Chemistry- Exam 1
Alchemist of the Middle Ages believed that ________.
A substance can be transformed into gold by altering its basic qualities
How would you classify the following material? milk
A suspension
23) What does the following element description actually mean? 238 U 92
A uranium atom with 92 protons and 146 neutrons
The systematic names for water, ammonia, and methane are dihydrogen monoxide, H2O; trihydrogen nitride, NH3; and tetrahydrogen carbide, CH4. Why do most people, including chemists, prefer to use the common names for these compounds?
A) The common names are more widely known. B) The common names are shorter and easier to pronounce. C) These compounds are encountered frequently.
How might you separate a mixture of sand and salt?
A) heat the mixture until one of the components melts C) just add water
A post-1982 penny is made with zinc, but its density is actually greater than that of zinc because ________.
A) it is coated with a thin layer of copper, which is more dense than zinc C) it has more mass for the same volume
Which of the following is not a form of electromagnetic radiation? A) sound waves B) infrared C) X-rays D) gamma rays E) microwaves
A) sound waves
Which of the following would not be considered a physical property? A) temperature at which a material catches on fire B) hardness C) temperature at which a material melts D) color E) conductivity
A) temperature at which a material catches on fire
Which of the following is said to be quantized? A) the number of eggs in an egg carton B) the volume of air in a balloon C) the amount of water in a glass D) the amount of time in an hour E) none of the above
A) the number of eggs in an egg carton
Based on the Law of Mass Conservation, Lavoisier hypothesized that ________.
An element is made of a fundamental substance that cannot be broken down into anything else
Why do aerosol cans explode if heated?
An increase in temperature will increase the pressure inside the aerosol can. When the pressure inside the can exceeds the pressure limit of the can, it explodes.
18) Which of the following could best be represented by a physical model? A) rationality B) a cell C) ecosystem D) an atom E) both A and B
B) a cell
Which of the following is a pure substance? A) duct tape B) baking soda C) orange juice D) salt water E) cooking oil
Baking soda
The atomic symbol for cobalt is ________.
Co
Which experiences a greater effective nuclear charge, an electron in the outer shell of neon (atomic number 10) or an electron in the outer shell of sodium (atomic number 11)?
Neon because of less inner shell shielding
Isotopes of the same element have a different number of ________.
Neutrons
What prompted early scientists to propose that the ray of the cathode ray tube was actually a negatively charged particle?
The ray was attracted to positively charge electric plates.
What prompted early scientists to propose that the ray of the cathode ray tube was due to the cathode?
The ray was present regardless of gas, or even without a gas.
Some older cars vibrate loudly when driving at particular speeds. For example, at 65 mph the car may be most quiet, but at 60 mph the car rattles uncomfortably. How is this analogous to the quantized energy levels of an electron in an atom?
The vibrating car is analogous to one of the energy levels of the electron, which is the point at which the electron experiences resonance.
At a depth of about 10 meters the water pressure on you is equal to the pressure of 1 atmosphere. The total pressure on you is therefore 2 atmospheres1 atm from the water and a second atm from the air above the water. When the glass shown below is pushed down to a depth of around 10 meters in depth, what will be the level of the water on the inside of the glass?
The water level will have risen to about the halfway mark.
Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H2O, have similar properties?
No, compounds are uniquely different from the elements from which theyʹre made.
Oxygen, O2, is certainly good for you. Does it follow that if small amounts of oxygen are good for you then large amounts of oxygen would be especially good for you?
No. Breathing 100% oxygen for extended periods of time can be damaging to the body.
Should the periodic table be memorized? Why or why not?
No. The periodic table is a reference to be used, not memorized.
Rutherford assumed that the atomic nucleus was positively charged because ________.
Two of the above are reasonable answers
Does a shell have to contain electrons in order to exist?
Two of the above are reasonable answers.
Considering how small atoms are, what are the chances that at least one of the atoms exhaled in your first breath will be in your last breath?
Very probable because of how incredibly small atoms are
Which of the following is an example of a physical change?
Water boiling and being converted into steam
In what sense can you truthfully say that you are a part of every person around you?
We are continually exchanging our atoms.
Why canʹt we see atoms?
We see with light energy and the wavelength of light is larger than the atom and is not reflected.
What is the difference between mass and weight?
Weight is the observed effect of gravity on mass.
Classify the following as element, compound, or mixture, and justify your classifications: sodium chloride, stainless steel, sugar, aluminum, ice.
compound; mixture; compound element; compound
Your weight is always ________.
Not the same thing as your mass
A sample of iron weighs more after it rusts because ________.
