Chemistry Quarter 1 Midterm Review Sheet
Chapter 1
1. What is matter?
Anything that takes up space and has a mass
2. Define the following terms: dependent (responding) variable, independent (manipulated) variable, controlled variable, hypothesis and theory.
Chapter 2
3. Make a chart showing the properties of solids, liquids, and gases. Include the following: definite shape or not, definite volume or not, and how tightly packed the particles are.
Solid: definite shape and volume
Liquid: indefinite shape and definite volume
Gas: indefinite shape and volume
4. What is a vapor?
The gaseous phase of a substance that is typically a solid or liquid at room temperature.
5. List five physical changes.
Change in phase, shape, size, mass, volume
6. What distinguishes a chemical change from a physical change?
A chemical change involves the creation of a new substance with new properties, where a physical change doesn’t change the properties of the substance and nothing new is created.
7. List 4-5 indicators that a chemical change is occurring.
Odor change, temperature change, fizzing (creation of a gas), obvious new substance
8. Contrast mixture and pure substance.
Mixture: one or more substances together physically, pure substance: all one type of substance or particle
9. Is it possible to have a mixture in the gas phase or solid phase? Explain.
Yes—air is a mixture of different types of gases and particulate matter. Stainless steel and other alloys are solid mixtures as well as Lucky Charms and soil from outside. These examples are not chemically bonded.
10. Draw a picture showing a homogeneous mixture and a heterogeneous mixture.
11. What properties are used to separate mixtures in the processes of filtration and distillation?
Filtration: particle size Distillation: boiling point
12. List five elements and five compounds.
Elements: helium, carbon, uranium, manganese, neon
Compound: sodium chloride, water, carbon dioxide, methane, calcium sulfate
13. What is the law of conservation of mass? Rewrite the definition in easy to understand terms.
Matter cannot be created or destroyed in a chemical reaction. In other words, chemical bonds break and reform in a different pattern using all the same atoms.
Chapter 3
14. Contrast accuracy and precision. Draw a diagram to support your answer.
Accuracy: data points are close to the target value
Precision: data points are close to one another
15. Write the following in scientific notation:
16. (a) 34700 3.47 x 104 (b) 7856000 7.856 x 106
17. (c) 0.0034 3.4 x 10-3
18. Write the following in long hand notation:
19. (a) 4.5 x 108 450,000,000 (b) 3.5 x 10-5 0.000035
20. How many milliliters are in a liter? 1000 ml
21. How many grams are in a kilogram? 1000 g
22. How many centimeters of yarn do you have if you have 2.5 meters? 250 cm
23. What is the metric base unit for the following:
(a) temperature Kelvin (b) mass kilogram (c) distance meter
24. What is the density of a metal that has a volume of 35 cm3 and a mass of 350 grams?
10 g/ cm3
25. What is the volume of a 40 g sample, which has a density of 8 g/mL? 5 mL
26. In 2001, the average commute time in the Bay Area was 29 minutes. Assume that a commuter averages 40 miles/hour on the freeway. How many miles was the average commute?
19.3 miles
27. Using the equivalence statement, 1.61 km = 1 mile, how many kilometers was the average commute? 31.1 km
28. The price of gasoline was an average of $2.00/gallon in San Francisco in 2001 (Can you believe it?). How much did the average commuter spend per week on gas?
We don’t have enough information. We would need to know how much mileage the car gets.
Chapter 4 & Chapter 5
29. Describe the atomic theories of Democritus, Dalton, JJ Thomson, Rutherford, Bohr, and Schrodinger (electron cloud). Include a drawing for each and the name of their model.
Please use your notes for this one…
30. How did the cathode ray tube contribute to our knowledge of the atom?
It allowed Thomson to see the beam produced was made of electrons and he discovered the first subatomic particle-the electron.
31. Describe Rutherford’s gold foil experiment and what conclusions were drawn from it.
Positive alpha particles were passed through a thin piece of gold foil. Most particles pass straight through suggesting the atom was mostly empty space. A few particles were deflected at various angles showing that there was a very small positive center—he called it the nucleus.
32. Contrast the Bohr model and the Quantum Mechanical Model (electron cloud model) of the atom. Bohr model: electrons travel around the nucleus in fixed planar orbits like planets around the sun. QMM: electrons travel around the nucleus in 3D orbitals, which represent the probable location of the electrons.
33. Draw an atom, showing the protons, neutrons, and electrons. Indicate the charge on each and their relative masses.
electron mass = 0
proton mass = 1
neutron mass = 1
34. Compare the size and mass of the nucleus to the whole atom.
The size of the nucleus is tiny compared to the entire atom yet all the mass of the atom is in the nucleus.
35. How many protons, neutrons, and electrons are in a neutral atom of Iron-56?
p = 26, n = 30, e = 26
How many protons, neutrons, and electrons are in a neutral atom of 28Si?
p = 14, n = 14, e = 14
How many protons and electrons are in Mg2+? p = 12, e = 10
36. What are isotopes? Atoms of the same element, but with different numbers of neutrons and different masses What are ions? Atoms with a positive or negative charge.
