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STANDARDS

NGSS: Core Idea: PS1.A

CCSS: Literacy in Science: 7

TEKS: 6.6A, 7.6A, 8.5A, 8.5B, C.5A, C.5B

Name That Element!

Which element on the periodic table fights dandruff, directs drivers, and makes copies of your homework? Follow these five clues to find out. Then turn the page to show what you know about chemistry.

WORLD HISTORY ARCHIVE/ALAMY STOCK PHOTO

EUREKA!

EUREKA!

When Swedish scientist Jöns Jacob Berzelius first encountered the mystery element in 1817, he thought it was the known element tellurium (Te). He later realized that he’d made a new discovery. Small amounts of this element are found throughout Earth’s crust, or outer layer. Even though the mystery element is a nonmetal, it’s often located in ores. These rocks contain valuable metals like silver (Ag) and copper (Cu)—which is a member of the same period, or row, as the mystery element. Got the answer? Score 100 points. Not sure? Move on to the next clue.

Swedish scientist Jöns Jacob Berzelius first came across the mystery element in 1817. He thought it was the known element tellurium (Te). Later, he realized that he’d made a new find. Small amounts of this element are found throughout Earth’s crust, or outer layer. The mystery element is a nonmetal, but it often occurs in ores. These rocks contain valuable metals like silver (Ag) and copper (Cu). And copper is in the same period, or row, as the mystery element. Got the answer? Score 100 points. Not sure? Move on to the next clue.

YANOKON/SHUTTERSTOCK.COM

GO NUTS!

GO NUTS!

“[The mystery element] is essential for life,” says Richard Glass, a retired chemist who worked at the University of Arizona. One reason is that it protects cells—the smallest units of life—from damage that could lead to diseases like cancer. Most Americans get sufficient amounts of this element through their daily diets. However, eating large amounts of the element could be toxic. Brazil nuts are so high in this element that some doctors suggest eating them only once in a while. Figured it out? Score 80 points. Otherwise, read clue #3.

“[The mystery element] is essential for life,” says Richard Glass. He’s a retired chemist from the University of Arizona. One reason is that it protects cells, the smallest units of life. It prevents cell damage that could lead to diseases like cancer. Most Americans get enough of this element from their daily food. But eating large amounts of the element could be toxic. Brazil nuts are very high in this element. That’s why some doctors suggest eating them only once in a while. Figured it out? Score 80 points. Otherwise, read clue #3.

VALERY VOENNYY/ ALAMY STOCK PHOTO

COPY THAT

COPY THAT

Push the start button on a photocopier and a bright light moves across the document you want copied. The light reflects down to a rolling surface inside the machine, called a drum, which is coated with the mystery element. Because the element is photosensitive, or sensitive to light, it creates an electrically charged shadow of the document’s image on the drum. Black toner powder sticks to the shadow. Then as the drum turns, the toner is inked onto a blank piece of paper, creating your copy. Score 60 points if you know the element. Still trying? Then read on.

Want to copy a document? Push the start button on a photocopier, and a bright light moves across the document. The light reflects down to a rolling surface inside the machine. It’s called a drum, and it’s coated with the mystery element. This element is photosensitive, or sensitive to light. So it creates an electrically charged shadow of the document’s image on the drum. Black toner powder sticks to the shadow. The drum turns, and the toner is inked onto a blank piece of paper. It creates your copy. Score 60 points if you know the element. Still trying? Then read on.

ALENA TS/SHUTTERSTOCK.COM

DANDRUFF FIGHTER

DANDRUFF FIGHTER

As new skin cells grow, old ones fall off. Skin cells on the scalp normally turn over every 21 days. But for a person with dandruff, a condition caused by irritation to the scalp, the cells regenerate twice as fast. This causes the old cells to build up in clumps before coming off. A compound containing the mystery element and sulfur (S), found in the same group, or column, helps slow cell growth. That’s why it’s used as an ingredient in antidandruff shampoos. Know the element? Score 40 points. If not, you’re in luck. There’s one more clue.

As new skin cells grow, old ones fall off. Skin cells on the scalp normally turn over every 21 days. But irritation to the scalp can cause a condition called dandruff. Then new cells grow twice as fast. This causes the old cells to build up in clumps before they come off. A compound of the mystery element and sulfur (S) helps slow cell growth. So it’s used as an ingredient in antidandruff shampoos. These two elements are in the same group, or column. Know the element? Score 40 points. If not, you’re in luck. There’s one more clue.