Of the additional oxygen it contains
A TV screen looked at from a distance appears as a smooth continuous flow of images. Up close, however, we see this is an illusion. What really exists are a series of tiny dots (pixels). This is similar to a chemistʹs view of matter in that ________.
On the submicroscopic level, chemistʹs find that matter is made of extremely small particles, such as atoms and molecules.
Red colored Kool-Aid crystals are added to a still glass of hot water. The same amount of crystals are added to a second still glass filled with the same amount of cold water. With no stirring, which of the following would occur?
The glass of hot water will reach a uniform red color first since the higher kinetic energy provides for faster moving molecules to more quickly distribute the dye.
The density of air at 25°C and 1 atmosphere of pressure is about 1.18 g/L. What happens to the density of air as the temperature is increased? When the pressure is increased?
Temperature increase causes density to decrease; pressure increase causes density to increase
The oldest known elements in the periodic table are the ones ________.
That match their Latin names
Which chemical family is composed almost entirely of synthetic elements?
The actinides
Why are the atomic masses listed in the periodic table not whole numbers?
The atomic masses are average atomic masses.
What is the difference between a compound and a mixture?
The components of a mixture are not chemically bonded together.
What happens to the density of a filled water balloon as it is pulled to the bottom of the ocean?
The density of the filled water balloon increases since the balloon is compressed to a smaller volume.
Assuming temperature remains constant, what happens to the density of a gas as the gas is compressed into a smaller volume?
The density of the gas increases along with the decreasing volume.
An electron de-excites from the fourth quantum level to the third and then directly to the first. Two frequencies of light are emitted. How do their combined energies compare to the energy of the single frequency that would be emitted by de-excitation from the fourth level directly to the first level? Answer: The combined energies of the two frequencies emitted by the one electrons is ________.
equal to the energy of the single frequency
Which of the following does not describe mass?
how much space an object occupies
How would you describe the volume of the following object? the amount of water in a swimming pool
macroscopic
Would you use a physical model or a conceptual model to describe the following: the brain; the mind; the solar system; the beginning of the universe?
physical; conceptual; physical; conceptual
Which of the following elements will most likely be shiny and flexible?
rhodium (Rh)
What is the name of the following compound? NaF
sodium fluoride
27) Using the following generic atom description, choose the correct method for determining the number of neutrons. F X G
subtract G from F
What is the name of the following compound? SF3
sulfur trifluoride
How might the spectrum of an atom appear if its electrons were not restricted to particular energy levels?
A broad spectrum of all colors would be observed.
What is a physical change?
A change in which the form or appearance changes, but no new substances are formed.
What is a mixture?
A combination of two or more substances that are not chemically combined
Which of the following is generally true regarding the relationships of the density of an object and its massiveness?
A denser object is not necessarily always more massive.
A chemical change involves a change in ________.
How atoms are bonded
Which of the following statements does not describe a proton? A) It is a nucleon. B) It orbits around the nucleus of an atom. C) It has a positive charge equivalent but opposite of an electronʹs. D) It is much more massive than an electron. E) It is attracted to negatively charged electrical plates.
It orbits around the nucleus of an atom.
15) The element silicon has a melting point of 1,410°C and a boiling point of 2,355°C. It is a weak conductor of electricity, its density is 2.3 grams per cubic centimeter and it easily forms silicon dioxide when exposed to air. Which of the following is a chemical property of silicon?
Its ability to react with oxygen to form silicon dioxide
Neon, Ne, (number 10) has a relatively large effective nuclear charge, yet it cannot attract any additional electrons because ________.
Its outermost shell is already filled to capacity
Which of the following statements best describes electromagnetic radiation?
Light waves are oscillations of electric and magnetic fields.
Which of the following temperatures is not possible?
-200K
Nanotechnology looks at working with particles ________.
1 to 100 nanometers, the realm of individual atoms and molecules
Compared to microtechnology, nanotechnology focuses on a scale that is about ________.
1000 times smaller
Which temperature is the hottest?
100°C
Which of the following is not a measurement of volume?
5.5 milligrams
Which of the following is not a volume measurement?
5.5 milligrams
How many milliliters of air are there in a hole measuring 5 L?
5000 mL
If a neutral element has the following chemical notation, how many electrons does it have? carbon-13
6
Visible light has a frequency range between 7 × 1014 Hz and 4 × 1014 Hz. Which frequency of light would have the most energy?
7 × 1014 Hz
If a neutral element has the following chemical notation, how many electrons does it have? fluorine-19
9
If a neutral element has the following chemical symbol, how many electrons does it have? 235 U 92
92
How many joules are there in a candy bar containing 230,000 calories?
