Chemistry 2019-2020 Supplemental Opportunities for Enrichment & Review

Resources Needed: PDF Access to worksheets (Available for pickup at school and/or online via Google Classroom. Chemistry: Matter and Change McGraw Hill Textbook Optional Online/App Textbook Access: The Phone App (ConnectEd from McGrawHill) and an Online Version of the Textbook can be accessed via this link: https://connected.mcgraw-hill.com/connected/login.do To get a copy of your username and password please contact your teacher Team members: John Daley ( jdaley@sedelco.org ) - Kevin Greto ( kgreto@sedelco.org)

Science March 30

Review

March 31 st

Review

April 1st

Review

April 2nd

Enrichment

April 3rd

Enrichment

Assignment:

Physical and

Chemical

Changes

Worksheet

Assignment:

History of the

Atom

Assignment:

Isotopes

Assignment:

Readworks EMR

Assignment:

Light in the Dark

3/30/20 - Review Chapter 3 Section 2 on Physical and Chemical Changes and complete the Physical and Chemical Changes Worksheet (1 page) 3/31/20 - Review Chapter 4 Section 1 about the History of the Atom and complete the History of the Atom Timeline Worksheet (2 pages) 4/1/20 - Review Chapter 4 Section 3 about How atoms differ and complete the Isotopes of an Element Worksheet (1 page) 4/2/20 - Enrichment: Read and Complete the Readworks.org assignment on Electromagnetic Radiation (5 pages) 4/3/20 - Enrichment: Complete the Lighting the Dark at home Activity (2 pages)

Name _________________________________________ Date _________________ Class _________________

Physical and Chemical Changes

Chemistry Challenge Problems • Physical and Chemical Changes

3

hysical and chemical changes occur all around us. One of the many places in which

physical and chemical changes occur is the kitchen. For example, cooking spaghetti in a

pot of water on the stove involves such changes. For each of the changes described below, tell

(a) whether the change that occurs is physical or chemical, and (b) how you made your choice

between these two possibilities. If you are unable to decide whether the change is physical or

chemical, tell what additional information you would need in order to make a decision.

1. As the water in the pot is heated, its temperature rises.

2. As more heat is added, the water begins to boil and steam is produced.

3. The heat used to cook is produced by burning natural gas in the stove burner.

4. The metal burner on which the pot rests while being heated becomes red as its

temperature rises.

5. After the flame has been turned off, a small area on the burner has changed in color from

black to gray.

6. A strand of spaghetti has fallen onto the burner, where it turns black and begins to

smoke.

7. When the spaghetti is cooked in the boiling water, it becomes soft.

P

Name: _________________________________ Date: __________ Class: _______

John Dalton (1766 – 1844):

John Dalton was an English chemist. His ideas form the atomic theory

of matter. Here are his ideas.

All elements are composed (made up) of atoms. It is impossible

to divide or destroy an atom.

All atoms of the same elements are alike. (One atom of oxygen

is like another atom of oxygen.)

Atoms of different elements are different. (An atom of oxygen is different from an atom of hydrogen.)

Atoms of different elements combine to form a compound. These atoms have to be in definite whole number ratios.

For example, water is a compound made up of 2 atoms of hydrogen and 1 atom of oxygen (a ratio of 2:1). Three atoms

of hydrogen and 2 atoms of oxygen cannot combine to make water.

1. What is the name of John Dalton’s theory? ________________________________________________________

2. What are elements made of? ____________________________________________________________________

3. An atom of hydrogen and an atom of carbon are ____________________________________________________

4. What are compounds made of? __________________________________________________________________

5. The ratio of atoms in HCl is: a) 1:3 b) 2:1 c) 1:1

6. The ratio of atoms in H2O is: a) 1:3 b) 2:1 c) 1:1

J. J. Thompson (Late 1800s):

J. J. Thompson was an English scientist. He discovered the electron when he was experimenting with gas discharge tubes. He noticed a movement in a tube. He called the movement cathode rays. The rays moved from the negative end of the tube to the positive end. He realized that the rays were made of negatively charged particles – electrons.

