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Chemistry

Exam 2/ chapters 4,6, and 11

TermDefinition
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
Created by: vtlove116