960,000 joules
Is aging primarily an example of a physical or chemical change?
Aging is an example of a chemical change involving the chemical reformation of our biomolecules.
32) Nanotechnology may play an important role in the development of ________. A) windfarms B) bullet proof clothing C) space elevators D) a storage medium for hydrogen fuel E) all of the above
All of the above
Nanotechnology and microtechnology are similar in that they both ________. A) are relatively new technologies C) have huge impacts on society B) are interdisciplinary D) all of the above
All of the above
How does a suspension differ from a solution?
Although a solution and suspension are both homogeneous mixtures, only the components of a suspension will separate by spinning the mixture in a centrifuge.
What does the following element description actually mean? 18 O 6
An oxygen atom with 6 protons and 12 neutrons
What is a halogen?
Any of the six nonmetallic elements that constitute Group 17 (Group VIIa) of the periodic table.
Which of the following elements is a gas at room temperature? A) lead (Pb) B) indium (In) C) argon (Ar) D) lithium (Li) E) cesium (Cs)
Argon (Ar)
How does Aristotle's model of matter explain why the air over a flame is always moist?
Aristotle' model of matter would explain. quite the opposite and predict the air above the flame would become dry
Alcohol wiped across a table top rapidly disappears. Which of the following is true?
As the alcohol evaporates it soaks up energy from the table top which is thus cooled.
A minimum temperature exists (absolute zero). Why does no known maximum temperature exist?
Assuming no limit on the relative speed of atoms and molecules, it follows that there is no maximum temperature.
Humidity is a measure of the amount of water vapor in the atmosphere. Why is humidity always very low inside your kitchen freezer?
At the cold temperatures of your kitchen freezer, water. molecules in the vapor phase are moving relatively slowly, which makes it easier for them to stick to inner surfaces within the freezer or to other water molecules
A supersonic airplane heats up considerably when traveling through the air at speeds greater than the speed of sound. As a result, the airplane during supersonic flight is longer than when it is at rest on the ground. Offer an explanation for this length change from a submicroscopic perspective.
Atmospheric air molecules hit the supersonic plane at great velocities causing the atoms of the planes metal skin to start moving faster.
25) Which of the following atoms is the smallest? A) Ga B) Br C) K D) As E) Ca
B) Br
40) Which of the following gases would diffuse the slowest through an extremely fine membrane? A) He B) F2 C) N2 D) O2 E) All of the above would diffuse at the same rate.
B) F2
Why do scuba divers exhale air when they ascend to the surface after a dive? A) The air bubbles which surround the diver as he/she exhales assists overall buoyancy making it easier for the diver to ascend. B) Exhaling of air decreases the volume of air in the lungs, thus making it easier for the lungs to adjust to the decrease in external pressure on the diver as the diver ascends. C) If the air in the lungs were not exhaled, the volume of air inside the lungs would expand as the diver ascended and could severely damage the lungs. D) Both B and C are true. E) None of the above are true.
Both B and C are true.
47) Which of the following elements is an alkali metal? A) cerium (Cr) B) argon (Ar) C) lithium (Li) D) lead (Pb) E) indium (In)
C) lithium (Li)
What is the name of the following compound? CO2
Carbon dioxide
Classify the following changes as physical or chemical. Wood burns to ashes; water begins to boil; grass grows; a rock is crushed to powder.
Chemical; physical; chemical; physical
Which of the following elements is a halogen?
Chlorine (Cl)
Half-frozen fruit punch is always sweeter than the same fruit punch completely melted because ________.
Crystallization is a purifying process
In the winter Vermonters make a tasty treat called ʺsugar on snowʺ in which they pour boiled-down maple syrup onto a scoop of clean fresh snow. As the syrup hits the snow it forms a delicious taffy. Which of the following changes are involved in the making of sugar on snow? A) As the maple syrup is boiled the sugar within the syrup begins to caramelize, which is an example of a chemical change. B) Boiling down the maple syrup involves the evaporation of water. C) The syrup warms the snow causing it to melt while the syrup becomes more viscous. D) All of the above changes are involved in the making of sugar on snow.
D) All of the above changes are involved in the making of sugar on snow.
Which of the following best describes a conceptual model of an atom? A) a model that illustrates the physical structure of the atom B) a model that represents the shape of the nucleus and the location of the electrons C) a description of the location of the neutrons and protons in an atom D) a model that illustrates the tendency of an atom to undergo radioactive decay and the products it produces E) none of the above
D) a model that illustrates the tendency of an atom to undergo radioactive decay and the products it produces
Dmitri Mendeleev ________. A) helped in the discovery of missing elements by predicting their behavior B) predicted the existence of elements not yet discovered C) developed the basis of our modern periodic table D) all of the above
D) all of the above
The phase in which atoms and molecules no longer move is ________. A) the liquid phase B) the solid phase C) the gas phase D) none of the above
D) none of the above
With increasing temperature the density of air ________.
