Chem Chapter 3 homework

Which of the following statements correctly describes a photon? A. A photon with a short wavelength has low energy B. A photon is a particle of electromagnetic radiation. C. Matter cannot absorb or emit a fraction of a photon D. All photons have the same amount of energy

*A photon is a particle of electromagnetic radiation *Matter cannot absorb or emit a fraction of a photon

A covalent bond:

*Involves the sharing of electrons between two atoms *Involves the attraction between the nucleus of each atom and the electrons of the other. *Electrons in a covalent bond are common property to both atoms that make up the bond.

During photosynthesis _______.

*Sunlight is converted into stored chemical potential energy *CO2 and H2O are consumed to produce stored glucose

Describe the UV index:

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

Facts of different types of UV radiation:

*The wavelength of UV-B radiation ranges from 280-320nm *UV-C radiation has the shortest wavelength *UV-A is the least damaging to the Earth's Surface

What is the order for the reaction of a CFC molecule with the stratospheric ozone?

1) A CFC molecule is bombarded with UV light releasing a chlorine radical. 2) Chlorine radicals react with ozone to produce CIO. and oxygen. 3) CIOO. decomposes to a chlorine radical and oxygen.

Place the steps taken to reduce the depletion of the ozone layer in chronological order, starting with the first step at the top of the list.

1) United Nations Environmental Program: World Plan of Action on the Ozone Layer 2) Vienna Convention on the Protection of the Ozone Layer 3) Montreal Protocol 4) Complete stoppage of production of CFCs in developing nations

How many valence electrons does each element have?

C - 4 Be - 2 Ne - 8 F - 7

Which of the following radicals are responsible for ozone depletion by CFC?

CIO. & Cl.

CFCs always contain _____.

Chlorine, Carbon, Fluorine

For an electron to "jump" from a lower energy level to a higher one, energy must be emitted by the electron. True or False?

False: For an electron to move from a lower-energy to higher-energy state, energy must be absorbed, not emitted.

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

MORE

Which allotrope of oxygen whose bonds can be broken by UV-B radiation?

O3 - Ozone

The pair of electrons involved in a covalent bond is called a(n) _________ electron pair, whereas the electrons not involved in bonding are called an unshared or _________ pair.

Shared/bonding ; lone/nonbonding

Which of the following is a common ingredient in mineral-based sunblock formulations?

TiO2 (Titanium dioxide) & ZnO (Zinc oxide)

True or False: CFCs are inert, nontoxic compounds

True - This is why they were chosen as refrigerants and fire suppressants

Rank the three types of UV radiation in order of increasing wavelengths, starting with the shortest wavelength radiation at the top of the list.

UV-C , UV-B, UV-A

Which of the following regions of the electromagnetic spectrum have sufficient energy to break covalent bonds?

X-ray and Ultraviolet

Ozone in our atmosphere is important because it...

absorbs some UV radiation

A substance that participates in a chemical reaction but is regenerated so that it undergoes no permanent change is called a(n) ________

catalyst

The bond formed between two NONMETALS is called a(n) ________ bond. This bond involves the _______ of one or more electron pairs between the two atoms.

covalent; sharing

Replacing halogen atoms (such as Cl) in CFCs with hydrogen results in a(n) ________.

decrease in molar mass & decrease in boiling point

Lewis structures are used to represent covalent compounds. Shared electron pairs are shown either as pairs of _______ or lines and only _______ electrons are shown.

dots; valence/outer

The speed of a wave is determined by multiplying the ______ of the wave by its wavelength. In a vacuum all electromagnetic radiation travels at a constant speed: _______m/s.

frequency; 3.00x10^8

For the main-group elements (1, 2, etc.) the number of valence electrons for an element is equal to the ______ number for the element.

group

Introducing too many Cl atoms into a potential replacement for CFCs causes a(n) ______ in flammability and a(n) _____ in boiling point.

increase; increase

Wavelength and frequency are ________ proportional to each other. As wavelength increases frequency will ______.

inversely; decrease

Select the correct symbol and units for wavelength. More than one unit and/or symbol may be correct.

nm, "lambda"

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

photon , wavelength/energy

Greek symbol for FREQUENCY

v

The distance a wave travels during one cycle is called its _________. This is usually measured as the distance between two ________ or two troughs.

wavelength; peak/crests