CHM1020 (Chemistry) Ch. 3 Study Guide

Select the correct symbol and units for wavelength.

/\ and nm

Place the steps for drawing a Lewis structure in the correct order, starting with the first step at the top of the list.

1. Count the number of outer electrons contributed by each atom. 2. Add the valence electrons contributed by each individual atom to determine the total number of outer electrons for the species. 3. Arrange the outer electrons in pairs around the contributing atoms. 4. Ensure that each atom has a full outer shell.

Place the layers of the atmosphere in the correct order, starting with the layer that is farthest from the Earth at the top of the list.

1. Mesosphere 2. Stratosphere 3. Troposphere

Rank the following types of radiant energy in order of increasing frequency. Start with the radiation that has the lowest frequency at the top of the list.

1. Microwave 2. Infrared 3. Visible 4. Ultraviolet

Rank the following types of bonds from the longest to the shortest, starting with the longest bond at the top of the list.

1. Single covalent bond 2. Double covalent bond 3. Triple covalent bond

Place the following types of electromagnetic radiation in order of increasing wavelength (shortest at the top to longest at the bottom).

1. X-ray 2. UV radiation 3. Visible light 4. IR radiation 5. Radiowaves

1 nm (nanometer) = ________.

10^-9 m

The octet rule states that when atoms bond they may lose, gain, or share electrons in order to attain an outer level containing ________ electrons.

8

Which of the following options correctly describe the UV Index?

A UV Index color-coded yellow indicates a moderate level of UV radiation. The UV Index is based on the length of time required for skin damage to occur.

Which of the following options correctly describes how H2O and N2O can cause ozone to break down in the stratosphere?

Both species form free radicals, which react with O3 to form O2.

Which of the following options correctly describe potential biological effects of UV radiation in addition to skin cancer?

Exposure to UV radiation can cause retinal damage. Harmful UV radiation could have an effect on the carbon dioxide balance of our planet.

True or false: Resonance forms are different possible structures for the same species that interconvert rapidly.

False. No individual resonance form actually exists and there is no interconversion between forms. Rather the true structure is a single structure that is an average of all possible resonance forms.

Match each type of formula with the correct representation.

I-----I = Structural formula I2 = Chemical formula

Resonance forms are correctly defined as ________.

Lewis structures for the same species that differ in the placement of electrons

Which of the following statements correctly describe a Lewis structure?

Lone pairs are shown as pairs of dots on individual atoms. Bonding electrons are shown as lines or pairs of dots between two atoms.

What is the correct term used to describe the species HF, in which electrons are shared between H and F?

Molecule

What type of clouds are composed of tiny icy crystals formed from a small amount of water vapor present in a specific region of the atmosphere?

Polar stratospheric clouds

Which color visible light will have the lowest energy photons?

Red

What is the term used to describe a condition in which a dynamic system has no net change in concentration of the major species involved?

Steady state

Which of the following factors cause an increase in ozone production?

Sun directly overhead Sun closer to the Earth Increased intensity of UV radiation

Why is ozone depletion greater over the South Pole than the Arctic?

The air above the North Pole is not as cold, so that fewer polar stratospheric clouds form.

Energy is quantized. What does this mean?

There is a basic unit of energy that cannot be subdivided further.

What type of radiation can break chemical bonds?

UV radiation

Which of the following statements correctly describe the factors that influence the development of skin cancer in individuals?

UV-A is the form of UV radiation most strongly linked with skin cancers. People with light-colored skin are more prone to melanoma.

Match the type of radiant energy with the percentage of total energy emitted by the Sun.

Visible radiation = 39% IR radiation = 53% UV radiation = 8%

Which coefficients are needed to balance the simplified chemical equation representing the formation of ozone? energy + aO2 ----> bO3

a = 3 b = 2

A nanometer is one ________ of a meter.

billionth (1 nm = 1 x 10^-9 m)

We describe the "speed of light" as the speed at which light and other forms of radiation travel through a vacuum. This quantity, which is equal to 3.00 x 10^8 m/s, is given the symbol ________.

c

The bond formed between two nonmetals is called a ________ bond. This bond involves the ________ of one or more electron pairs between the two atoms.

covalent; sharing

A highly reactive species with one or more unpaired electrons is called a ________.

free radical

Exposure to UV radiation causes the concentration of melanin in the skin to ________.

increase

According to the relationship E = hc/ /\, energy and wavelength are ________ related. Therefore, the shorter the wavelength the ________ the energy of the radiation.

inversely; greater

A catalyst ________.

is typically regenerated during the reaction undergoes no permanent change during a reaction

On average, the concentration of stratospheric ozone at the equator is ________ than at the poles.

lower

The skin pigment responsible for darkening of the skin due to UV exposure is called ________.

melanin

In general ozone (O3) is much ________ reactive than oxygen (O2).

more

A designated region in the stratosphere of maximum O3 concentration is called the ________ layer.

ozone

Electromagnetic radiation consists of particles called ________, each of which has a discrete amount, or quantum, of energy. However, since electromagnetic radiation also has wave properties, each particle is also characterized by a specific ________ and frequency.

photons wavelength

The process by which green plants convert sunlight into stored chemical potential energy by producing glucose and oxygen is called ________.

photosynthesis

The maximum concentration of ozone in the atmosphere is found in the ________.

stratosphere

UV-C radiation has the highest energy of all the types of radiation but it is not biologically damaging because it never reaches the Earth. UV-C radiation is instead absorbed in the ________ by oxygen and ________.

stratosphere; ozone

Some UV radiation is beneficial to humans because UV-B light stimulates the production of ________, which is important for healthy bones and immune systems.

vitamin D