1. What did J.J. Thompson discover? __________________________________________________________________________

2. What is the charge of an electron? _________________________________________________________________________

3. What are cathode rays made of? ___________________________________________________________________________

4. Why do electrons move from the negative end of the tube to the positive end? _____________________________________________

5. What was Thompson working with when he discovered the cathode rays? _________________________________________________

Lord Ernest Rutherford (1871 – 1937):

Ernest Rutherford conducted a famous experiment called the gold foil experiment. He used a thin sheet of gold foil. He also used special equipment to shoot alpha particles (positively charged particles) at the gold foil. Most particles passed straight through the foil like the foil was not there. Some particles went straight back or were deflected (went in another direction) as if they had hit something. The experiment shows:

Atoms are made of a small positive nucleus; positive nucleus repels (pushes away) positive alpha particles

Atoms are mostly empty space

1. What is the charge of an alpha particle? ___________________________________________________________________________

2. Why is Rutherford’s experiment called the gold foil experiment? __________________________________________________________

3. How did he know that an atom was mostly empty space? _______________________________________________________________

4. What happened to the alpha particles as they hit the gold foil? ___________________________________________________________

5. How did he know that the nucleus was positively charged? ______________________________________________________________

Niels Bohr (Early 1900s):

Niels Bohr was a Danish physicist. He proposed a model of the atom that is similar to the model of the solar system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy levels – a certain distance from the nucleus. Each energy level can hold a certain number of electrons. Level 1 can hold 2 electrons, Level 2 - 8 electrons, Level 3 - 18 electrons, and level 4 – 32 electrons. The energy of electrons goes up from level 1 to other levels. When electrons release (lose) energy they go down a level. When electrons absorb (gain) energy, they go to a higher level.

1. Why could Bohr’s model be called a planetary model of the atom? ___________________________________________

2. How do electrons in the same atom differ? _________________________________________________________________

3. How many electrons can the fourth energy level hold? _____________________________________________________

4. Would an electron have to absorb or release energy to jump from the second energy level to the third energy level?

__________________ And for an electron to fall from the third energy level to the second energy level? ________________ energy.

Name _________________________________________ Date _________________ Class _________________

Isotopes of an Element

Chemistry Challenge Problems • Isotopes of an Element

4

mass spectrometer is a device for separating

atoms and molecules according to their mass.

A substance is first heated in a vacuum and then

ionized. The ions produced are accelerated through a

magnetic field that separates ions of different masses.

The graph below was produced when a certain

element (element X) was analyzed in a mass

spectrometer. Use the graph to answer the

questions below.

1. How many isotopes of element X exist?

2. What is the mass of the most abundant isotope?

3. What is the mass of the least abundant isotope?

4. What is the mass of the heaviest isotope?

5. What is the mass of the lightest isotope?

6. Estimate the percent abundance of each isotope shown on the graph.

7. Without performing any calculations, predict the approximate atomic mass for element

X. Explain the basis for your prediction.

8. Using the data given by the graph, calculate the weighted average atomic mass of

element X. Identify the unknown element.

A

Electromagnetic Radiation

Electromagnetic Radiation

What are we looking at when we look at objects? When you look at a basketball, what are you seeing? You’re seeing a collection of colors, lines, textures, and shapes. There are many ways to think about how we perceive the information our eyes take in from the outside world. Science tells us that light is the reason we are able to see objects. Without light, we wouldn’t be able to process the visible world. And the light that allows us to see isn’t just the stuff that comes from light bulbs in our homes and schools. Light is a form of electromagnetic radiation made of electromagnetic waves. Electromagnetic radiation is a stream of photons that travels in a wave-like pattern, carrying energy, and moving at the speed of light. The electromagnetic spectrum is the range of all types of electromagnetic radiation, including visible light, infrared light, ultraviolet light, X-rays, and gamma rays. Our eyes are capable of seeing only a small portion of the electromagnetic spectrum. So there are plenty of waves being expressed by the physical world that we simply don’t get to see. On the electromagnetic spectrum, you will see that there are all different types and intensities of waves. The electromagnetic spectrum is organized in order of wavelength. There are different types of light, each with a different length of wave. Some of these waves are scrunched together, like a closed slinky. Other waves are stretched far apart, like a slinky that is stretched between opposite ends of a room.

© 2013 ReadWorks®, Inc. All rights reserved.

