Chemistry 130 Test 1 Study Guide

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  1. What are the steps to the scientific method, in order?
    • 1) Make observations, recognize patterns
    • 2) Formulate a law, theory, or hypothesis based on observations
    • 3) Conduct experiments to test the validity of the law, theory or hypothesis.
  2. What is the difference between scientific law and a theory?
    A law summarizes what happens, a theory tries to explain why it happens.
  3. What does hypothesis mean?
    A developed idea that tries to explain the patterns and results of observations.
  4. Define matter.
    Anything that occupies space and has mass ("stuff").  

    Matter exists in three different states: solid, liquid, and gas.
  5. Define mass.
    A measure of the quantity of matter within an object.
  6. Define weight.
    A body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.
  7. Define properties.
    The characteristics used to distinguish one substance from another.
  8. Define substance.
    A form of matter that has a definite composition and distinct properties.
  9. Define composition.
    The types and amounts of simpler substances in a sample.

    Example:  Water is always 1/9 Hydrogen by mass and 8/9 Oxygen by mass.
  10. What is atomic theory and who discovered it?
    A theory stating that all matter is composed of tiny indestructible particles called atoms.

    Atoms of one substance cannot be changed into atoms of another substance.

    It was discovered by John Dalton.
  11. Define molecule.
    A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
  12. Define atom.
    The basic unit of a chemical element.

    The smallest piece of any element is a single atom of said element.
  13. For addition and subtraction, the quantity with the fewest _______ determines the number of decimal places in the answer.
    decimal places
  14. For multiplication and division, the quantity with the fewest _______ determines the number of significant figures in the answer.
    significant figures
  15. Define accuracy.
    How close a measurement, or the average of several measurements, is to the true answer.
  16. Define precision.
    How exactly or sharply a measurement is reported, or how closely several measurements agree with each other.
  17. Is the following accurate, or precise?


    ("|" are measurements taken, X is true)
    Accurate (fair accuracy, poor precision).
  18. Is the following accurate, or precise?


    ("|" are measurements taken, X is true)
    Precise (fair precision, poor accuracy).
  19. Define density.
    Density = mass (g) / volume (cm3 or mL)
  20. To use density as a unit conversion factor in finding volume, how do you set up the equation?
    • Use the inverted density expression, because you're trying to convert to a unit of volume:
    •    1         V (cm3)
    • ------ = -------------
    •    d         m (g)

    So, using a density of 1.32 g/cm3:

    •                (1 cm3)       1 mL
    • 64.84g  *  ---------  *  -------- = 51.8 mL
    •                 1.32 g       1 cm3
  21. What are the three states of matter?
    Solid, liquid, gas
  22. True or false: Many substances exist in all 3 phases, depending on temperature.
  23. What are the properties of a solid?
    *Fixed shape and volume.  Does not conform to the shape or volume of a container.

    *Crystalline or Amorphous.

    *Incompressible because particles are in direct contact with each other.
  24. What are the properties of a liquid?
    *Does not have a fixed shape but does have a fixed volume.

    *Liquids are like amorphous solids in structure.

    *Incompressible because particles are in direct contact with each other.
  25. What are the properties of a gas?
    *Does not have either a fixed shape nor a fixed volume.

    *Large spaces between molecules.

    *Compressible (unlike liquids or solids)

    *Density is much lower for all substances than that of corresponding liquid or solid.

    *Most of a gas sample is empty space.
  26. Define crystalline solids.
    The constituent particles (molecules or atoms) repeat in a regular fashion in all three dimensions.

    An example of this is NaCl, Sodium Chloride.
  27. Define amorphous solids.
    The constituent particles (molecules or atoms) do not repeat in a regular fashion.

    An example of this is glass.
  28. True or False:  Solids and liquids have similar densities.
  29. Define pure substance.
    A substance composed of only one type of atom or molecule.
  30. Define mixture.
    A substance composed of two or more different types of atoms or molecules combined in variable proportions.
  31. Define compound.
    A substance composed of two or more elements in fixed definite proportions.
  32. Define element.
    A substance composed of only one type of atom.  It cannot be broken down into simpler substances.
  33. Define heterogeneous mixture.
    The composition of the mixture varies from one region to another.

    (Oil and water).
  34. Define homogeneous mixture.
    The composition of the mixture is the same throughout.

    (Salt water or sweetened tea).
  35. Physical or chemical change: wood burning.
  36. Physical or chemical change: bending an iron nail.
  37. Define physical property.
    A property that a substance displays without changing its composition.
  38. Define chemical property.
    A property that a substance displays only through changing its composition.
  39. Is the odor of gasoline a physical or chemical property?  Why?
    Physical.  Gasoline does not change its composition when it exhibits its odor.
  40. Is the flammability of gasoline a physical or chemical property?  Why?
    Chemical.  Gasoline does change its composition when it burns.
  41. Physical or chemical change: water boiling.
    Physical.  It changes from liquid to gas, but the gas is still water.
  42. What are the various forms of energy?
    • Kinetic
    • Potential
    • Electrical
    • Chemical
    • Thermal
  43. Describe kinetic energy.
    Energy of motion.
  44. Describe potential energy.
    Energy associated with position or composition.
  45. Describe electrical energy.
    Energy associated with the flow of electrical charge.
  46. Describe thermal energy.
    Energy associated with the random motions of atoms and molecules in matter.  The hotter an object, the more thermal energy it contains.
  47. Describe chemical energy.
    Form of potential energy associated with the positions of the particles that compose the chemical system.
  48. Define calorie.
    The amount of energy needed to raise the temperature of exactly 1 gram of H2O by exactly 1oC.
  49. Define Calorie.
    1,000 calories = 1 Calorie = 1 kilocalorie.
  50. Define kilocalorie.
    1,000 calories = 1 Calorie = 1 kilocalorie.
  51. What is an exothermic process?
    A process that releases heat energy.
  52. What is an endothermic reaction?
    A chemical reaction that absorbs heat from surroundings.
  53. What is an exothermic reaction?
    A chemical reaction that releases energy to the surroundings.
  54. Define electron.
    A negatively charged particle that occupies most of the atom's volume but contributes almost none of its mass.
  55. Describe the nuclear theory of the atom.
    Most of the atom's mass and all of its positive charge are contained in a small core called the nucleus.

