Chem100: Chapter 2 Quiz

How many total electrons and how many valence electrons are in an atom of potassium, K?

19 and 1

Which one of the following lists gives the correct number of outermost (valence) electrons for atoms of Ca, Si, and F?

2, 4, 7

UV-C, UV-B and UV-A radiation are respectively the bands of wavelengths.

<280 nm, 280-320 nm, 320-400 nm

CFCs (Freon 12 and Freon 11) a. are compounds that have properties that are ideal for use as refrigerants - such as in refrigerators and air conditioners of all types, propellants in aerosol cans, solvents for oil and grease, sterilizers for surgical instruments, and gases for blowing into some polymers to make expanded plastic foams. b. are nontoxic, nonflammable, cheap, and at one time widely available c. have had a major impact on the development and growth of the Southern areas of the U.S. d. All of the above

All of the above

CCl2F2 → · CClF2 + Cl · Focusing now on the chlorine atom shown above, Chlorine atoms... a. really have 7 electrons in the outer energy level even though only one is shown in the diagram. (Remember these are also called valence electrons.) b. have one unpaired electron in the set of 7 valence electrons and that is what the dot represents. c. chlorine atoms are very reactive as they achieve stability by forming an electron sharing relationship with another atom to acquired 8 electrons in its outer energy level. (The stable octet.) d. All of the above statements are true and therefore this is the best answer

All of the above statements are true and therefore this is the best answer

The goal of the Montreal Protocol in 1987 was to... a. reduce the amount of new production of chlorofluorocarbons in developed countries. b. recycle existing chlorofluorocarbons rather than release them into the air. c. encourage research into substitutes for chlorofluorocarbons. d. All of these choices are correct.

All of these choices are correct

What is the relationship between stratospheric levels of atomic chlorine and ozone?

As chlorine increases, ozone decreases

It is the _____ electrons that account for many of the chemical and physical properties of elements.

outermost

Less energy is required to break the bonds between the oxygen atoms of an _______ molecule than to break the bonds between the oxygen atoms of an _______ molecule and therefore ___________ radiation, which is of lesser energy than __________ radiation can break the bonds between the oxygen atoms of an ______ molecule.

ozone, oxygen, UV-B, UV-C, ozone

When legislation is enacted to limit pollution based on what seems to be incomplete scientific evidence, we would say that the legislators are acting in accordance with the ___________.

precautionary principle

Which of the following gives the correct ranking from lowest energy on the left to highest on the right?

radio waves; infrared energy; UV energy; x-rays

The source of electromagnetic radiation (some being visible to the human eye) for the planet earth is

sun

CCl2F2 → · CClF2 + Cl · What is shown is a specific example of a general KEY reaction involving CFCs when UV-C is available. Giving it quick consideration shows

that two free radicals are formed, and one of them is a chlorine atom

The mass number of an element is

the sum of the number of protons and neutrons

Electromagnetic radiation travels from source to destination in a wave-like form and the distance between identical points on two different wave crests is called the

wavelength

HFCs may be used to replace CFCs. Which compound is a HFC?

CHClF2

A series of four reactions, known as the __________ cycle, are thought to explain how the naturally occurring happening of the ozone concentration remaining at a steady state occurs. (This will be referred to occasionally. Remember this is the "natural" condition.)

Chapman

Stratospheric ozone depletion means that the radiation of shorter wavelength than 320 nm will be screened out more effectively and less will reach the surface of the earth.

False

Which is the false information? a. Ozone, O3, is an odorless gas at room temperature. b. The concentration of ozone in the stratosphere exceeds the concentration of ozone in the troposphere by quite a significant amount. c. Oxygen exists normally at room temperature as a diatomic molecule and ozone under the same conditions exists as a triatomic molecule. d. Oxygen, O2, is an odorless gas at room temperature.

Ozone, O3, is an odorless gas at room temperature.

Which of the following is the true statement? a. The bonds between the oxygen atoms in an oxygen molecule, O2, are stronger than the bonds between the oxygen atoms in an ozone molecule, O3. b. The bonds between the oxygen atoms in an oxygen molecule, O2, are weaker than the bonds between the oxygen atoms in an ozone molecule, O3. c. The stronger the bond between oxygen atoms the less the amount of energy it takes to break it. d. Bonds between oxygen atoms in both O2 and O3 are of the same strength.

The bonds between the oxygen atoms in an oxygen molecule, O2, are stronger than the bonds between the oxygen atoms in an ozone molecule, O3.

How are energy, wavelength and frequency of electromagnetic radiation related?

The higher the energy of the radiation, the higher the frequency and the shorter the wavelength

What distinguishes one element from another?

The number of protons

The "ozone layer" is found

in the stratosphere

In the periodic table, which elements typically have similar properties?

Those in the same columns

Key to the reduction of chlorine atoms in the stratosphere is stopping the production of CFCs.

True

The major naturally occurring cause of ozone destruction, wherever it takes place around the globe, is a series of reactions involving water vapor and its breakdown products.

True

The smallest fraction of solar radiation above the atmosphere of the earth is

UV (Ultraviolet)

The most damaging UV band of radiation is

UV-C

The name and the abbreviation of the class of man-made compounds that are responsible for the depletion of ozone in the stratosphere are

chlorofluorocarbons, CFCs