Electromagnetic Radiation The portion of the spectrum that our eyes are sensitive to—called visible light—is smack dab in the middle of the spectrum. The spectrum’s far ends include electromagnetic radiation with scrunched together waves—gamma rays and X-rays—and stretched out waves, such as radio waves and microwaves. If our eyes were capable of seeing every type of wave on the electromagnetic spectrum, a commonplace sight like your school cafeteria would look completely chaotic! You would see microwaves, radio waves—different types of electromagnetic energy—bouncing off practically every surface. And that’s just within the known spectrum. Scientists imagine that the spectrum goes on forever, with infinite types of waves. There even may be some waves we cannot sense at all. The waves emitted by our physical world make it possible for us to communicate over vast distances, see objects in the dark that are deep beneath the surface of the earth and sea, and even look deep into outer space. By studying electromagnetic waves and creating tools that help us gain access to a wider portion of the electromagnetic spectrum, humankind has given itself unique powers for collecting information about our world. We can think of the waves as a kind of ongoing message being sent out by the universe, one to which we have only limited natural access. Many of the tools mankind has invented over time to harness the information contained within electromagnetic radiation are present in your home or school every day, including televisions and and radios. Other tools like night-vision goggles are also examples of technology that gives us superhuman access to wave frequencies further toward the ends of the known spectrum. Even without special tools and machines, however, our eyes’ sensitivity to light makes it possible for us to see beautiful things—that bouncing basketball; a tall, vivid rainbow after a storm; the faces of our friends and families. If it weren’t for the way our eyes and brain are able to create comprehensible images from waves of visible light, it would be very difficult for us to understand the messages emitted by our physical universe.

© 2013 ReadWorks®, Inc. All rights reserved.

Questions: Electromagnetic Radiation

Name: Date: 1. What allows people to see objects?

A radio waves B glass C x-rays D light

2. What does the author list in the passage?

A different types of electromagnetic spectrums B different types of electromagnetic radiation C scientists who study electromagnetic radiation D the differences between radio waves and microwaves

3. We can think of electromagnetic waves as a kind of ongoing message being sent out by the universe. Humans are able to naturally access only a portion of this message. What information from the passage best supports this statement?

A Mankind has invented tools to harness the information contained within electromagnetic radiation.

B The waves emitted by our physical world make it possible for us to communicate over vast distances.

C Without light, we wouldn’t be able to process the visible world. D The human eye is only sensitive to a portion of the electromagnetic spectrum.

4. Based on the passage, what can be concluded about the ability of humans to see X-rays and gamma rays?

A Humans cannot see X-rays and gamma rays. B Humans can see X-rays and gamma rays. C Humans can see X-rays but not gamma rays. D Humans can see gamma rays but not X-rays.

© 2013 ReadWorks®, Inc. All rights reserved.

1

Questions: Electromagnetic Radiation

5. What is the passage mainly about?

A why waves have different wavelengths B electromagnetic waves and how humans utilize them C different tools humans have invented to harness information D gamma rays and x-rays

6. Read the following sentence: “When you look at a basketball, what are you seeing?” Why might the author have started the passage with this question?

A because the main idea of the passage is about basketball B to show how important the color orange is to electromagnetic waves C because the author wants to use the example of basketball to explain

electromagnetic radiation D to give the reader an object to visualize before examining the role of light

7. Choose the answer that best completes the sentence below. Humans have invented many tools that allow us to access a wider portion of the electromagnetic spectrum. _______, humankind has given itself unique powers for collecting information about the world.

A As a result B However C Since D Although

8. What is electromagnetic radiation? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

© 2013 ReadWorks®, Inc. All rights reserved.

2

Questions: Electromagnetic Radiation

9. According to the passage, what are televisions, radios, and night-vision goggles all examples of? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 10. Why might humans want to gain access to a wider portion of the electromagnetic spectrum? Use information from the passage to support your answer. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

© 2013 ReadWorks®, Inc. All rights reserved.

3

Name _________________________________________ Date _________________ Class _________________

Lighting the Dark

Real-World Chemistry • Lighting the Dark

13

Background

Background

Background

he invention of artificial lighting systems thousands of years ago

transformed human civilization. Instead of restricting their activities to

daylight hours, humans could remain active as late into the night as they

wanted. And they could explore areas of darkness, such as caves, with the aid

of their artificial lights.

At first, artificial lighting systems consisted of little more than sticks dipped

into tar and set on fire. By 1800, the Scottish inventor William Murdock had

developed a lamp that burned gas, and, before long, city dwellers throughout

the civilized world had their own source of light. However, by the early

twentieth century, many lighting systems were designed to operate on

electricity.

Incandescent Lamps

The first widely successful electric light was

the incandescent light, invented by Thomas

Alva Edison in 1879. The term incandescent

refers to an object that gives off light because it

is heated. In an incandescent lamp, a wire

filament is heated, begins to glow, and gives

off both heat and light. Incandescent lights are

now widely used, but they are not a very

efficient way to produce artificial light. Less

than ten percent of the electrical energy that

enters an incandescent light bulb is transformed

into light. The remaining 90 percent is

converted to heat.