    Most of the volume of the atom is empty space through which the tiny negatively charged electrons are dispersed.

    There are as many negatively charged electrons outside the nucleus as there are positively charged particles (protons) inside the nucleus, so that the atom is electrically neutral.
  56. In an atom, where are protons located?
    The nucleus.
  57. In an atom, where are neutrons located?
    The nucleus.
  58. In an atom, where are electrons located?
    Outside the nucleus.
  59. The number of electrons outside the nucleus is equal to the number of _______ inside the nucleus.
  60. The dense nucleus of an atom makes up more than _______ percent of the mass of the atom, and it contains _______ and _______.
    99.9%; protons; neutrons
  61. What charge do protons have?
  62. What charge do electrons have?
  63. What charge do neutrons have?
    No charge.
  64. Define atomic number.
    The number of protons in the nucleus of an atom.

    This number is unique to each element, and is what defines the element.
  65. Define ion.
    Charged particles formed in a chemical reaction by atoms losing or gaining electrons.
  66. Non-metals _______ electrons in chemical reactions.
  67. Metals _______ electrons in chemical reactions.
  68. Define cation.
    A positively charged ion.
  69. Define anion.
    A negatively charged ion.
  70. Define isotopes.
    Atoms with the same number of protons but different number of neutrons.
  71. Define percent natural abundance.
    The percentage amount of each isotope of an element in a naturally occurring sample of the element.

    For example, Neon Ne, there are 3 different Ne isotopes:

    10 neutrons, 11 neutrons, and 12 neutrons.  10 makes up 90.48% of random natural samples, 11 makes up 0.27%, and 12 makes up 9.25%.
  72. Define mass number.
    The sum of the number of protons and neutrons in an atom.

    It is given the symbol A:

    A = Number of protons + number of neutrons
  73. Describe what each letter represents:

    • a = mass number
    • z = atomic number
    • x = chemical symbol
  74. A secondary common notation for isotopes is:
    Describe each letter.
    • X = chemical symbol
    • A = Mass number
  75. How do you find the number of neutrons in an isotope?
    Subtract the atomic number number from the mass number:

    • a
    •    X
    • z

    # of neutrons = a - z
  76. Define atomic mass.
    The average mass of the atoms that compose an element (of each isotope).
  77. How is atomic mass calculated?
    • Percent natural abundance is converted to decimal form
    • Percent natural abundance is multiplied by the mass
    • This is done for each isotope
    • The totals are summed together
    • This gives atomic mass.
  78. Define molar mass.
    The mass of one mole of atoms of an element or one mole of molecules (or formula units) for a compound.

    An element's molar mass in grams per mole is numerically equivalent to the element's atomic mass in amu.
  79. How do you protect yourself from the harmful effects of each type of radiation?
    Distance yourself from the source and use appropriate shielding:

    • 1) Alpha particles: sheet of paper or thicker
    • 2) Beta particles or positrons: wood or winter clothing or thicker
    • 3) Y rays & X rays: lead shielding
  80. Define radioactivity.
    The emission of tiny, invisible, energetic particles from the unstable nuclei of atoms.

    Many of these particles can penetrate matter.
  81. Define alpha radiation.
    Radiation emitted by an unstable nucleus, consisting of alpha particles.

    •      4
    • a    He   nucleus.
    •      2
  82. Define beta radiation.
    A fast-moving electron that originates in the nucleus from neutron decay; a proton is also formed.

    Energetic electrons emitted by an unstable nucleus.
  83. Define X-rays
    The portion of the electromagnetic spectrum between ultraviolet (UV) region and the gamma-ray region.
  84. Define half-life.
    The time it takes for one-half of the parent nuclides in a radioactive sample to decay to the daughter nuclides.

    The time it takes for a radioactive sample to decay to one-half its original measurement.
  85. Define gamma (Y) radiation.
    High-energy forms of light that are not visible to human eyes.

    High-energy, short-wavelength electromagnetic radiation emitted by an atomic nucleus.
  86. Define positron emission.
    Expulsion of a positron from an unstable atomic nucleus.  In positron emission, a proton is transformed into a neutron.
  87. Define positron.
    Positively charged electrons (an example of antimatter).
  88. Atomic mass and molar mass are _______.
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Chemistry 130 Test 1 Study Guide
2014-02-05 06:06:20
Chemistry 130 Test Study Guide
Chemistry 130 Test 1 Study Guide
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