Red, green and white fireworks bursting in the night sky over the Washington Monument and the Lincoln Memorial

CHEMISTRY · ATOMIC STRUCTURE

Atomic Spectra Virtual Lab

Follow along with your worksheet, one question at a time.

mrsajdak.com/spectra

Photo: National Park Service

BEFORE YOU START

Light from atoms

Bright glowing signs in many colors along a street in Las Vegas at night

City signs

Each glass tube is full of gas. Electricity makes the gas glow.

Green northern lights glowing in a dark sky over mountains and spruce trees

Northern lights

Energy from the Sun hits gas high in the air. The gas glows.

Words you will use

Energy level: a fixed place an electron can be.

Photon: a tiny packet of light.

Wavelength: the length of one wave of light, in nm.

Emission spectrum: the set of colors an element gives off.

Different gases glow different colors. Why? Can light tell you what a gas is?

Photos: Carol M. Highsmith, Library of Congress · NPS / Tim Rains

BEFORE YOU START

Get set up

The top of the lab page: the title Atomic Spectra, a picture of a lab bench with a power supply and a rack of gas tubes, and a Virtual lab box of buttons beside it

The picture shows the lab bench. The Virtual lab box is beside it.

1

Open mrsajdak.com/spectra on your device.

2

Write your name, the date and your period on the worksheet.

3

Find the Look closer buttons. They zoom in, all the way to one atom.

WorksheetLook closerQuestions
Part 1. Light it upBench1 to 5
Part 2. Inside the tubeInside the tube6 to 8
Part 3. One hydrogen atomOne atom9 to 12
Part 4. Mystery tubesBench13
Part 5 and Wrap it upBench14 to 16

Screenshot: mrsajdak.com/spectra

A plasma globe: a glass ball with pink and purple streamers of glowing gas reaching from the center to the glass

BENCH · QUESTIONS 1 TO 5

Part 1. Light it up

A gas tube is a sealed glass tube with a little gas inside.

You will send electricity through four gases. Then you will look at each glow through spectroscope glasses.

Photo: Supportstorm, public domain

PART 1 · QUESTIONS 1 AND 2

Light a tube. Put on the glasses.

1

Click the H tube on the rack. Or press H under Load a tube.

2

Flip the switch on the power supply. Or press Turn power on.

3

Look at the glow. Write its color for Question 1.

4

Press Put on spectroscope glasses.

5

Watch the glow change. Write what happened for Question 2.

The Virtual lab box: buttons for Turn power off and Put on spectroscope glasses, four Look closer buttons, a grid of eleven gas tubes to load, and a Mystery tube button
The lab bench with a glowing purple gas tube standing in the power supply and a rack of spare tubes beside it

The tube in this picture is argon, not hydrogen.

The power supply holds one tube at a time.

Screenshots: mrsajdak.com/spectra, Bench view

PART 1 · QUESTION 3

Draw the bright lines

1

Load the tube. Turn the power on. Put on the glasses.

2

Find the box under the picture. It is called What a spectroscope would show.

3

Many lines have a number. That is the wavelength in nm.

4

Find that number on your worksheet scale. Draw the line there. Color it in.

5

Do hydrogen, helium, neon and mercury.

The What a spectroscope would show box: a black strip with bright colored lines, each marked with its wavelength, above a rainbow scale from 400 to 700 nanometers
The bench seen through spectroscope glasses: the room is dark and copies of the glowing tube in blue, green, yellow and red stand beside it

Example

This tube is krypton. One line is marked 557.

Draw it a little past halfway from 500 to 600. Color it green.

Krypton is not on your worksheet.

Screenshots: mrsajdak.com/spectra, krypton through the glasses

PART 1 · QUESTIONS 4 AND 5

Glow, lines, and which tells you more

QUESTION 4

Glow

Color of the glow

Take the glasses off. Write the color of the whole tube.

The box at the top right names the color too.

QUESTION 4

Lines

How many? Which is brightest?

Put the glasses on. Count the lines in the Visible light box.

Lots of lines? Write “about” and your best count.

