CHEMISTRY 1451 EXAM 1 (CH 1 & 2) questions with correct answers

CHEMISTRY 1451 EXAM 1 (CH 1 & 2) |\ |\ |\ |\ |\ |\ |\ |\




questions with correct answers |\ |\ |\




size of atom = - CORRECT ANSWERS ✔✔radius of a
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sphere


atom has - CORRECT ANSWERS ✔✔an equal number of
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protons and electrons |\ |\




electrons are - CORRECT ANSWERS ✔✔smaller than
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protons and neutrons |\ |\




electrons = - CORRECT ANSWERS ✔✔the size of atom
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an atom itself is an - CORRECT ANSWERS ✔✔*electrically
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neutral* object (no net charge: number of protons =
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number of electrons) |\ |\




Atomic number (Z) - CORRECT ANSWERS ✔✔number of
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protons and electrons |\ |\




the big four - CORRECT ANSWERS ✔✔*NOCH
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,-NITROGEN
-OXYGEN
-CARBON
-HYDROGEN*


mass number (A) - CORRECT ANSWERS ✔✔number of
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protons + number of neutrons|\ |\ |\ |\




(atomic number (z) + number of neutrons (n)
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A=Z+N
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atomic notation - CORRECT ANSWERS ✔✔
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Isotopes - CORRECT ANSWERS ✔✔-atoms who has the
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*same number of protons* (atomic number is the same)
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-but *different number of neutrons* (mass number is
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different)


neutrons = - CORRECT ANSWERS ✔✔mass # (# of
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protons and neutrons) - atomic # (protons)
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natural abundance - CORRECT ANSWERS ✔✔percent
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distribution of isotopes in a "typical" sample |\ |\ |\ |\ |\ |\

,-how many (%) of isotopes in ex: chlorine
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how many 13^carbon are present in 1000 carbon atoms?
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carbon13 : (natural abu) 1.10% : (mass) 13.00 amu -
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CORRECT ANSWERS ✔✔11 |\ |\




what is the atomic mass? - CORRECT ANSWERS ✔✔an
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element's atomic mass is the *average *of the masses of
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naturally occurring *isotopes* *weighted by natural
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abundances*


When you have 1000 carbons atoms, then
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12^C (mass = 12.00 amu): 989
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13^C (mass = 13.00 amu): 11
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What is the average mass of 1000 carbon atoms? -
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CORRECT ANSWERS ✔✔12.01 amu |\ |\ |\




Calculate the atomic weight of rubidium, which has two
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isotopes with the following properties: 85^Rb (84.91
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amu, 72.71% natural occurrence) and 87^Rb (86.91 amu,
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, 27.83% natural occurrence). Round your answer to 4
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significant figures. - CORRECT ANSWERS ✔✔85.47 amu
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H - CORRECT ANSWERS ✔✔hydrogen
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He - CORRECT ANSWERS ✔✔Helium
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Li - CORRECT ANSWERS ✔✔Lithium
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Be - CORRECT ANSWERS ✔✔Beryllium
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B - CORRECT ANSWERS ✔✔Boron
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C - CORRECT ANSWERS ✔✔Carbon
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N - CORRECT ANSWERS ✔✔Nitrogen
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O - CORRECT ANSWERS ✔✔Oxygen
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F - CORRECT ANSWERS ✔✔Flourine
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Ne - CORRECT ANSWERS ✔✔Neon
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