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24 Cards in this Set
- Front
- Back
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What four elements make up most of all living organisms?
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carbon, hydrogen, oxygen, and nitrogen (“CHON”)
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What element is commonly added to table salt to prevent goiter?
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iodine (I)
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An atom has a mass number of 13 and an atomic number of 6. (a) How many protons does the atom have? (b) How many neutrons does the atom have? (c) How many electrons does it have?
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(a) 6 (b) 7 (c) 6
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If a phosphorous atom has 15 protons, 15 electrons, and 16 neutrons what is its mass number?
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mass number = number of protons + number of neutrons = 15 + 16 = 31
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Examine the periodic table of the elements in these course pack notes. How many protons does silver (Ag) have?
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47
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If you wanted 1 mole of magnesium chloride (MgCl2), how much MgCl2 would you weigh out?
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95.3 g
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What is the atomic number of an atom?
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The atomic number of an atom is the number of protons in its nucleus.
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A student described the Bohr model of an atom as 14p 2,8,4. What can you say about this atom?
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The atom is silicon (Si) and has an atomic number of 14 (in other words, 14 protons). There are 2 electrons in its first principle energy level (full), 8 electrons in its second principle energy level (full), and 4 electrons in its outermost energy level (or “valence shell”).
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The further an electron is away from the nucleus, the greater its energy? Is this statement true or false?
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true
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Examine the periodic table of the elements in these course pack notes. (a) How many electrons are present in a chloride anion (Cl-1)? (b) How many electrons are present in the outermost energy level of a chloride anion (Cl-1)?
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(a) 18 (b) 8
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What does the Aufbau principle tell us?
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The Aufbau principle tells us that electrons fill the lowest energy orbital first, followed by the orbital with the next highest energy level, and so on.
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Why are pure elements not very common in nature?
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Pure elements are not very common in nature because most elements are quite reactive... an atom is most stable when its outermost energy level is full of electrons. The noble gases are exceptions to this general rule.
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What is an ion? Can a compound be ionic?
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An ion is an atom or a molecule that has one or more positive charges or one or more negative charges as a result of the loss or gain (respectively) of one or more electrons. Many compounds can be ionic... a good example is an amino acid (see next topic on biomolecules).
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What is the principal difference between a covalent bond and an ionic bond?
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A covalent bond involves the sharing of a pair of electrons between two atoms, whereas an ionic bond is an electrical attraction between ions of opposite charge.
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Order the following atoms according to increasing electronegativity: carbon, hydrogen, oxygen, and nitrogen.
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hydrogen, carbon, nitrogen, oxygen
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(a) The bonds within a single water molecule are (—?—) bonds. (b) The bonds between many water molecules are (—?—) bonds.
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(a) covalent (b) hydrogen
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What can you say about two atoms joined by a nonpolar covalent bond? Give one example of such a molecule.
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Two atoms joined by a nonpolar covalent bond must be either identical atoms (and thus their electronegativities are equal) or two different atoms with identical electronegativities. An example of a molecule with a nonpolar covalent bond is hydrogen gas... H2(g).
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(a) Which of the following bonds are the strongest (require the most energy to break): double covalent, triple covalent, ionic, hydrogen, single covalent. (b) Which of those bonds is the weakest?
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(a) triple covalent (b) hydrogen
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(a) What is a hydrophilic molecule? (b) What makes a molecule hydrophilic?
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(a) A hydrophilic molecule is a molecule that can easily interact with water and can be readily dissolved by water. (b) The polarity (or charge, if ionic) of a molecule makes it hydrophilic.
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What is the difference between cohesion and adhesion?
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Cohesion refers to the attraction between identical molecules. Adhesion refers to the attraction between different molecules.
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Why is does ice float on liquid water?
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Ice floats on liquid water because it is less dense than liquid water. The difference in density is due to the maximization of hydrogen bonding between water molecules in water ice. With 4 hydrogen bonds per molecule, the individual water molecules a relatively far apart in comparison to liquid water molecules.
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What is the difference in hydrogen ion concentration between a solution at pH 8 and a solution at pH 4?
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There is 104 or 10,000-fold difference in [H+] between the two solutions.
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Which is more acidic, a solution at pH 5 or a solution at pH 8?
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The solution at pH 5 is more acidic than the solution at pH 8.
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When water ionizes to H+ and OH-, is the reaction catabolic or anabolic?
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The solution at pH 5 is more acidic than the solution at pH 8.
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