Atoms & Molecules, Measurement And Units , Concentration

Front 1

What is the definition of an atom?

Back 1

The smallest chemical unit of matter

Front 2

What is the definition of a molecule?

Back 2

Two or more atoms linked together to make a substance with unique properties

Front 3

What is the definition of concentration?

Back 3

The quantity of a substance within a certain volume.

Front 4

Fifty grams of carbon disulfide can be broken down into 42.1 grams of sulfur and 7.9 grams of carbon.
Is carbon disulfide made up of atoms or molecules?

Back 4

Carbon disulfide is made up of molecules.
Since it can be broken down into smaller components, it must be made of molecules.

If it were made of atoms, it could not be broken down into smaller units, not correct to say carbon disulfide is made of atoms.

Remember, a molecule has properties that are unique. Thus, no atom has the properties of carbon disulfide.

Only carbon disulfide molecules have the properties of carbon disulfide, so it is made of molecules.

Front 5

If you put iron near a magnet, the iron will be attracted to the magnet. Rust is made up of molecules that contain iron atoms and oxygen atoms. Rust is not attracted to a magnet. If rust contains iron atoms, and iron is attracted to a magnet, why isn't rust attracted to a magnet?

Back 5

Rust is not attracted to a magnet because when an atom is a part of a molecule, the molecule does not take on the characteristics of the atom.

Instead, the atoms in the molecule join together in such a way as to give the molecule its own unique characteristics.

Front 6

A statue is made out of copper and displayed outside. After many years, what color will the statue be?

Back 6

The statue will eventually turn a shade of green, just like the copper wire did in Experiment 1.1.

This comes from the copper atoms reacting with water and carbon dioxide in the air to make copper hydroxycarbonate.

Front 7

Have scientists actually seen atoms?

Back 7

Scientists have NOT seen atoms. The scanning tunneling electron microscope "pictures" that you see are not pictures of atoms.

Instead, they are the result of computer calculations involving electricity and a theory called quantum mechanics.

Front 8

Give the numerical meaning for the prefixes "centi", "milli," and "kilo".

Back 8

centi means 0.01

milli means 0.001

kilo means 1,000

Front 9

If you wanted to measure an object's mass, what metric unit would you use?

What English unit would you use?

Back 9

Mass is measured in grams in the metric system.

In the English system, it is measured in slugs.

Front 10

If you wanted to measure an object's length, what metric unit would you use?

What English unit would you use?

Back 10

Length is measured in meters in the metric system.

In the English system it is measured in yards, inches, feet and miles.

Front 11

How many centimeters are in 1.3 meters?

Back 11

130 cm

Front 12

If a person has a mass of 75 kg, what is his mass in grams?

Back 12

75,000 g

Front 13

How many liters of milk are in 0.5000 gallons of milk? (1 gal = 3.78 L)

Back 13

1,89 L

Front 14

A meter stick is 100.0 centimeters long. How long is it in inches?
(1 inch = 2.54 cm)

Back 14

39.4 inch

Front 15

Ozone is a poisonous gas that can build up in the air in dense cities. Thus, there are many environmental initiatives to lower the amount of ozone in the air we breathe. One way you can make ozone, however, is by baking bread. The nice smell you associate with baking bread is actually due, in part, to ozone. If ozone is poisonous, why is baking bread not considered a dangerous activity?

Back 15

Baking bread is not a dangerous activity because the ozone it produces is not concentrated enough to be dangerous. Ozone is a poison, but at low enough concentrations, it does not adversely affect people. At higher concentrations, however, it can be toxic enough to kill you.

Front 16

Sulfur is a yellow powder that is composed of sulfur atoms. Sulfur dioxide is a colorless, poisonous gas that contains sulfur atoms. Is sulfur dioxide composed of atoms or molecules.

Back 16

Sulfur dioxide is composed of molecules. We can tell this because it does not have the properties of sulfur (a yellow powder) but we are told that it contains sulfur atoms. The only way an atom can give up its properties is to become a part of a molecule.

Front 17

While looking at historical grave markers, you find a statuette that is blue-green in color. In order to read the inscription, you scrub the surface of the statuette, and the blue-green color comes off a a fine powder. What color is the statue underneath?

Back 17

The statue will have a copper color underneath the green powder.
We learned from experiment 1.1 and the subsequent discussion that the green powder we see on statues and the like is copper hydoxycarbonate. This molecule needs copper to form. Thus, the statue must have copper on it in order for the copper hydroxycarbonate to have formed on it.