ISTOCKPHOTO/GETTY IMAGES

TRAFFIC STOP

TRAFFIC STOP

The mystery element helps prevent road accidents by telling drivers when they need to stop. To make the glass coverings for the lights on traffic signals, manufacturers mix ingredients together: sand, ash, and limestone. “If you want red-colored glass, you toss in some [of the mystery element],” says Glass. The mixture is melted at temperatures greater than 1,425°C (2,597°F). Then the molten material is shaped into a round, red disc and allowed to cool. This traffic stopping element has 34 protons. Write your answer and score 20 points. Then turn the page.

The mystery element helps prevent road accidents. That’s because it tells drivers when to stop. The lights on traffic signals have glass coverings. To make the glass, manufacturers mix sand, ash, and limestone. “If you want red-colored glass, you toss in some [of the mystery element],” says Glass. The mixture is melted at temperatures above 1,425°C (2,597°F). Then it’s shaped into a round, red disc and allowed to cool. This traffic stopping element has 34 protons. Write your answer and score 20 points. Then go on.

PERIODIC TABLE

The periodic table is a systematic way to organize Earth’s elements—substances that each consist of only one kind of atom. Today, there are 118 known chemical elements.

Elements on the periodic table are arranged by their atomic numbers in ascending order. Hydrogen (H), for example, has an atomic number of 1 and is the lightest known natural element.

Scientists have created elements with atomic numbers greater than 92, but they don’t exist naturally.

The periodic table is a systematic way to organize Earth’s elements—substances that each consist of only one kind of atom. Today, there are 118 known chemical elements.

Elements on the periodic table are arranged by their atomic numbers in ascending order. Hydrogen (H), for example, has an atomic number of 1 and is the lightest known natural element.

Scientists have created elements with atomic numbers greater than 92, but they don’t exist naturally.

ANATOMY OF AN ELEMENT

ATOMIC NUMBER equals the number of protons (positively charged particles) in an atom’s nucleus, or center. Each element consists of atoms that all have the same number of protons, and so each 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 is the average mass of the naturally occurring isotopes of an element. Isotopes are atoms of an element with the same number of protons but with different numbers of neutrons.

ATOMIC NUMBER equals the number of protons (positively charged particles) in an atom’s nucleus, or center. Each element consists of atoms that all have the same number of protons, and so each 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 is the average mass of the naturally occurring isotopes of an element. Isotopes are atoms of an element with the same number of protons but with different numbers of neutrons.

ATOMIC STRUCTURE

The mystery element gets its name from the Greek word selene, which means moon.

The mystery element gets its name from the Greek word selene, which means moon.

SHOW WHAT YOU KNOW

Use the periodic table below and what you learned about the mystery element on the previous pages to answer the following questions.


1. Which of these elements is a nonmetal?

A. astatine (At)

B. barium (Ba)

C. samarium (Sm)

D. vanadium (V)


2. Platinum (Pt) belongs to group _____.

A.

B. 6

C. 10

D. 18


3. The atomic mass of indium (In) is _____.

A. 13 

B. 30

C. 49

D. 114.8


4. Which of the following elements does NOT belong to the same period as the others?

A. cobalt (Co)

B. germanium (Ge)

C. krypton (Kr)

D. tellurium (Te)


5. Which of the following is a gas?

A. bromine (Br)

B. cesium (Cs)

C. plutonium (Pu)

D. argon (Ar)

SHOW WHAT YOU KNOW

Use the periodic table below and what you learned about the mystery element on the previous pages to answer the following questions.


1. Which of these elements is a nonmetal?

A. astatine (At)

B. barium (Ba)

C. samarium (Sm)

D. vanadium (V)


2. Platinum (Pt) belongs to group _____.

A. 1 

B. 6

C. 10

D. 18


3. The atomic mass of indium (In) is _____.

A. 13 

B. 30

C. 49

D. 114.8


4. Which of the following elements does NOT belong to the same period as the others?

A. cobalt (Co)

B. germanium (Ge)

C. krypton (Kr)

D. tellurium (Te)


5. Which of the following is a gas?

A. bromine (Br)

B. cesium (Cs)

C. plutonium (Pu)

D. argon (Ar)

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