Neon Lamps

In the 1910s, the French chemist Georges

Claude found another method for producing

artificial light. Claude passed an electric current

through a tube filled with a noble gas and found

that the tube gave off a glow. This discovery

marked the beginning of the lights we now

know as neon lights. Many neon lights do, in

fact, contain neon gas, but others contain

different noble gases, such as argon, krypton, or

xenon. Each of these gases gives off a

distinctive color when electrical energy is

passed through it. Thus, when you see a

dramatic display of multicolored neon lights,

each of the tubes contains a different gas.

Fluorescent Lamps

By the 1930s, scientists found that the inside

surface of a neon lamp could be coated with a

phosphorescent material that glows when

struck by energy. Thus the fluorescent lamp

was born. In a fluorescent lamp, an electric

current flows from one end of the tube to the

opposite end, exciting the mercury, argon, or

krypton gas atoms within the tube. The energy

given off by the excited gas atoms strikes the

phosphor coating on the lamp, and the coating

gives off a glow. The color of the glow depends

on both the gas inside the lamp and the material

used to coat the inside of the tube. Because

most of the electrical energy supplied to them is

converted to light, and relatively little to heat,

fluorescent lamps are much more efficient than

incandescent lamps.

Compact Fluorescent Lamps

The compact fluorescent lamp (CFL) was

invented by Edward Hammer, an engineer, in

1976. Due to difficulty in manufacturing the

lamp, CFLs were not commercially available

until the early 1980s. They are designed

T

Name _________________________________________ Date _________________ Class _________________

Lighting the Dark CONTINUED

Real-World Chemistry • Lighting the Dark

14

to replace incandescent lamps and can fit into

existing incandescent light fixtures. Compact

fluorescent lamps are very popular because

they use about one-quarter of the power of

incandescent lamps of similar light output.

CFLs also have an average lifespan between 8

and 15 times that of incandescent lamps. CFLs

cost more than incandescent lamps, but the

increase in cost is recovered in energy savings

and replacement costs over the bulb’s lifetime.

However, like all fluorescent lamps, CFLs

contain mercury. This makes safe disposal of

CFLs complicated and causes a health risk if

the lamp breaks.

Other Types of Lamps

Many variations on the incandescent and

fluorescent lamp, as well as entirely different

lamps, are available today. For example, an

infrared lamp is a type of incandescent lamp

that releases most of its energy in the infrared

portion of the electromagnetic spectrum. This

variation is achieved by modifying the

temperature of the filament in the lamp.

Whereas the filament in a typical 500-watt

lamp is heated to about 2960 K, the filament in

an infrared heat lamp is heated to only 2000 K.

Infrared heat lamps are used for many

purposes, such as drying paint, heating farm

buildings, and treating muscles strains.

An ultraviolet lamp is a variation of a

fluorescent lamp in which visible light is

filtered out and only radiation in the ultraviolet

portion of the spectrum (so-called “black

light”) is emitted. Lamps of this design are used

for dramatic effect in advertising and

decoration, as sunlamps, to destroy bacteria,

and for the analysis of engineered products.

Some older forms of lamps now have only

limited applications. For example, the carbon

arc lamp, invented by Sir Humphry Davy in

1805, once had many industrial uses. The lamp

operates by passing an electric current between

two carbon electrodes. The electric current

excites the gas between the two electrodes. The

light given off comes partly from the excited

gas molecules and partly from the glow of the

hot carbon electrodes. Although carbon arc

lamps have been largely replaced by high-

intensity mercury vapor lamps, they are still

used in projectors and searchlights, and in the

fields of photography and scientific research.

Activity

What types of lighting systems do you

encounter in your everyday life? Conduct a

survey by making note of every light bulb or

other artificial light source that you see over a

three-day period. Make a table such as the one

shown below for the lamps you find. If you

discover a type of lamp not described above,

refer to an encyclopedia or a physics textbook

for further information about the operation and

uses of the lamp.

Sample Report Form

Type of Lamp Location(s) Purpose(s)* Advantage(s)

Incandescent Rooms at home Inexpensive, easy to change,

provides sufficient light

*Indicate any purpose other than or in addition to providing light, such as for advertising, decoration,

providing heat, and so on.