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12 Cards in this Set
- Front
- Back
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About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? |
carbon, hydrogen, nitrogen, oxygen |
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Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants? |
Iodine |
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Why is each element unique and different from other elements in chemical properties? |
Each element has a unique # of protons in the nucleus |
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What are isomers, polymers, and isotopes? What does inert mean? |
Isomers= two+ compounds with the same formula but different arrangement of atoms in the molecule and different properties. Polymers= monomers linked by chemical bonds through polymerization Isotopes= same # of protons (same atomic #) but different # of neutrons (different atomic mass) Inert= unreactive to other elements naturally |
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Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that... |
an electron moves to electron shell farther away from the nucleus |
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The atomic number of neon is 10. Therefore, which of the following is most correct about an atom of neon? |
has 8 electrons in outer electron shell and is inert |
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From its atomic number of 15, it is possible to predict that the phosphorus atom has |
15 protons and 15 electrons (atoms usually have the same # of protons and electrons) |
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Atoms whose outer electron shells contain 8 electrons tend to |
be both chemically inert and gaseous at room temperature |
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Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true? |
Molybdenum atoms can have between 50 and 58 neutrons |
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Carbon-12 is the most common isotope of carbon, and has an atomic mass of 12 daltons. A mole of carbon in naturally occurring coal, however, weighs slightly more than 12 grams. Why? |
Some carbon atoms in nature have more neutrons (isotopes always have different # of neutrons) |
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Which of the following best describes the relationship between the atoms described below? Atom 1 Atom 2 1 3 1H 1H |
They are isotopes |
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The organic molecules in living organisms have a measurably lower ratio of carbon-13/carbon-12, two stable isotopes of carbon that comprise approximately 1.1% and 98.9% of atmospheric carbon, respectively. What is a reasonable explanation for this phenomenon? |
Photosynthesis preferentially uses carbon dioxide molecules with carbon-12, and the lower carbon-13/carbon-12 ratio propagates through the food chain. |