QUESTION 5

Why?

Color or lines?

Two tubes can glow almost the same color.

Scroll down to the Fingerprints chart. Compare the rows. Are any two the same?

A bright bolt of lightning crossing a deep blue storm cloud at night and striking the ground

INSIDE THE TUBE · QUESTIONS 6 TO 8

Part 2. Inside the tube

Lightning is electricity racing through a gas. The gas is air.

A gas tube works the same way. Zoom in. Watch what the electricity does to the atoms.

Photo: Mitchel Coombs, NOAA Weather in Focus

PART 2 · QUESTION 6

Zoom in on the glowing tube

1

Load any tube. Turn the power on.

2

Click the glowing tube. Or press Inside the tube.

3

Watch the small blue dots. Which way do they go?

4

Read the words beside the tube in the picture.

5

Answer Question 6. What are the dots? Where do they come from?

A close view inside a glowing purple gas tube: small circles for atoms, tiny blue dots, and wavy colored arrows flying out through the glass
The four Look closer buttons: Bench, Inside the tube, Single atoms and One atom

The circles are atoms. The wavy arrows are photons.

A dashed arrow is light you cannot see.

Press Esc to step back out.

Screenshots: mrsajdak.com/spectra, Inside the tube

PART 2 · QUESTIONS 7 AND 8

Freeze it and look closely

1

Press Single atoms to zoom in more.

2

Press Freeze. Everything stops.

3

Find an atom with a wavy arrow leaving it. That arrow is a photon.

4

Press Unfreeze. Watch one atom from start to finish.

5

Answer Question 7. What happened to the atom just before the photon left?

Five atoms drawn as rings around a red center, frozen in place, with a wavy blue arrow leaving one atom

The Freeze button is in the top corner of the picture.

It says Unfreeze while the lab is stopped.

These atoms are argon.

QUESTION 8

The lab says “Not to scale.” Think about the size of real atoms and the space between them. Name one difference.

Screenshot: mrsajdak.com/spectra, Single atoms

A black and white portrait of Niels Bohr as a young man in a suit and tie

ONE ATOM · QUESTIONS 9 TO 12

Part 3. One hydrogen atom

In 1913, Niels Bohr pictured the hydrogen atom as rings. Each ring is an energy level.

You will drop one electron from ring to ring. Each drop gives off one photon.

Photo: AB Lagrelius & Westphal, about 1922, public domain

PART 3 · QUESTION 9

Make the electron drop

1

Load H. Press One atom.

2

Uncheck Electron falls back down on its own. Now the readings stay put.

3

Press 3 to 2. The electron goes up, then drops.

4

Read the box at the top right. Copy the color, the wavelength and the energy.

5

Do 4 to 2, 5 to 2 and 6 to 2.

6

Last row: press 1 under Move the electron to level.

One hydrogen atom drawn as six rings. An arrow shows the electron dropping from ring 5 to ring 3, and a dashed wavy arrow marked infrared flies away The box at the top right of the lab. It reads n = 5 to n = 3, light given off 1,282 nm, infrared, energy released 0.97 eV
The Move the electron to level box: level buttons 1 to 6, Zap with electricity, Reset to level 1, four drop buttons from 3 to 2 up to 6 to 2, and a checkbox for Electron falls back down on its own

The pictures show a drop from 5 to 3. It is not in your table.

Leave Show wavelengths and colors checked.

Screenshots: mrsajdak.com/spectra, One atom

PART 3 · QUESTIONS 10 TO 12

Find the pattern

QUESTION 10

Multiply

Wavelength × energy

Do it for every row. Write it in the last column.

Read down the column. What do you notice?

QUESTION 11

Most

The biggest drop

Find the largest energy in your table. Which drop is it?

Could you see its light? Check the color you wrote.

QUESTION 12

Pattern

A bigger drop makes...

Compare a small drop with a big drop.

Does the energy go up or down? Does the wavelength get longer or shorter?

Example

500 × 2.00 = 1,000

A drop that gave 500 nm light and 2.00 eV. These are not your numbers. Use your own.

