Name that element! It’s the world’s most powerful element, fueling both nuclear weapons and power plants. Our mystery element is softer than steel, denser than lead, and has existed for more than 6.6 billion years—longer than Earth itself. Can you name it? For help, grab a periodic table and follow these eight clues. Then turn the page to test your “element IQ.”
Nicole Dyer
CLUE 1 A ROCK START
The element’s silver-white metal is found nearly everywhere–soil, plants, water. But it’s most abundant in rocks, where it combines with other elements to form crystals of naturally occurring chemicals called minerals, or ores. Its most common ore: a marblelike rock called pitchblende.
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CLUE 2 IN THE MIX
In nature it exists as a mixture of three different forms or isotopes. An atom of each isotope shares an equal number of positively charged protons, but a different number of neutrons (uncharged atomic particles). The isotope pictured at right was extracted from an ore and forged into a solid ball. A single atom has 143 neutrons.
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CLUE 3 GET A (HALF) LIFE
It has a half-life of 4.5 billion years. In other words, “If you looked at a chunk of the element today, 4.5 billion years from now, half of it would be gone,” says chemist Al Sattelberger at the Los Alamos National Laboratory in New Mexico. That’s because it’s a radioactive element–an element with an unstable nucleus that decays over time. The reaction is described as nuclear because it occurs inside an atom’s nucleus.
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CLUE 4 SHOCKING REACTION
It generates more than 16 percent of the world’s electricity. That’s because one of its most powerful isotopes yields massive amounts of heat energy, or radiation, under certain conditions. “A single pound can generate as much energy as 1,500 tons of coal,” says Sattelberger.
Where does the energy come from? Atoms, the microscopic particles that make up everything in the universe, including elements. When the isotope’s nucleus is smashed in two, energy is released. At the same time, it ejects two or three neutrons. They split apart other nearby nuclei, which in turn release more energy. The nuclear process is called a fission chain reaction. Using elaborate machinery, its energy can be harnessed to fuel nuclear power plants.
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CLUE 5 GLOW-IN-THE-DARK GLASSWARE
Over 200 years ago, it was added to glassware to give it a decorative green-yellow gleam. Known as Vaseline glass (it resembles petroleum jelly), it’s the only transparent glass that glows beneath an ultraviolet light, a light source that emits energy waves at a higher frequency than visible light. Vaseline glass is mildly radioactive, a property shared by all of the actinide elements, but the mystery element was banned for use as a coloring agent in the 1940s.
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CLUE 6 HEAVY METAL
It’s the heaviest element found in nature. In its metallic form, it’s 19 times denser than water–a property that makes it useful in yacht keels and as counterweights in airplane rudders. Consider this: Elements are organized on the periodic table according to atomic number and weight, with the lightest element being hydrogen (H).
SCORE 10 POINTS IF YOU NAME THE ELEMENT WITH THE HELP OF SIX CLUES. STILL GUESSING? READ ON.
CLUE 7 DEADLY DEEDS
If a fission chain reaction is uncontrolled–meaning that millions of nuclei are split in less than a fraction of a second with no way to slow them down–it leads to a catastrophic explosion. The explosion creates a towering plume of smoke called a mushroom cloud. The mystery element was used to make the world’s first atomic bomb, dropped on Hiroshima, Japan, during World War II. It killed at least 70,000 people.
GUESS THE ELEMENT. SCORE 5 POINTS. IF NOT. TRY YOUR LAST CLUE.
CLUE 8 OUT OF THIS WORLD
The mystery element was named after the third largest planet in the solar system. The giant gas planet has a distinctive green coloring, much like some of the minerals that contain the mystery element.
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ANATOMY OF AN ELEMENT
X–Atomic number
?–Element symbol–Element name
XXXXXXX–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 hence has a unique atomic number.
ATOMIC MASS equals the number of protons plus the number of neutrons found in a single atom of an element. The weight of an atom resides in its nucleus, which houses both protons and neutrons.
The Periodic Table
[ILLUSTRATION OMITTED]
The periodic table is a systematic way to organize Earth’s elements, which can’t be broken down into simpler substances. Today, there are 112 known and named chemical elements. Elements are arranged according to their increasing atomic number. 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.
IT’S YOUR CHOICE
Test your chemistry IQ! Answer the following questions about elements and the periodic table.
1 Name the mystery element!
2 Which statement is false:
A isotopes of the same element share the same atomic number.
B Isotopes of the same element share the same chemical properties.
C Isotopes of the same element share the same number of neutrons.
D Isotopes are different forms of the same element.
3 Which three elements are arganized as Inner transition metals?
A Neodynium, Tungsten, Chromium
B Thorium, Plutonium, Curium
C Lutetium, Osmium, Mercury
D Neodynium, Europium, Rhemium
4 Horizontal rows in a periodic table are called
A alkali metals
B columns
C periods
D tables
5 Which element has 20 protons inside its nucleus:
A Calcium (Ca)
B Chlorine (Cl)
C Actinium (Ac)
Resources
For more on uranium and its use as a nuclear fuel, visit the Uranium Information Center: www.uic.com.au/uran.htm
For more on uranium and the periodic table, visit Los Alamos National Laboratory’s Chemistry Division online at: periodic.lanl.gov/default.htm
Want to find some entertaining methods to help your students learn the periodic tablet Take a look at two Web sites:
Creative Chemistry is a Web site operated by Nigel Saunders, Head of Chemistry at Harrogate Granby High School in the United Kingdom. It’s filled with worksheets and activities. Students can even play an online periodic table jigsaw puzzle in the “fun stuff” section. www.creative-chemistry.org.uk/index.htm
A Visual Interpretation of the Table of Elements takes students on a Flash or HTML tour through the periodic table. Each of the 109 elements is presented through visual images, description, and interesting trivia. Visit: www.chemsoc.org/viselements/
Did You Know?
* Uranium-238 accounts for 99.27 percent of all uranium naturally existing in the environment.
* The general population is exposed to scant doses of uranium mostly through food and water. About 99 percent is excreted from the body through feces.
* The average daily uranium intake from food ranges from 0.07 to 1.1 micrograms per day. According to the World Health Organization, uranium doses greater than 0.6 micrograms per kilogram of body weight per day are hazardous.
Cross-Curricular Connection
Math: The equation A = [A.sub.o] x [(1/2).sup.t/T] can be used to calculate the half-life of an element.
A = remaining amount of the element in grams
t = time (in days)
[A.sub.o] = initial amount of element
T = element’s half-life
Use the equation to determine how much of an 80-gram sample of iodine remains after 8, 16, 24, and 32 days? Iodine has a half-life of 8 days.
Critical Thinking: What are some risks and benefits of uranium?
Directions: Match the word(s) in the left column with the correct phrase in the right column.
1. elements a. atoms splitting and crashing into each other
2. uranium b. lightest element
3. hydrogen c. things that can’t be broken down into simpler
substances
4. isotopes d. type of heat energy
5. radiation e. heaviest element
6. ores f. minerals
7. radioactive g. different forms of an element
8. fission h. having an unstable nucleus that decays over time
ANSWERS
1. c 2. e 3. b 4. g 5. d 6. f 7. h 8. a
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