Download Academic Chemistry Midterm Study Guide Chapters 1

Academic Chemistry
Midterm Study Guide
Chapters 1-4
*Midterm is on Wednesday, January 14, 2015*
Chapter 1: Measurement
Vocab
measurement- includes a number and unit
scientific notation- shorthand method for expressing very large or small numbers
accuracy- how close a measurement is to the true value
precision- how close a series of measurements are to one another
percent error- a calculation that shows how close an experimental value is to the accepted value
exact value- a counting number or pre-defined value
measured value- a value obtained through measurement that has error associated with it
significant figure- a digit that shows the precision of a measurement
conversion factor- a ratio of equivalent measures
dimensional analysis- a problem solving method that relies upon canceling units
density- a ratio of mass to volume
1. a. What is the formula for calculating percent error?
|Experimental value - accepted value|
x 100
Accepted value
b. The density of a cube of gold was calculated to be 18.9 g/cm3. Calculate the percent error if the
accepted value for the density of gold is 19.3 g/cm3. Show all work.
|18.9 g/cm3 - 19.3 g/cm3 |
19.3 g/cm3
x 100
Answer: 2.07%
2. Identify the following as either an exact (E) or measured (M) number.
a. 4 chairs __E___
b. 6.24 liters _M____
c. 12 items = 1 dozen __E__
3. Identify the number of significant figures for the following numbers,
a. 7.04 ___3________
b. 0.01234 ____4_____
c. 3.14 ___3_____
d. 5,000 ___1______
e. 2,000,000. ___7______
4. Perform the following calculations with the correct number of significant figures.
a. 7.04 + 12.2 = ___19.2_________
b. 1.29 x 12.14 = ____15.7_________
c. 5,600/ 8.30 = ____670_________
d. 456 – 3.213 = _____453_________
5. Round the following number to the correct number of significant figures.
324,780,555
a.
b.
c.
d.
6.
1 sig fig ____300,000,000____________________________
2 sig figs ___320,000,000____________________________
3 sig figs ___325,000,000____________________________
4 sig figs ___324,800,000____________________________
Give the SI base units for the following quantities:
a. temperature: ___Kelvin___________________
b. time: ____second______________
c. amount of substance: ____mole_________
d. length: __meter___________
e. mass: ___kilogram________________
7. The freezing point of water is 0°C. Express this temperature in Kelvin (K). Show all work including the
formula used.
°C + 273 = K
0°C + 273 = 273 K
8. a. What is the formula for density? D = m/V
b. Calculate the density of diet coke if the mass of the diet coke is 24.8g and the volume is 25.0mL. Show
all work. m = 24.8g
V = 25.0mL
D = m/V
D = 24.8g/ 25.0mL
D = 0.992 g/mL
c. A lime with a mass of 1.2g is placed in the diet coke from #8b. The volume of diet coke rises to 29.4mL
after the lime has been added. What is the density of the lime? Show all work.
m = 1.2g
V = 29.4mL - 25.0mL = 4.4mL
D = 1.2g/4.4mL
D = 0.27 g/mL
9. Convert each measurement to the unit indicated. Show all work using dimensional analysis (also called
the factor-label method). Write your final answer in scientific notation.
a. 456 m  ______________ km
456 m x
1
1 km
=
Scientific Notation: 4.56 x 10-1 km
0.456 km
1000 m
b. 1927 mL  ______________ L
1927 mL x
1
1L
=
Scientific Notation: 1.927 x 100 L
1.927 L
1000 mL
c. 1.23 kg  _____________ mg
1.23 kg x
1
1,000,000 mg
=
1,230,000 mg
Scientific Notation: 1.23 x 106 mg
1 kg
d. 3345 mm  ___________ cm
3345 mm x
1
1 cm
=
334.5 cm
Scientific Notation: 3.345 x 102 cm
10 mm
Chapter 2: Matter
Vocab
chemistry- study of matter and its changes
matter- anything that has mass and takes up space
mass- the amount of matter contained within an object
weight- a measure of the amount of gravitational force exerted on an object
element- a pure substance that cannot be broken down chemically
atom- the smallest unit of an element that retains the properties of that element
molecule- two or more atoms of the same or different elements chemically bonded
compound- two or more atoms of different elements chemically bonded
mixture- two or more substances physically held together
heterogeneous mixture- non-uniform or unevenly distributed mixture
homogeneous mixture- uniform or evenly distributed mixture
physical property- a property that can be observed without changing the identity of the object
chemical property- a property that when observed changes the identity of the object
physical change- a change in which one or more physical properties is altered, but the chemical identity is not
chemical change- a change in which a substance is changed into a different substance with new properties
law of conservation of mass- mass cannot be created or destroyed; therefore, in a physical or chemical change,
the mass of the reactants should equal the mass of the products
10. Give two examples of each:
a. element- ___oxygen, carbon, copper, iron, etc.________________
b. molecule- ___O2, H2, CO2, CO, etc.__________________________
c. compound- __CO2, H2O, NaCl, etc.___________________________
d. heterogeneous mixture- __trail mix, salad, pizza, etc.____________
e. homogeneous mixture-___Kool-aid, sugar water, salt water, juice, etc.