Two high school students at a lab table building spectroscopes from cardboard tubes, with a printed spectrum chart on the table

MYSTERY TUBE · QUESTION 13

Part 4. Mystery tubes

These students are building a spectroscope. It splits light into its colors.

You will get a gas with no label. Use its lines to work out what it is.

Photo: Gemini Observatory/NOIRLab/NSF/AURA/R. Sparks, CC BY 4.0

PART 4 · MYSTERY TUBE

Guess before you reveal

1

Press Mystery tube. Make sure the power is on.

2

Look at the glow. Then put on the glasses.

3

Write the lines you see. Give their colors and where they are.

4

Scroll down to the Fingerprints chart. Find the row that matches.

5

Write your guess. Then press Reveal.

6

Press Mystery tube again for Trial 2.

A mystery tube seen through spectroscope glasses: the tube glows blue, with a group of blue lines and a few green lines beside it
The Mystery tube button and the gold Reveal button

Reveal shows up only when a mystery tube is loaded.

You get a new gas each time. Your tube will not match this one.

One atom is turned off for a mystery tube.

Two rows of the Fingerprints chart, krypton and xenon, each a black strip with thin colored lines

Two rows of the Fingerprints chart. Which one matches the tube above?

Screenshots: mrsajdak.com/spectra, Mystery tube

PART 4 · QUESTION 13

Claim, evidence, reasoning

Claim

Pick one of your mystery tubes. Name the gas. “It was ____.”

Evidence

Name the lines that proved it. Give their colors. Say where they sit on the scale.

Reasoning

Say why those lines can only mean that gas. Think about what the Fingerprints chart shows for every element.

The What a spectroscope would show box for a mystery tube, with a group of blue lines and a few green lines marked with their wavelengths

Example evidence

“I saw one bright orange line near 610 nm and three blue lines near 450 nm.”

These are not your lines. Use your own.

Screenshot: mrsajdak.com/spectra, Mystery tube

Green northern lights glowing in the night sky behind the dark shapes of spruce trees

BENCH · QUESTIONS 14 AND 15

Part 5. More electrons, more colors

Hydrogen has one electron. Most atoms have many more.

Air is mostly nitrogen. Nitrogen gas is a molecule: two atoms joined together. It gives off light too.

Photo: NPS / Tim Rains

PART 5 · QUESTIONS 14 AND 15

Neon, then nitrogen

QUESTION 14

Count neon’s arrows

Load Ne. Turn the power on. Find the Energy levels box.

Each arrow is one drop. About how many are there?

Hydrogen has 1 electron. Neon has 10. What does that do to the levels?

QUESTION 15

An atom or a molecule?

Load N2. Put on the glasses. Look at the shape of each line.

Now load helium. Compare.

Go back to N2. Press Single atoms. Read the words at the top of the picture.

The Energy levels box for hydrogen: six flat lines from n = 1 at the bottom to n = 6 near the top, each marked with its energy

This is the Energy levels box for hydrogen with the power off. Neon’s looks very different.

Screenshot: mrsajdak.com/spectra, Energy levels

WRAP IT UP · QUESTION 16

How do we know what stars are made of?

The puzzle

No one has ever visited a star. But scientists know stars are mostly hydrogen and helium.

From Part 1

What did each gas show through the glasses? Did any two gases show the same thing?

From Part 4

How did you name a gas you could not see?

Your answer

Put it together. What can a scientist do with the light from a star?

The light of the Sun spread out into rows of color from red at the top to violet at the bottom, crossed by many thin dark lines

Sunlight, spread out into its colors by a spectroscope. Look at all the lines.

Photo: N.A. Sharp/KPNO/NOIRLab/NSO/NSF/AURA, CC BY 4.0

A cluster of bright young stars inside glowing red and blue clouds of gas, photographed by the Hubble Space Telescope

LAST CHECK

Before you hand it in

Name, date and period are on top.

Question 3 has four strips drawn and colored.

All three tables are full.

Question 13 has a claim, evidence and reasoning.

Photo: NASA, ESA, Hubble Heritage Team (STScI/AURA)