number 3), is 6.941 amu.

The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50%. 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: (a) Br-79, Br-81 (b) Br-79 Br-80 (c) Br-80 Br-81

Rank the following three subatomic particles in order of increasing mass: (a) the neutron, (b) the proton, and (c) the electron.

Consider these atoms: helium, He; chlorine, Cl; and argon, Ar. Rank them in terms of their atomic number, from smallest to largest.

Consider three 1-gram samples of matter: A, carbon-12; B, carbon-13; and C, uranium-238. Rank them in terms of how many atoms they have, from most to least.

Consider these atoms: helium, He; aluminum, Al; and argon, Ar. Rank them, from smallest to largest, in terms of (a) size, (b) number of protons in the nucleus, and (c) number of electrons.

Of the following three atoms, one tends to lose three electrons, another tends to lose two electrons, and another tends to lose one electron. Rank these atoms in order of the number of electrons they tend to lose, from fewest to most: sodium, Na; magnesium, Mg; and aluminum, Al.

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.

If all the molecules of a body remained part of that body, would the body have any odor?

Where did the atoms that make up a newborn baby originate?

The atoms that compose your body are mostly empty space, and structures such as the chair you’re sitting on are composed of atoms that are also mostly empty space. So why don’t you fall through the chair?

Where did the carbon atoms in Leslie’s hair originate? (Shown below is a photo of coauthor Leslie at 16.)

In what sense can you truthfully say that you are a part of every person around you?

Is the head of a politician really 99.99999999% empty space?

The air we breathe is not considered by chemists to be an element. Why not?

Are elements made of atoms or are atoms made of elements?

Name ten elements you have access to macroscopic samples of as a consumer here on Earth.

If two protons and two neutrons are removed from the nucleus of an oxygen-16 atom, a nucleus of which element remains?

If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?

The nucleus of an electrically neutral iron atom contains 26 protons. How many electrons does this iron atom have?

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.

Which has more atoms: a 1-gram sample of carbon-12 or a 1-gram sample of carbon-13? Explain.

Why are the atomic masses listed in the periodic table not whole numbers?

Which contributes more to an atom’s mass: electrons or protons? Which contributes more to an atom’s size?

What is the approximate mass of an oxygen atom in atomic mass units? What is the approximate mass of two oxygen atoms? How about an oxygen molecule?

What is the approximate mass of a carbon atom in atomic mass units? How about a carbon dioxide molecule?

Which is heavier: a water molecule, \(\mathrm{H}_{2} \mathrm{O}\), or a carbon dioxide molecule, \(\mathrm{CO}_{2}\)? Text Transcription: H_2O CO_2

When we breathe we inhale oxygen, \(\mathrm{O}_{2}\), and exhale carbon dioxide, \(\mathrm{CO}_{2}\), plus water vapor, \(\mathrm{H}_{2} \mathrm{O}\). Which probably has more mass: the air that we inhale or the same volume of air that we exhale? Does breathing cause you to lose or gain weight? Text Transcription: H_2O CO_2 O_2

As a tree respires, it takes in carbon dioxide, \(\mathrm{CO}_{2}\), and water vapor, \(\mathrm{H}_{2} \mathrm{O}\), from the air, while also releasing oxygen, \(\mathrm{O}_{2}\). Does the tree lose or gain weight as it respires? Explain. Text Transcription: H_2O CO_2 O_2

Which of the following diagrams best represents the size of the atomic nucleus relative to the size of the atom?

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. Suggest why.

Germanium, Ge (atomic number 32), computer chips operate faster than silicon, Si (atomic number 14), computer chips. So how might a gallium, Ga (atomic number 31), chip compare with a germanium chip?

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. Why?

Strontium, Sr (atomic number 38), is especially dangerous to humans because it tends to accumulate in calcium dependent bone marrow tissues (calcium, Ca, atomic number 20). How is this fact related to what you know about the organization of the periodic table?

With the periodic table as your guide, describe the element selenium, Se (atomic number 34), using as many of this chapter’s key terms as you can.

As depicted in Figure 12.19, are gallium atoms really red and arsenic atoms green?

With scanning probe microscopy technology, we see not actual atoms, but rather images of them. Explain.

Why is it not possible for a scanning probe microscope to make images of the inside of an atom?

What do the components of a conceptual model have in common?

Would you use a physical model or a conceptual model to describe the following: a gold coin, a dollar bill, a car engine, air pollution, a virus, the spread of sexually transmitted disease?

What is the function of an atomic model?

What is the relationship between the light emitted by an atom and the energies of the electrons in the atom?

How might you distinguish a sodium-vapor streetlight from a mercury-vapor streetlight?

What particle within an atom vibrates to generate electromagnetic radiation? This particle is vibrating back and forth between what?

How can a hydrogen atom, which has only one electron, create so many spectral lines?

In Bohr’s planetary model of the atom, what does the principal quantum number represent?

Which color of light comes from a greater energy transition: red or blue?

How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?

What might the spectrum of an atom look like if the atom’s electrons were not restricted to particular energy levels?

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 may rattle uncomfortably. How is this analogous to the quantized energy levels of an electron in an atom?

Does a shell have to contain electrons in order to exist?

Place the proper number of electrons in each shell:

Use the shell model to explain why a potassium atom, K, is larger than a sodium atom, Na.

Neon, Ne (atomic number 10), cannot attract any additional electrons. Why?

Use the shell model to explain why a lithium atom, Li, is larger than a beryllium atom, Be.

If matter is made of atoms, and atoms are made of subatomic particles, what comes together to create subatomic particles? Where might you find such information?

Astronomical measurements reveal that about 90% of the mass of the universe is invisible to us. This invisible matter, also known as dark matter, is likely to be “exotic” matter—very different from the elements that make up the periodic table (see Section 28.4). We know the dark matter is there because of its gravitational effects, but scientists can only guess as to its nature. What do you think dark matter might be made of? How soon might we know the answer?

In 2011, China was the leading producer of rare-earth metals, such as neodymium. controlling about 95% of the market. When China then tried to take financial advantage of this near-monopoly, it didn’t work. Why not?

Where on Earth might be a good place to find concentrated amounts of lithium salts?