Front 18

A molecule is broken down into its constituent atoms. Do these atoms have the same properties as the molecules.

Back 18

The atoms do not have the same properties as the molecule.

When atoms join to make a molecule, their individual properties disappear and the molecule takes on its own, unique properties. When the molecule is broken down into its atoms, the atoms regain their individual properties.

Front 19

When salt is dissolved in water, it actually breaks down into two different substances. Is salt composed of atoms or molecules?

Back 19

Salt is composed of molecules.

Hint 19

Since atoms are the smallest chemical units of matter in creation, if salt can be broken into smaller parts, it must be made of atoms linked together. Thus, it is made of molecules. Now you might think that since molecules are made by linking atoms together, you could also ay that salt is made of atoms. However, that is not really correct. The atoms that link together to form salt molecules have their own, unique properties, but those properties completely disappear when the atoms join to form salt molecules. Thus, it is not the atoms that give the salt its properties, the molecules do.

Front 20

Muriatic acid is sold in hardware stores for use in cleaning. Pool owners, for example, use it to clean hard water stains and algae stains from their pools. Its active ingredient is hydrochloric acid. The Works is a toilet bowl cleaner with hydrochloric acid in a liter of muriatic acid , and there are approximately 30 grams of hydrochloric acid in a liter of The Works. Why is muriatic acid a more powerful cleaner than The Works?

Back 20

Muriatic acid is the more powerful cleaner because the active ingredient is more concentrated.

In the same amount of volume, muriatic acid has more than 10 times as much active ingredient. Since the active ingredient is more concentrated, it will clean better.

Front 21

Sodium is a necessary part of a healthy diet. If a person does not ingest enough sodium every day, that person will get sick and perhaps die. Nevertheless, some people try to limit their sodium intake by eating a low-salt diet. how can it b e good to limit your sodium intake, even through sodium is a necessary part of body chemistry.

Back 21

Sodium is necessary for the body at a certain concentration. If you eat too much sodium, you raise the concentration too much. In the same way, if you eat too little sodium, you lower its concentration too much. Either way, your body suffers. Thus, you need to keep the sodium concentration in your body at the right level. Too little sodium intake will reduce the sodium concentration to critical levels, while too much sodium intake will raise it to toxic levels.

Front 22

Suppose you left a glass of water outside on 2 different days. On the first day, it is warm and humid. On the second day, it is the same temperature, but the humidity is low. Each day, you measure how long it takes the water to completely evaporate from the glass. On which day will the time it takes the water to evaporate be the smallest?

Back 22

The water will take the least time to evaporate on the 2nd day.

Hint 22

Remember, when humidity is high, there is already a lot of water vapor in the air. Thus, water does not evaporate very quickly. On low humidity days, however, there is little water vapor in the air, so water evaporates quickly.

Front 23

Suppose you did the same experiment that was described in the previous question when the relative humidity was 100%. How quickly would the water evaporate from the glass?

Back 23

You will not see any evaporation from the glass of water.

Hint 23

When the relative humidity is 100%, no more water can go into the air, so no net evaporation can occur! Now it turns out that water will evaporate from the glass, but water will also condense back into the glass from the air. The rate at which the water evaporates will equal the rate at which it condenses, however, so no net evaporation will occur.

Front 24

If a scientist were to measure the percentages of nitrogen and oxygen in a sample of air that was not dry, would they be greater than, less than, or essentially the same as the percentages shown in fig. 2.1

Back 24

The percentages of nitrogen and oxygen would be less.

Hint 24

Think about this one. If there is water in the air, then the total amount of molecules in the air is greater. Well, the percentage of a substance is equal to the amount of that substance divided by the total amount in the mixture times 100. If you just add water vapor to the mixture of gases, you have not increased the amount of nitrogen, for example. Thus, the amount of nitrogen stays the same. However, the total amount of molecules in the mixture increases, because you added water molecules. As a result, when you calculate the percentage, you take the same number for the amount of nitrogen, but you divide by a larger number (for the amount of molecules in the mixture) As a result, the percentage of nitrogen goes down.

Front 25

At high altitudes, there is less air around you as compared to lower altitudes. Would a candle at high altitudes burn dimmer, brighter, or essentially the same as the same candle at low altitudes?

Back 25

The candle would burn dimmer.

Hint 25

If there is less air around you, there is also less oxygen around you, there is also less oxygen around you. With less oxygen, the fire will burn more slowly, making the candle dimmer.

