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Name that element! Our popular mystery series returns.

This element is a friend of lifeguards and bridges, but an enemy of bad breath. It powers portable gadgets, but weakens a cold. What is it? Follow these eight clues to find out. Then turn the page and test your chemistry IQ.

CLUE 1

OH, SO POPULAR! In its pure form, the mystery element is a pale, bluish-gray metal--the fourth most commonly used metal in the world. But it's only the 23rd most abundant element in Earth's crust, or outermost layer. In nature, this transition metal chemically combines with one or more elements to form compounds. To mine the metal, industries extract it from its ores (mineral-bearing rocks). It is also found in plants, animals, and humans, where it's an essential mineral for growth and development.

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

CLUE 2

RUB IT IN Why do some lifeguards sport a white streak on their nose? They smear on a sunblock containing a compound of oxygen and the mystery element. This compound's particles reflect the sun's invisible ultraviolet (UV) rays away from the skin. "It's like a bunch of tiny mirrors," says Dr. Robert W. Waiters, a dermatologist at Duke University Medical Center in North Carolina. The compound protects against the entire range of both types of UV light--UVA and UVB--that damage skin. Newer versions of this sunblock appear invisible, giving the same protection minus the white nose.

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

CLUE 3

BAD-BREATH BUSTER As a mouthwash ingredient, a compound of this element and chlorine fights bad breath. Anaerobic bacteria, or microbes that don't require oxygen to grow, live in your mouth. These bacteria latch onto proteins (strings of chemicals called amino acids) from food and saliva. As the microbes break down these proteins, they produce sulfur compounds--foul-smelling gases responsible for bad breath. But the mystery element blocks this process by binding to the bacteria so they can't bind to proteins.

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

CLUE 4

PLAY IT AGAIN To make the shiny alloy (mixed metal) brass, just add the mystery element to molten copper, which is in the same period, or row, on the periodic table. "It is like adding sugar to water. You stir it in, and the [mystery element] dissolves," says Frank Goodwin, a metallurgist at an organization that researches the mystery element and other metals. Discarded brass items usually are recycled. Goodwin says that a brass item you own today may have been recycled from a brass bed frame, that was recycled from a ship's brass propeller, and so on through many centuries.

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

CLUE 5

GLOW IN THE DARK Many glow-in-the-dark toys are powered by a phosphorescent compound of the mystery element and sulfur. This compound's electrons (negatively charged particles) absorb energy when light hits them. When the lights go out, the electrons release this absorbed energy as visible light. When all the electrons have returned to their normal energy level, the glowing ceases. Some public buildings install phosphorescent exit signs to point the way out during a power failure.

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

CLUE 6

UNPLUGGED The mystery element lets you listen to your tunes on the go. That's because the batteries in your MP3 player and other portable devices have a negative terminal called an anode, which is made of this element. The battery's cathode, or positive terminal, which is made of a different metal, attracts electrons more strongly than the mystery element does. The cathode pulls electrons from the anode, creating an electric current that powers the device.

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

CLUE 7

COLD STOPPER Studies show that lozenges containing this element reduce common cold symptoms. A cold virus can't replicate, or multiply, on its own. So the virus invades healthy cells lining the airway and forces them to make copies of the virus. Researchers think that one way the mystery element reduces cold symptoms is by binding to proteins on the virus's surface. This interferes with the virus's ability to invade cells, so the virus can't multiply.

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GUESS THE ELEMENT? SCORE 5 POINTS. IF NOT, TRY YOUR LAST CLUE.

CLUE 8

UNSELFISH HERO Engineers use steel to build bridges and to make the cars that cross them. But when steel reacts with water, the metal rusts. To prevent this, steel is galvanized, or dipped in a bath of the molten mystery element, which has 30 protons. This coating keeps water out. Even if the coating gets scratched, the exposed steel won't rust. Instead, the nearby coating slowly dissolves while the steel remains intact. "[The mystery element] actually sacrifices itself to protect steel," Goodwin says.

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GAME'S OVER. NOW TURN TO PAGE 14.

Anatomy of an Element

X Atomic number

?? Element symbol

Name Element name

X.XXXX Average atomic mass

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

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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.

PHYSICAL: Chemistry

Name That Element!

POST-READING DISCUSSION:

* In 1860, the French government mandated that all rooftops in Paris be covered with zinc sheeting. Why do you think the government chose this material for the city's rooftops? (Answer: Zinc doesn't rust, so it makes a long-lasting and weatherproof material for rooftops.)

DID YOU KNOW?

* The zinc compound used in sunblock is also found in calamine lotion. Many people dab this pink concoction onto mosquito bites to relieve itching

* The manufacture of galvanized steel--the material used to build car bodies, guardrails, light poles, and bridges--uses nearly 50 percent of the zinc produced each year.

* All plants need zinc to grow, but too much can kill them. That's unless the plant is a zinc pansy. This flower loves to grow where other plants can't--on piles of zinc-rich dirt removed from mines.

* Zinc can be recycled indefinitely; it never loses its physical or chemical properties in the process.

CRITICAL THINKING:

* Pennies were originally made entirely of the metal copper. But in 1982, the United States Mint began making zinc pennies with a thin copper coating. Why do you think the Mint made the switch? (Answer: Zinc is less expensive and more abundant than copper. That makes zinc pennies cheaper to produce than the ones made entirely of copper. Because zinc is a bluish-gray metal, the Mint coats the zinc pennies in copper.)

CROSS-CURRICULAR CONNECTIONS:

SOCIAL STUDIES: China, Australia, and Peru are the world's largest suppliers of zinc. Have each student choose a different metal from the periodic table and do research to find out where on Earth it is most abundant. Then as a class, mark where the different elements are found on a world map.

RESOURCES

* Learn more about zinc by visiting: www.zinc.org/

* Foods like oysters, meat, and poultry are high in zinc. Visit this Web site from the National Institutes of Health to learn why this mineral should be an important part of your diet: http://dietary-supplements.info.nih.gov /factsheets/cc/zinc.html

* Do you think you know which of the periodic table's chemical symbols go with which element? Test your knowledge by playing the "Find the Element" game at: www.chemsoc.org/networks/learnnet/ptdata /games/findelement.htm

DIRECTIONS: Rewrite the false statements below to make them true.

1. In its pure form, zinc is a noble gas. It's the 23rd most abundant element in Earth's atmosphere.

2. Sunblock containing a compound of calcium and zinc helps reflect the sun's X-rays away from the skin. The compound protects against both types of X-rays--infrared and ultraviolet light--that damage skin.

3. Anaerobic bacteria are bugs that grow in air and water.

4. Zinc and nickel combine to make the amalgam brass. These two elements belong to the same group.

5. A cold virus replicates easily. Once the virus enters a person's airway, it makes multiple copies of itself.

Answer

1. In its pure form, zinc is a pale, bluish-gray metal. It's the 23rd most abundant element in Earth's crust

2. Sunblock containing a compound of oxygen and zinc help reflect the sun's ultraviolet (UV) radiation away from the skin The compound protects against the entire range of both types of UV light--UVA and UVB--that damage skin.

3. Anaerobic bacteria are microbes that don't require oxygen to grow.

4. Zinc and molten copper combine to make the alloy brass These two elements belong to the same period.

5. A cold virus can't replicate on its own So the virus invades healthy cells lining a person's airway and forces them to make copies of the virus
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Article Details
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Title Annotation:PHYSICAL CHEMISTRY
Author:Adams, Jacqueline
Publication:Science World
Geographic Code:1USA
Date:Mar 10, 2008
Words:1632
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