Name that element!

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Which element on the periodic table gives maraschino cherries their vivid red color, keeps car headlights shining bright, and is a powerful germ killer? Follow these eight clues to find out. Then turn the page to test your chemistry I!].

CLUE 1

DYNAMIC DUO 

The mystery element--a nonmetal--is usually a found paired with its "twin." That's because the smallest unit of this element, or its atom, is highly unstable. So two atoms of the mystery element frequently bond together to form a more stable diatomic molecule (particle containing two atoms). At room temperature, the mystery element sublimes, changing from a shiny black solid into purple gas.

GOT IT ALREADY? SCORE 100 POINTS. IF NOT, READ CLUE #2.

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CLUE 2

CHERRY RED

Some of the cherries that top sundaes owe their tempting color to the mystery element. When the element combines with oxygen (O), carbon (C), and sodium (Na), it forms a red food dye. Most maraschino cherries wouldn't be bright red without the mystery element, says Penny Martin, a food chemist at Sensient Colors. The red dye also colors some candies, which in turn can stain your tongue red.

NABBED THE ANSWER? SCORE 80 POINTS. STILL GUESSING? 60 TO THE NEXT CLUE.

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CLUE 3

SAY "CHEESE!"

It helps capture your grin on film. Black-and-white camera film is coated with a light-sensitive compound (two or more elements that are chemically combined) of the mystery element and silver (Ag). Both elements are members of the same period (row) on the periodic table. When you snap a photo, light enters the camera lens. The compound reacts with the light to create the shades of dark and light that make up a picture-perfect image.

GAME OVER ALREADY? SCORE 60 POINTS. STILL PLAYING? CHECK OUT CLUE #4.

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CLUE 4

COLOR CHANGE

Fries may not taste sweet, but a simple test using the mystery element shows that this snack is packed with long chains of sugars, called starch. This sugary substance is found in some plants. So foods made from plants like potatoes have large amounts of starch. To find which foods contain this sugar, you can add a few drops of Lugol's solution (the mystery element dissolved in water) to the snack. When the brown-colored solution comes into contact with starch, the mystery element reacts and turns the solution blue.

NAME IT NOW? SCORE 40 POINTS. OTHERWISE, READ ON.

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CLUE 5

SALTY FIX

In 1924, salt companies began adding a compound that contains the mystery element to table salt. Why? Many people weren't getting enough of the element in their diets. Without sufficient levels of the element, the thyroid (a gland in the throat) can't produce needed hormones, or chemical messengers, that regulate energy use. "It's very easy to prevent this deficiency by adding [the element] to salt," says Robert Baldwin of the Centers for Disease Control and Prevention.

HIT ON THE ANSWER? SCORE 20 POINTS. IF NOT, KEEP TRYING!

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CLUE 6

GOT ZITS!

Cow's milk contains high levels of the mystery element. That may be partly to blame for teenage acne. Farmers add the element to cow feed to help the animals fight infections. As a result, the element ends up in your body when you drink milk or eat cheese. "[The element] can aggravate already existing acne in some people," says Harvey Arbesman, a dermatologist (skin doctor) at the University of Buffalo in New York. For those people, eating fewer dairy products may help in reducing the number of new breakouts, he says.

SCORE 10 POINTS IF YOU NAME THE ELEMENT WITH THE HELP OF SIX CLUES. STILL GUESSING? READ ON.

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CLUE 7

HIGH BEAMS

It helps keep some headlights burning bright. The lightbulbs in "halogen" headlights are filled with a gas of either the mystery element or bromine (Br), an element in the same group (column) on the periodic table. The gas pushes on the bulb's glowing, tungsten (W) filament wire. In an ordinary bulb, tungsten gradually evaporates, so the wire thins and the bulb burns out. The force from the mystery element keeps the tungsten in halogen bulbs from evaporating as quickly. Result: a longer-lasting bulb.

GUESS THE ELEMENTS? SCORES 5 POINTS. IF NOT, TRY YOUR LAST CLUE.

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CLUE 8

A cut is an open invitation for germs to get inside your body and cause an infection. When the mystery element combines with sodium (Na) and is added to rubbing alcohol, it creates a strong antiseptic, or germ killer. Just a dab on a cut can rid it of harmful germs. Hint: This element has 53 protons (positively charged particles) in its nucleus, or center.

GAME'S OVER. NOW TURN TO PAGE 14.

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Anatomy of an Element</p> <pre> X Atomic number ?? Element symbol Name Element name x.XXXX  Average atomic masses </pre> <p>KEY DEFINITIONS:

ATOMIC NUMBER equals the number of protons (positively charged particles) in an atom's nucleus, or center. Every element contains a different number of protons, and so has a unique atomic number. In a neutral atom, the number of protons and the number of electrons (negatively charged particles) are equal.