37. The average atomic mass of strontium is 87.62. If it has two isotopes, strontium-87 and strontium-88, which is more abundant? Explain.
Sr-88 because the average mass is closer to 88 than 87
38. Calculate the average atomic mass for an element that has three isotopes. The first has an atomic mass of 11.95 amu and represents 35% of the sample, the second has an atomic mass of 12.97 amu and represents 35% of the sample, and the third has an atomic mass of 13.94 amu and represents 30% of the sample. Show your work! 12.9 amu
39. How many valence electrons do the following have:
(a) sodium 1 (b) chlorine 7 (c) neon 8
40. Write the long hand electron configuration for aluminum. Write the noble gas notation for iodine. Al: 1s2 2s2 2p6 3s2 3p6 3p1 I: [Kr] 5s2 4d10 5p5
41. Draw a diagram showing a light wave. Label wavelength.
42. How does wavelength relate to frequency? The longer the wavelength, the lower the frequency of a wave. How does this relate to the color of the light? Long wavelengths are associated with red and orange, and short wavelengths are associated with blue and violet.
43. Describe the activity of electrons that causes atomic emission spectra. When electrons gain energy they can move to a higher energy level, as electrons move down to a lower energy level they release energy sometimes in the form of light.
44. Define quantum and photon. A quantum is the minimum amount of energy an electron needs to move to a higher energy level. A photon is a particle of light.
45. Sketch a periodic table and label the principal energy levels and s-f blocks.
46. How many orbitals are in the s, p, d, and f orbitals? How many electrons can each hold?
s 1 orbital 2 electrons
p 3 orbitals 6 electrons
d 5 orbitals 10 electrons
f 7 orbitals 14 electrons
47. Sketch the 1s, 2s, and the three 2p orbitals. What do we call these shapes?
spherical and dumb bell
Chapter 6
48. Who first organized the modern periodic table? Mendeleev What changes did Henry Moseley make? Moseley reorganized the PT by increasing atomic number.
49. What do we call the following groups (families) on the periodic table: group 1A alkali metal, group 2A alkaline earth metal, group 7A halogen, group 8A noble or inert gas?
50. What do we call the elements in the d and f blocks? Transition metals/B group elements
51. Where on the periodic table are the metals, metalloids, and non-metals?
52. Make a chart contrasting the metals and nonmetals.
Metals: conduct electricity, malleable, electron donors, shiny, react with HCl and CuCl2
Nonmetals: do not conduct electricity, brittle, electron acceptors, dull, do not react with HCl and CuCl2.
53. What happens to reactivity as you move down a group or column on the periodic table? On the left side of the PT reactivity increases as you move down a group. On the right side of the PT, reactivity increases as you move up a group.
54. Why do elements in the same group have similar properties? The elements have the same number of valence electrons and those are the electrons that are involved in chemical reactions.
55. Draw three periodic tables (outline only!). Draw arrows showing the trends for atomic radius, ionization energy, and electronegativity.
56. Why do atoms get smaller as you move across rows of the periodic table? The increase in number of protons has an increase of attraction for each electron, pulling the electrons in.
57. Why do atoms get larger as you move down columns of the periodic table? Increase in number of energy levels and shielding of the outer electrons by the inner electrons.
58. What causes some elements to have a strong pull on electrons, while others have less of a pull? Typically the smaller atoms have a higher electronegativity because the electrons can get closer to the nucleus.
59. Why are the trends for ionization energy and electronegativity similar? The atoms that are attractive to electrons tend to require lots of energy to let an electron go.
60. What happens to the size of an atom when it forms a cation (positive ion)? The cation is smaller in radius than its neutral atom. What happens to the size of an atom when it forms an anion (negative ion)? The anion is larger in radius than its neutral atom. Draw a diagram to support your answer.
Chapter 25
61. Where in the atom does radiation come from? The nucleus
62. What are the nuclear symbols and charges for the 3 types of radiation?
63. List the three types of radiation from lightest in mass to heaviest. Alpha, beta, gamma
64. What types of materials will each type of radiation be able to penetrate?
65. Write the equation for U-238 going through alpha decay, and then write the equation for the beta decay of the resulting daughter isotope.
Note that this example includes gamma as well as beta.
Note that this decay series also includes the next step in the decay of uranium, which the question does not address.
(# 66 on back)
66. Compare a fission reaction to a fusion reaction.
/ Nuclear Fission / Nuclear Fusion /Definition: / Fission is the splitting of a large atom into two or more smaller ones. / Fusionis the fusing of two or more lighter atoms into a larger one.
Conditions: / Critical mass of the substance and high-speed neutrons are required. / High density, high temperature environment is required.
Energy Requirement: / Takes little energy to split two atoms in a fission reaction. / Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
Energy Released: / The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion. / The energy released by fusion is three to four times greater than the energy released by fission.