Depends also on pressure
The following statement describes which subatomic particle best? It is a nucleon. A) an electron B) a proton C) a neutron D) A and B E) B and C
E) B and C
21) From which of the following atoms would removing an electron be the most difficult? A) Rb B) Cd C) I D) Sr E) Xe
E) Xe
Which of the following is a metal? A) selenium (atomic no. = 34) B) xenon (atomic no. = 54) C) helium (atomic no. = 2) D) sulfur (atomic no. = 16) E) titanium (atomic no. = 22)
E) titanium (atomic no. = 22)
What are metalloids?
Elements that have some properties like metals and some like nonmetals
Gas particles travel at speeds of up to 500 meters per second. Why, then, does it take so long for gas molecules to travel the length of a room?
Gas particles bump into each other as well as other particles in the air.
What determines the direction of heat flow?
Heat always flows from a higher-temperature substance into a lower-temperature substance.
Which of the following would best describe heat?
Heat is energy that moves from high to low temperature objects
When water freezes, it expands. What does this say about the density of ice compared with the density of water?
Ice is less dense than water because it has more volume for the same mass.
If you remove two protons and two neutrons from a gold atom (Au), what new element is formed?
Ir2-
List the following elements in order of increasing ionization energy: Tin, Sn; Lead, Pb; Phosphorus, P; Arsenic, As.
Pb < Sn < As < P
17) What is the difference between radiation and electromagnetic radiation?
Radiation is from decay of nuclei while electromagnetic radiation is any form of light.
36) Which of these is not a metal? A) gallium (atomic no. = 31) B) selenium (atomic no. = 34) C) vanadium (atomic no. = 23) D) lithium (atomic no. = 3) E) potassium (atomic no. = 19
Selenium (atomic no. = 34)
If you remove two protons and two electrons from a sulfur atom (S), what new element is formed?
Si
If you eat metallic sodium or inhale chlorine gas, you stand a strong chance of dying. Let these two elements react with each other, however, and you can safely sprinkle the compound on your popcorn for better taste. What is going on?
Sodium chloride has nothing in common with the properties of the elements sodium and chlorine.
An electron in the outermost shell of which group 1 element experiences the greatest effective nuclear charge?
Sodium, Na
An element has two different isotopes: one that weighs 65 amu and another that weighs 67 amu. If the average atomic mass of all the isotopes is 66.5 amu, what can be said about the relative abundance of the isotopes?
The isotope with the mass of 67 is more abundant than the isotope with the mass of 65.
Daltonʹs atomic model gained credibility because ________.
The model worked to explain much about known chemical reactions
Why isnʹt dirt listed in the periodic table?
The periodic table lists only elements made of one kind of material. Dirt is a mixture of elements and compounds.
What happens to the properties of elements across any period of the periodic table?
The properties of the elements gradually change across any period of the periodic table.
Place a card over the open top of a glass filled to the brim with water, and then invert it, as is shown below. Why does the card stay in place? How about when the glass is held sideways?
The weight of the air pushing against the outer surface of the card is much greater than the weight of the water pushing against the inner surface of the card, whether inverted or held sideways.
When you suck through a soda straw into a drink as shown in the illustration below, what causes the drink to rise into your mouth: the muscles of your lungs and cheeks or the weight of the atmosphere?
The weight of the atmosphere
Why canʹt the elements of a compound be separated from one another by physical means?
Their atoms are too tightly bound to one another.
What do the electron configurations for all the group 18 noble gases have in common?
Their outermost occupied shells are filled to capacity.
If you drop a hot rock into a pail of water, the temperature of the rock and the water change until the two are equal. The rock cools and the water warms. Does this hold true if the hot rock is dropped into the Atlantic Ocean?
Yes, because heat will continue to flow until they have the same temperature
How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope?
You would see one line of emitted light, but it would be different for each element.
Which has more atoms: a 1-gram sample of carbon-12 or a 1-gram sample of carbon-13?
a 1-gram sample of carbon-12
Which of the following best describes a liquid?
a constant volume but its shape is not defined
Which statement best describes a compound?
a material that is made up of a combination of atoms bonded together
Which of the following is a mixture?
air
Rank the following by relative frequency from highest to lowest:
gamma rays, blue light, red light, radio waves
Which of the following units of measurement could be used to describe density?
kilograms per liter