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Chemistry
Exam 2/ chapters 4,6, and 11
| Term | Definition |
|---|---|
| The major part of the average exposure of humans to radiation comes from | naturally occurring sources |
| Radiation with enough energy to knock electrons off atoms or molecules is known as | ionizing radiation |
| The following nuclear reaction is an example of 226/88 Ra --> 4/2 He + 222/86 Rn | alpha decay |
| Thorium-234 undergoes beta decay 234/90 Th --> 0/1- e + Q....... What is Q | 234/91 Pa |
| When radium-223 undergoes alpha decay, what other product is formed? | radon-219 |
| The process of beta emission can be envisioned as the | conversion of a neutron to a proton and electron. The electron is emitted |
| Phosphorous-30 decays by positron emission. This product is | silicon-30 |
| The process of electron capture can be considered as the | conversion of an electron and a proton to a neutron |
| The process of electron capture results in what change in the atomic number | a decrease by 1 |
| After 5 half lives, what % of the original radioactive isotope remains in the sample? | 3.13% |
| Nitrogen-13 has a half life of 10 minutes. How much of a 128 mg sample would remain after 20 minutes? | 32 mg |
| Exposure to radioactive material is considered safe after 10 half lives because | less than a tenth of 1 % of the material remains |
| Carbon-14 dating of ancient objects is particularly effective because C-14 | is continuously produced in the upper atmosphere and its ratio to C-12 in living systems and the environment is constant. |
| The isotope that is used for the dating of brandy is | hydrogen-3 |
| Radioisotopes have been used as tracers in a variety of applications because | -radioactive isotopes of an element have the same chemical properties as nonradioactive isotopes. |
| Gadolinium-153 is the most widely used radioisotope in medicine. It is used for the detection of | osteoporosis |
| Which type of radioactive emission is very similar to X-rays? | gamma rays |
| Alpha particles can be stopped by a | sheet of paper block of wood thin sheet of aluminum |
| In the famous relationship: E = mc2, the symbol m represents | mass |
| Which process will result in an increase in the binding energy per nucleon? | -fission of large radioactive nuclei -fusion of small nuclei |
| Nuclear fission is a process by which the nucleus of an atom | is induced to split into 2 or more fragments by some external source |
| In nuclear fission | smaller, relatively stable, nuclei are forced together to create a larger nucleus with the release of binding energy |
| The often tedious process by which a naturally occurring mixture of isotopes is separated and concentrated is called | isotopic enrichment |
| UF6 containing uranium-235 can be separated from UF6 containing uranium-238 because | UF6 containing uranium-235 is lighter and will travel faster than UF6 containing uranium-238. |
| Cesium-137 is both produced in nuclear fallout and has a half-life of 30 years. Cesium-137 is capable of long-term effects because it is | chemically similar to potassium and is taken up by living organisms as part of body fluids |
| Give a use for depleted Uranium | make armor plating |
| Which of the following statements about nuclear power plants is NOT true? | The uranium fuel used contains over 90% of 235U. |
| Identify which one was NOT a malfunction at a nuclear power plant | A tornado tore a roof of the cooling plant resulting in a release of radioactive gas |
| After one half-life, 50% of a radioactive sample will remain. After the second half-life, none of the radioactivity will be left | False |
| The ratio of different isotopes of an element, such as oxygen-16 and oxygen-18, will always be the same | False |
| The inertness of the noble gases is due to | The inertness of the noble gases is due to |
| A sodium ion, Na+, has the same electron configuration as a(n) | neon atom |
| The number of electrons in a chloride ion, Cl-, is | 18 |
| When calcium reacts with iodine, calcium ions, Ca2+, and iodide ions, I-, are formed. In this reaction, calcium atoms | lose electrons |
| Which molecule is NOT likely to exist? | Ar2 |
| Which of the following pairs is isoelectronic? | Ar and S2- |
| An electron-dot structure is a convenient method of representing | valence electrons of an atom |
| From the periodic table, the number of valence electrons for most of the main group elements may be determined directly from the | group number |
| Which is the electron dot structure of calcium? | Ca: |
| Which of the noble gases does NOT have an octet of electrons in its outer shell? | He |
| When a freshly cut piece of sodium metal, Na, is dropped into a flask with chlorine gas, a violent reaction takes place creating a new compound. This compound | has properties that are totally unlike either Na or Cl |
| The attraction between positive and negative ions is known as a(n) | ionic bond |
| When ions arrange themselves in an orderly structure, that structure is known as a | crystal |
| When magnesium combines with bromine, the bond formed is best classified as | ionic |
| A nitride ion is | N3- |
| Which atom is least likely to form an ion? | carbon |
| Which atom is least likely to form an ion? | carbon |
| When magnesium reacts with chlorine, the reaction involves a | transfer of electrons from Mg to Cl |
| In reactions to form ionic compounds, metals generally | lose electrons |
| The anion formed when oxygen gains two electrons is called the | oxide ion |
| The name of the compound with the formula AlCl3 is | aluminum chloride |
| The formula for the compound calcium bromide is | CaBr2 |
| How many electrons are there in a double bond? | 4 |
| The prefix which means seven is | hepta |
| A covalent bond is formed when a pair of electrons is | shared |