f.
physical property- __color, odor, texture, shape, size, etc.________
g. chemical property-___reactivity, flammability, etc.______________
11. Identify each of the following as a physical or chemical change.
a. plants converting water and carbon dioxide to oxygen and sugars in the presence of sunlight
_____chemical____________________
b. dissolving salt in water ____physical____________________
c. crushing an ice cube __physical______________________
d. rust forming on a car ___chemical___________________
12. a. What are the three basic states of matter? solid, liquid, gas
b. Draw the three states of matter at the particle level.
c. Describe the motion of particles for each state of matter.
solids - vibrational motion
liquids- particles are more freely moving and slip past each other
gases - particles are freely moving and spread out to occupy the space they are in
Chapter 3: Atomic Structure
Vocab
proton- positively charged subatomic particle
neutron- subatomic particle with no charge
electron- negatively charged subatomic particle
atomic number- equal to the number of protons within an atom
mass number- equal to the number of protons and neutrons found within the nucleus of an atom
isotope- refers to atoms of the same element that have different numbers of neutrons
average atomic mass- weighted average that accounts for the mass and abundance of all naturally occurring
isotopes for a given element
atomic mass unit- equal to 1/12 the mass of a carbon atom
Avogadro’s number- 6.02 x 1023
molar mass- the mass in grams of 1 mole of a given element or compound
13. Briefly summarize the following scientists’ ideas about atomic theory:
a. Democritus- Greek philosopher who believed atoms were indivisible & indestructible
b.
Dalton- scientist who believed that atoms were indivisible, all atoms of a given element were
identical, and that atoms could be joined or rearranged to form compounds
c. J.J. Thomson- scientist who proposed the plum pudding model in which there was a sphere of
positive charge with negatively charged particles embedded throughout
d. Rutherford- scientist who used the gold-foil experiment to show that all of the positive charge
was concentrated in a small, dense nucleus in the center of the atom
e. Bohr- scientist who proposed that electrons orbited around the nucleus at specific energy levels
and could transition between these energy levels
f.
Schrodinger- scientist who proposed the electron cloud model and stated that it is not possible
to know the exact location of an electron at any given time
14. Determine the number of protons, neutrons, and electrons for the elements below.
a. silver
#protons: __47_____
#neutrons: _61______ #electrons: _47_____
b. sulfur
c. potassium
#protons: _16______
#protons: __19_____
#neutrons: _16______ #electrons: _16_____
#neutrons: _20______ #electrons: _19_____
d. helium
#protons: _2______
#neutrons: _2______
15. a. What is the formula used to calculate average atomic mass?
#electrons: __2____
Average Atomic Mass = (mass x (abundance/100)) + (mass x (abundance/100)) ...
Isotope #1
Isotope #2
b. What is average atomic mass of Lithium if 7.42% exists as 6Li (6.015 amu) and 92.58% exists as 7Li
(7.016 amu)?
Average Atomic Mass = (6.015 amu x (7.42/100)) + (7.016 amu x (92.58/100))
Average Atomic Mass = 0.446 amu + 6.495 amu = 6.941 amu
16. Draw a Bohr model for Aluminum (Al).
17. How many moles is 4.14 x 1023 atoms of copper (Cu)? Show all work.
4.14 x 1023 atoms
x
1 mol______ = 0.688 mol
6.02 x 1023 atoms
1
18. How many atoms are 9.11 mol of carbon (C)? Show all work.
9.11 mol
x
1
6.02 x1023 atoms = 5.48 x 1024 atoms
1 mol
19. What is the molar mass of Ba(NO3)2? Show all work.
1 atom Ba x (137.33 g/mol) = 137.33 g/mol
2 atoms N x (14.00 g/mol) = 28.00 g/mol
6 atoms O x (16 g/mol) = 96 g/mol
Molar Mass = 137.33 g/mol + 28.00 g/mol + 96 g/mol = 261.33 g/mol
20. How many grams are in 8.55 mol of carbon dioxide (CO2)? Show all work.
Molar Mass of CO2 =( 1 atom C x 12.011 g/mol) + (2 atoms O x 16 g/mol) = 44 g/mol
