Name that element!
ANATOMY OF AN ELEMENT
Atomic Number atomic number, often represented by the symbol Z, the number of protons in the nucleus of an atom, as well as the number of electrons in the neutral atom. Atoms with the same atomic number make up a chemical 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, 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 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.
1 LIKE BUTTER
Like nearly all metals, the mystery element in its pure form is shiny, conducts heat and electricity, and is solid at room temperature. But unlike most metals, it's as soft as butter. This alkali metal quickly whitens as it oxidizes, or reacts with oxygen (O), in air. It reacts violently with water, producing heat and hydrogen (H) gas that bursts into flames. Since it's so explosive, the mystery element must be stored in oil. Got it already? Score 100 points. If not, read clue 2.
2 DIMMER dim·mer
1. A rheostat or other device used to vary the intensity of an electric light.
a. A parking light on a motor vehicle.
b. A low beam. LIGHTS
Cities are filled with lights, from flashing neon (Ne) signs to street lamps. The mystery element helps city stargazers see the night sky a bit better. It's burned in certain outdoor lights because it casts a soft, yellow glow. These lights are preferable to white street lamps, whose brightness makes it hard to see the stars. "The lamps don't cause as much light pollution," says Eric Betterton, an atmospheric and environmental chemist at the University of Arizona (body, education) University of Arizona - The University was founded in 1885 as a Land Grant institution with a three-fold mission of teaching, research and public service. . "It's easier on astronomers' eyes." Figured out the answer? points. Not yet? Go to clue 3.
Many fire extinguishers spray foam loaded with the mystery element combined with carbon (C) and oxygen. This carbonate form of the mystery element is also known as baking soda. At high temperatures, baking soda releases carbon dioxide gas, which is why adding it to dough causes baked goods to rise. When a fire extinguisher's baking-soda-loaded foam hits a fire, the carbon dioxide gas that's created robs the flames of oxygen and smothers them. Game over? Score 60 points. Still playing? Check out clue 4.
4 POWER AID
As an ingredient in most sports drinks, this element helps the body recover after a workout. That's because the mystery element is an electrolyte. When it's dissolved in the body's fluids, it forms ions, or charged particles--most often losing one of its 11 electrons to become positively charged. Electrolytes help your muscle cells and nerve cells function properly. "When you're sweating a lot, sports drinks deliver what plain water can't--they replenish the electrolytes lost in sweat," says Bob Murray of the Gatorade Sports Science Institute in Barrington, Illinois. Score 40 points if you've named the element. No luck? Try the last clue.
5 FLAVOR ENHANCER
Some snacks wouldn't taste the same without a compound containing the mystery element and chlorine (Cl), found in the same period, or row, on the periodic table. Your taste buds have specialized receptors that sense the mystery element. It's one of 25 elements essential to your diet, but too much of it may lead to high blood pressure. The American Heart Association recommends consuming no more than 2,400 milligrams (less than one ounce) of the element each day. Guessed the element? Score 20 points. Otherwise, turn to page 30.
WHAT'S THE ELEMENT
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 112 known and named chemical elements. Elements 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. 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.
IT'S YOUR CHOICE Use your chemistry knowledge and the periodic table above to answer the following questions.
The mystery element is found in abundance in rocks and in the ocean as a molecule commonly known as table salt.
1. Elements in group 17 on the periodic table are known as halogens. Which of the following elements is NOT a halogen?
(A) iridium iridium (ĭrĭd`ēəm), metallic chemical element; symbol Ir; at. no. 77; at. wt. 192.22; m.p. about 2,410°C;; b.p. about 4,130°C;; sp. gr. 22.55 at 20°C;; valence +3 or +4. (Ir)
(B) chlorine (Cl)
(C) iodine (I)
(D) astatine astatine (ăs`tətēn,–tĭn) [Gr.,=unstable], semimetallic radioactive chemical element; symbol At; at. no. 85; at. wt. of most stable isotope 210; m.p. 302°C; (estimated); b.p. (At)
2. Metals that tend to conduct electricity better appear farther to the right in a period. Which of the following has a greater conductivity than nickel (Ni)?
(A) titanium (Ti)
(B) potassium (K)
(C) gallium (Ga)
(D) iron (Fe)
3. If barium (Ba) loses two electrons, it will contain the same number as which element?
(A) hafnium hafnium (hăf`nēəm), metallic chemical element; symbol Hf; at. no. 72; at. wt. 178.49; m.p. about 2,227°C;; b.p. 4,602°C;; sp. gr. 13.31 at 20°C;; valence +4. (Hf)
(B) xenon xenon (zē`nŏn) [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.29; m.p. −111.9°C;; b.p. −107.1°C;; density 5.86 grams per liter at STP; valence usually 0. (Xe)
(C) cesium cesium (sē`zēəm) [Lat.,=bluish gray], a metallic chemical element; symbol Cs; at. no. 55; at. wt. 132.9054; m.p. 28.4°C;; b.p. 669.3°C;; sp. gr. 1.873 at 20°C;; valence +1. (Cs)
(D) calcium (Ca)
4. An ion is defined as--.
(A) a positively charged particle
(B) a negatively charged particle
(C) a particle with no charge
(D) any charged particle
5. A carbonate contains which two elements?
(A) calcium (Ca) and boron boron (bōr`ŏn) [New Gr. from borax], chemical element; symbol B; at. no. 5; at. wt. 10.81; m.p. about 2,300°C;; sublimation point about 2,550°C;; sp. gr. 2.3 at 25°C;; valence +3. (B)
(B) potassium (K) and nitrogen (N)
(C) chlorine (Cl) and sodium (Na)
(D) carbon (C) and oxygen (O)
6. What is the atomic mass of rhodium rhodium (rō`dēəm), metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.9055; m.p. about 1,966°C;; b.p. 3,727±100°C;; sp. gr. 12.41 at 20°C;; valence +2, +3, +4, +5, or +6. (Rh)?
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|Title Annotation:||CHEMISTRY: PERIODIC TABLE|
|Date:||Apr 13, 2012|
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