Transcript Semester I Review

Semester I Review
ANSWERS
Semester I Review

How many sig-figs are found in each
number?
 0.345
 3005
 300
 3.002
 0.00023
3
4
1
4
2
Semester I Review
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Round each number to three sig-figs.
 45678
 0.002894
 23.76
 100.5
 56.799
45700
0.00289
23.8
100.
56.8
Semester I Review
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Which of the following is a mixture.
 Pure
water compound
 Clean air
homogenous mixture
 Iron (II) oxide compound
 Salt water homogenous mixture
 Carbon dioxide compound
Semester I Review
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Which of the following is a chemical
change.
 Cutting
paper
 Boiling water
 Rusting iron
 Burning gasoline
physical
physical
chemical
chemical
Complete the table using the given
numbers
Symbol
X - _25__
Mass #
Atomic #
25
10
Y - 35
35
Z - _56__
56
Protons
Neutrons
Electrons
10
15
10
14
14
21
14
25
25
31
25
Semester I Review
Calculate the average atomic mass given
the following data: element Y has three
isotopes 35.0% = 23.5 amu, 55.0% = 25.0
amu and 10.0% = 26.0 amu.
 (35x23.5) + (55x25.0) + (10x26.0) = 24.6
100
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Semester I Review
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25.0 grams of a given metal displaces
44.2 mL of water; what is the density of the
metal?
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25.0g/44.2mL = 0.566g/mL
Semester I Review
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What did each scientist contribute to the
development of the modern atom.
 Dalton
= proof of the atom
 Thomson = cathode rays are electrons
 Rutherford = dense positive nucleus,
electrons outside nucleus, atom mostly empty
space
 Milliken = mass to charge ratio of the electron
Determine if the data below is
accurate, precise, both, or neither
Trial #
Measurement
1
34.56
2
34.45
3
34.78
True Value = 34.50
Accurate
and
precise
Calculate the percent error using the average
of the measurements. (34.60 – 34.50) x100 = 0.2899%
34.50
Semester I Review
1.
2.
3.
The splitting of a nucleus is known as
___fission _____.
The combining of two small nuclei to form a
larger one is known as ____Fusion______.
Give the formula of an alpha particle and beta
particle.
4
2
He
0
1

Semester I Review
1.
Decay of polonium-218 by alpha ()
emission.
1.
2.
3.
4.
5.
218
84
Po
214
He

+ 82 Pb
4
2
Decay of carbon – 14 by beta emission
14
14

C

+
6
7N
Decay of Thorium - 232 by an electron
capture
232
  89 Ac
Th +
0
1
232
90
0
1
Semester I Review
1. The half-life of phosphorous-30 is 2.5
min. If you start with 55 g of
phosphorus-30, how many grams would
remain after 27.5 min?
 Mfinal = (55g)(.5)11 = 0.027g
Semester I Review
A radioactive isotope decayed from 200.0
grams to 3.125 grams in 15 years.
Determine the half-life of the isotope.
3.125g = 200.0(0.5)X
64 = 2X
X = 6, so 6 half-lives have passed in 15
years. Therefore each half-life is 2.5 years
long
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Semester I Review
Calculate the wavelength of
electromagnetic radiation with a frequency
of 6.5x1016 Hz.
4.6x10-9 m
 Calculate the energy of the above
electromagnetic radiation.
4.3x10-17 J
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Semester I Review
If n=4; how many sublevels 4, Orbitals 16,
and Electrons are present 32?
 T or F (p) sublevels have 7 orbitals
 T or F (d) sublevels hold only 6 electrons
 T or F (s) sublevels hold 2 electrons
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Semester I Review
For the element Cobalt; give the:
 Long hand electron configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d7
 Box and arrow notation
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Noble gas configuration
[Ar] 4s2 3d7
 Electron Dot Structure
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Semester II Review
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•
•
Which of the following elements has
the smallest first ionization energy:
potassium or calcium?
Which of the following has the
smallest atomic radius: O or S?
The energy required to remove an
electron from a gaseous atom is
called the Ionization energy.
Semester II Review
•
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
Atomic size generally decreases as you
move left to right in a period.
How does atomic radius change down a
group in the periodic table?Increases
How does ionization energy change as
you move up and to right on the periodic
table? Decreases up and increases to the
right
Semester II Review
Sheilding will increase as you go down a
group.
 Sheilding will remain constant as you
move left to right across a period.
 Electronegativity will decrease as you
move down and to the left.
 Columns on the periodic table are known
as groups or families.
 Rows on the table are known as periods.
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