| If two atoms from the same element share three pairs of electrons in forming a molecule the bond is called a | triple covalent bond |
| Which is the electron dot structure for nitrogen, N2? | :N:::N: |
| What is the name of the compound with the formula CF4? | carbon tetrafluoride |
| Hydrogen is a diatomic molecule, H2. The bond holding the hydrogen atoms together is | nonpolar covalent |
| ________ is the measure of the tendency of an atom in a molecule to attract a shared pair of electrons to itself. | Electronegativity |
| In the hydrogen chloride molecule, HCl, the chlorine end of the molecule is more negative than the hydrogen end because | chlorine is more electronegative than hydrogen. |
| Which substance has polar covalent bonds? | SO2 |
| Which substance has nonpolar covalent bonds? | H2 |
| The most electronegative atom is | F |
| Which substance has covalent bonds? | CO2 |
| Which of the following elements has the lowest electronegativity? | Kr |
| Chalk is primarily composed of calcium carbonate. The formula of calcium carbonate is | CaCO3 |
| What is the name of NaH2PO4? | sodium dihydrogen phosphate |
| In the formula for ammonium nitrate, the number of nitrogen atoms is | 2 |
| How many iron atoms are in the formula for iron(III) oxide? | 2 |
| Which one of the following compounds does NOT obey the "octet rule"? | SCl6 |
| The number of electrons contained in several molecules and ions is shown below. Which of the following is most likely to be a free radical? | 13 |
| The valence shell electron pair repulsion theory (VSEPR) is used to | predict the three dimensional structure of molecules |
| If a central atom has a total of three electron sets and no lone pairs attached to it, the geometry about the central atom is | trigonal planar |
| The VSEPR theory is based on | the minimization of repulsion among valence electron pairs |
| Which of the following molecules is polar? | CH2Cl2 |
| Which of the following statements about molecules is correct? | A compound that contains only polar bonds can be nonpolar. |
| Which state of matter is characterized by having molecules far apart and moving randomly? | gas |
| The temperature at which a liquid becomes a solid is called the | melting point |
| The process by which a solid is converted to a gas is called | sublimation |
| Matter is more likely to exist in the ________ state as the pressure is increased. | solid |
| Temp which solid melts is melting pt of the solid. Melting pt is an ind of the IMF that hold the solid together. H20 melts at 0°C. Sucrose melts at 285. Ga, melts at 30°C. Which one ranks the IMF in these solids from the strongest to the weakest? | sucrose > Ga > water |
| List the disadvantage of using supercritical carbon dioxide | Special equipment is needed for the high temperature and high pressure. |
| Which process involves the removal of energy (heat)? | condensation |
| Which of the following compounds will have the highest melting point? | BaF2 |
| Methanol | can dissolve in water and will not conduct electricity |
| Which of the following properties are NOT a characteristic of ionic compounds? | They have low boiling points |
| For which of the following is hydrogen bonding NOT a factor? | CH4 |
| Liquid hydrogen is used as one part of the booster fuel in the space shuttle. What type of forces exist between hydrogen molecules in liquid hydrogen? | dispersion forces |
| Water is a liquid at room temperature while methane is a gas. Which statement compares the intermolecular forces in these molecules correctly? | The intermolecular forces in water are stronger than those in methane |
| When an ionic compound dissolves in water | the negative ends of water molecules surround the positive ions |
| Which of the following is NOT a postulate of the kinetic-molecular theory? | The molecules of a gas are strongly attracted to each other |
| The volume of one mole of krypton at STP is | 22.4 liters |
| The density of O2 gas at STP is | 1.43 g/L |
| For a given amount of gas at a constant temperature, the volume of gas varies inversely with its pressure is a statement of ________ Law. | Boyle's |
| A gas is enclosed in a cylinder fitted with a piston. The vol of the gas is 5.00 L at 0.500 atm pressure. The piston is moved to increase the volume to 3.00 L. Which of the following is a reasonable value for the pressure of the gas at the greater vol? | 0.833 atm |
| The statement that the volume of a fixed amount of a gas at a constant pressure is directly proportional to its absolute temperature is known as ________ Law. | Charles's |
| A balloon is inflated outdoors on a cold day in North Dakota at a temperature of -35°C to a volume of 3.0 L. The pressure remains constant. What is the volume of the balloon indoors at a temperature of 25°C? | 3.8 L |
| The pressure of a gas will increase when | the volume decreases |
| Use the ideal gas law to calculate the volume occupied by 0.400 mol of nitrogen gas at 3.00 atm pressure and at 27°C. R = 0.0821 L * atm/(K*mol). | 3.28 L |
| It requires more energy to melt one mole of an ionic compound than one mole of a molecular compound. T/F | True |
| A covalent bond is weaker than a hydrogen bond. T/F | False |
| The phrase "like dissolves like" means that a polar substance will dissolve readily in a polar solvent. T/F | True |
| The conditions for standard temperature and pressure (STP) are 1 atm pressure and 0°C. T/F | True |
| Temperatures must be converted to the Celsius temperature scale when Charles's Law is used. T/F | False |
| If the pressure of a gas rises, the gas molecules will strike the walls of its container more frequently. (Assume that the container has a definite shape and volume.) T/F | True |
| The ideal gas law can be used to determine a new volume for a gas when its temperature is changed. T/F | False |
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