ATOMIC MASS equals the number of protons plus the number of neutrons (uncharged particles) found in a single atom of an element. The atom's mass is in its nucleus, which houses both protons and neutrons.

The Periodic Table

The periodic table is a systematic way to organize Earth's elements, substances that consist of atoms of only one kind. Today, there are 112 known and named chemical elements. Elements are arranged according to their increasing atomic numbers. Hydrogen (H), for example, has an atomic number of 1 and is the lightest known natural element on Earth. Scientists have created elements with atomic numbers greater than 92, but they don't exist naturally. Some scientists think they may have created elements heavier than 112, but until an element is confirmed by two different labs, it usually isn't listed on the periodic table.

DID YOU KNOW?

* When iodine and silver combine, they form tiny crystals. Spraying these crystals into clouds helps increase rainfall. How? Water molecules in the clouds attach to the crystals, forming heavy, moisture-rich droplets that fall to the ground as rain or snow. This crystal-spraying process, called cloud seeding, is sometimes used near ski resorts to increase snowfall on the slopes.

CRITICAL THINKING:

* Archaeologists use Lugol's solution to test for starch molecules on tools used by ancient cultures. How might this test help scientists learn about a culture? (Answer: The test helps scientists learn about a culture's diet, such as the plants they ate and where or how the people gathered food.)

CROSS-CURRICULAR CONNECTIONS:

MATH: The Food and Drug Administration recommends that teens consume between 120 and 150 micrograms of iodine each day. Do research to find out what foods are good sources of iodine, along with the amount of the element in each serving of the foods. Then, turn the data into a bat graph.

RESOURCES

* For more facts on iodine, visit: www.webelements.com/webelements/elements/text/l/key.html

* To learn more about the history of iodized salt, visit the Salt Institute's Web site: www.saltinstitute.org/37.html

It's your choice

Test your chemistry IQ! Answer the following questions about elements and the periodic table.

1. Name that element!

2. When two atoms combine to form a particle, it's called a(n)--molecule.

A double

B diatomic

C unstable

D atomic

3. When an element sublimes, it

A changes from a gas to a solid.

B stays in a solid state.

C changes from a solid to a gas.

D forms a liquid at room temperature.

4. Which of the following is a nonmetal?

A Manganese (Mn)

B Silicon (Si)

C Potassium (K)

D Lithium (Li)

5. Which of the following elements is not found in the same group as the others?

A Zinc (Zn)

B Mercury (Hg)

C Cadmium (Cd)

D Nickel (Ni)

6. How many electrons are there in an atom of Tin (Sn)?

A 25

B 34

C 50

D 10

ATOM FACT: Each atom of the mystery element has 53 electrons orbiting a nucleus that contains 53 protons and 74 neutrons.

1. Iodine

2. b

3. c

4. b

5. d

6. c

DIRECTIONS: On a separate piece of paper, defend or dispute the following statements. (Hint: Defend means to explain why a statement is correct. Dispute means to explain why a statement is incorrect.)

1. French fries do not contain starch.

2. You can find iodine in table salt.

3. Drinking cow's milk may be partly to blame for acne.

4. Halogen lightbulbs burn out faster than ordinary lightbulbs.

1. Dispute: French fries are packed with long chains of sugars called starch. This sugary substance is found in some plants. So foods made from plants like potatoes have large amounts of starch To find which foods contain this sugar, add a few drops of Lugol's solution, which is iodine dissolved in water, to the food item. When the brown colored solution comes in contact with starch, the mystery element reacts and turns the solution blue.

2. Defend: In 1924, salt companies began adding a compound that contains iodine to table salt. Many people weren't getting enough of the element in their diets. Without sufficient levels of the element, the thyroid gland can't produce hormones that regulate energy use. To prevent this deficiency, some companies began adding iodine to salt.

3. Defend: Cow's milk may be partly to blame for acne. That's because it contains high levels of iodine. Farmers add iodine to cow feed to help the animals fight infections So when a person drinks milk or eats cheese, the element ends up in the human body. Dermatologists believe that iodine can aggravate already existing acne in some people For those people, eating fewer dairy products may help reduce the number of new breakouts

4. Dispute: Halogen lightbulbs last longer than ordinary lightbulbs In all lightbulbs, the tungsten that makes up the glowing filament wire gradually evaporates, so the wire thins and the bulb burns out Halogen lightbulbs are filled with a gas of either iodine or bromine The force of the gas keeps the tungsten in a halogen bulb from evaporating as quickly. Result: a longer lasting bulb.