Front 26

We know that if the carbon dioxide concentration were too low, plants would starve. Conversely, experiments indicate that many plants actually flourish when the concentration of carbon dioxide in their vicinity increases. How can this fact help explain why some experiments indicate that houseplants tend to grow better when their caretakers talk to them?

Back 26

Plants may grow better when their caretakers talk to them because when someone talks to a plant, he exhales some carbon dioxide on it.

Hint 26

This increases the concentration of carbon dioxide in the plant's vicinity, which might make some plants grow better.

Front 27

Atoms are the_____________unit of matter. They are so_________that you cannot see them. Images of atoms produced by scanning tunnerling electron microscopes are not pictures, but are the result of computer________. Such images are part of the large amount of________evidence that indicates atoms exist. When two or more atoms link together, they form a _________, which has its own unique properties.

Back 27

smallest
small
calculations
indirect
molecule

Front 28

When a substance is made of billions and billions of the same atom, it is called an____, while substances, made up of billions and billions of the same molecule are called_____. Some substances, called_______,are made of more than one kind of atom or molecule. In Experiment 1.1, you watched the molecle know as_____break down into two elements:__________and______. In addition, you saw the_______in the wire (an element) react with _______ molecules to make copper hydroxycarbonate.

Back 28

element
compounds]
mixtures
water
hydrogen and oxygen
copper
baking soda

Front 29

When making measurements, the ____we report are just as important as the numbers. The base metric unit for weight is the ____while the base English unit for weight is the____. Although the weight of an object varies depending on gravity, the____does not.

Back 29

units
gram
slug
Newton
pound
mass

Front 30

The base metric unit for length is the____, and the base English unit for length is the_____. The base metric unit for volume is the_____, and the base English unit for volume is the______.

Back 30

meter
foot
liter
gallon

Front 31

In the metric system, prefixes govern the____of a unit. The "milli" prefix mans____while the ____prefix means 0.01. The "kilo" prefix means_____. Thus, an object with a mass of 1 centigram has____mass than an object with a mass of 1 kilogram.

Back 31

size
0.001
centi
1,000
less

Front 32

The metric unit for temperature is degrees_____. This unit uses no prefixes. In the this system, water freezes at____and boils at_____.

Back 32

Celsius
0 degrees Celcius
100 degrees Celsius

Front 33

In the Old Testament, a measurement unit for length called the___was used.

Back 33

cubit

Front 34

Concentration is the___substance within a certain____. At certain concentrations, chemicals behave___. At other concentrations, those same chemicals can behave____. Vitamins, for example, are____for our body at low concentrations but they become____at high concentrations. In Experiment 1.3 the more concentrated the vinegar, the___the antacid table disappeared

Back 34

quantity
volume
behave in one way
behave in a different way
very good
toxic
faster

Front 35

In this course, we do conversions using___method, in which the measurement you want to convert is multiplied by a fraction that contains both the original unit and the unit you want to convert to.

Back 35

factor-label

Front 36

Is the air cleaner today, or was it cleaner 30 years ago?

Back 36

The air is much cleaner today than 30 years ago.

Front 37

What is a cost/benefit analysis?

Back 37

A cost/benefit analysis attempts to determine whether or not to take an action by determining the benefits of that action as well as the cost. If the benefit outweighs the cost, the action should be taken. If not, the action should not be taken.

Front 38

What does a catalytic converter do in a car?

Back 38

It converts carbon monoxide in the car's exhaust to carbon dioxide.

The fact that most cars have these today is one of the main things responsible for reducing the carbon monoxide concentration in the air by more than 70% since3 1975.

Front 39

What does a scrubber do in a smokestack?

Back 39

A scrubber traps sulfur oxides in a smokestack and keeps them from being emitted into the air. They are one of the reasons there has been more than 70% decrease in sulfur oxides concentration in the air.

Front 40

In the United States, many regulations are aimed at decreasing the amount of ground-level ozone in the air, because ground-level ozone is considered a pollutant. At the same time, many regulations are aimed at increasing the amount of ozone in the ozone layer. Despite the fact that ozone in the ozone layer is the same as ground-level ozone, ozone in the ozone layer is not considered a pollutant. Instead, it is considered an essential substance. Why?

Back 40

Ground-level ozone is a pollutant because it is a poison, and it is where we can breathe it. Ozone in the ozone layer is not a pollutant because no one breathes that high up in the air, so it is poisonous properties are unimportant. It is necessary in the ozone layer in order to block the sun's ultraviolet rays.