8.55 mol
1
x
44 g
1 mol
= 376.2 g
21. Find the number of moles in 609g of iron (Fe). Show all work.
Molar Mass of Fe = 55.845 g/mol
609 g
x
1
1 mol
*look up on periodic table
= 10.9 mol
55.845 g
22. Find the number of atoms in 377g of calcium (Ca). Show all work.
Molar Mass of Ca = 40.078 g/mol
377 g
1
x
1 mol
40.078 g
*look up on periodic table
x
6.02 x 1023 atoms = 5.66 x 1024 atoms
1 mol
Chapter 3.3: Electrons in Atoms
Vocab
atomic orbital- region where electrons are likely to be found
Aufbau principle- principle that states the electrons will occupy energy levels of lowest energy first
Pauli Exclusion principle- principle that states that only 2 electrons of opposite spin may fill an orbital
Hund’s rule- rule that states that electrons will fill orbitals to maximize the number of electrons with the same
spin direction
electron configuration- the way in which electrons are arranged around the nucleus of an atom
wavelength- the distance between two crests of a wave
frequency- the number of wave cycles per unit of time
speed of light- constant; 3 x 108 m/s
atomic emission spectrum- the specific frequencies of light emitted by an atom
23. Identify what each of the following below indicate for the given electron configuration,
1s2 2s2 2p6 3s2 3p6 4s2 3d5
a. What do the numbers 1, 2, 3 & 4 represent? ___energy levels____________
b. What do the letters s,p &d represent? ___energy sublevels_______________
c. What does the sum of the superscripts equal? __atomic number___________
24. An atom of an element has two electrons in the first energy level, 8 electrons in the second energy level,
and 3 electrons in the third energy level.
a. Write the electron configuration for this atom.
1s2 2s2 2p6 3s2 3p1
b. Name the element. Aluminum
c. How many unpaired electrons does an atom of this element have? 1
25. What is the wavelength of radiation whose frequency is 3.00 x 1015 Hz? Show all work.
speed of light = wavelength x frequency
c= λν
3 x 108 m/s = λ (3.00 x 1015 Hz)
Divide both sides by (3.00 x 1015 Hz)
λ = 1.00 x 10-7 m
26. What is the frequency of radiation whose wavelength is 290 cm? Show all work.
c= λν
*must convert 290cm to meters first
290cm x
1
3 x 108 m/s = (2.9m) ν
ν = 1.03 x 108 1/s or Hz
1m
100cm
Divide both sides by (2.9m)
= 2.9 m
Chapter 4: The Periodic Table
Vocab
anion- negatively charged ion
atomic radius- 1/2 the distance between the nuclei of two bonded atoms
cation- positively charged ion
electronegativity- the ability of an atom to attract electrons when bonded
ion- a particle with a negative or positive charge; forms when an atom loses or gains electrons
ionization energy- the amount of energy needed to remove an electron from an atom or ion
periodic law- a law that states when elements are arranged according to increasing atomic number, there is a
periodic repetition of physical and chemical properties
27. Label the following on the periodic table:
metals- to the left of the staircase
nonmetals- to the right of the staircase
metalloids-along the staircase
alkali metals-group 1
alkaline earth metals-group 2
halogens-group 17
noble gases-group 18
1
1
2
3
4
5
6
7
13 14 15 16 17 18
2
3 4 5 6 7 8 9 10 11 12
periods #1-7
groups #1-18
transition metals-groups 3-12
28. Compare and contrast the way in which Mendeleev organized his periodic table to the way in which the
modern periodic table is arranged.
Mendeleev organized the elements by increasing atomic mass while the modern periodic table arranges
the elements by increasing atomic number.
29. Explain why the elements fluorine and chlorine have similar chemical properties.
Both fluorine and chlorine are halogens and have seven valence electrons.
30. Complete the following information for boron (B).
a. Electron configuration: 1s2 2s2 2p1
b. Group #: 13
c. Number of electrons in highest occupied energy level: 3
31. Use arrows to show the following periodic trends on the periodic table provided.
a. decreases------------------------------
c. increases ----------------------------
c. electronegativity
32. Arrange these elements in order of increasing atomic size:
xenon (Xe), helium (He), strontium (Sr), argon (Ar), magnesium (Mg)
helium < argon < magnesium < xenon < strontium
33. Which element has the larger first ionization energy?
iodine or chlorine
Lab Procedures & Safety
34. Draw each of the following…. I’m not grading on artistic ability so just try your best 
a. beaker
b. graduated cylinder
c. Erlenmeyer flask
d. plastic pipet
a. increases ------------------------
b. ionization energy
b. decreases ---------------------
b. increases ----------------------------
c. decreases --------------------
a. atomic size (radius)
e. Bunsen burner
f.
ring stand
g. iron ring
h. evaporating dish
35. Explain the steps needed to successfully light a Bunsen burner and obtain a blue (non-luminous) flame.
1. Turn on the gas, use striker to light
2. Adjust the gas to produce a flame of proper height
3. Open the air holes until a blue flame is produced
36. List five safety rules that must be followed at all times during a lab.
1. Safety goggles should be worn at all times
2. Long hair should be tied back
3. Never bring food or drinks into the lab area
4. Follow all directions given by the teacher and written in the lab procedure
5. Dispose of all chemicals in the designated waste container or as directed by the teacher
37. If you obtain too much of a chemical from the stock container, explain how you should proceed.
Excess chemicals should never be placed back in the original container. They should be disposed of in
the proper waste container or as directed by the teacher.
38. List three things found in the lab area that are there for your safety.
Safety shower, eye wash station, fire blanket, goggles, fire extinguisher, etc.