PHS exam 3

Each atom of an electron-dot structure must have eight electrons. Select one: True False

False

Hydrogen atoms are often the central atom of an electron-dot structure. Select one: True False

False

Classify these molecules as polar or nonpolar. H2 HCI CBr4 BCI3 CH3NH3

H2 None HCI Polar CBr4 polar BCI3 Polar CH3NH3 Polar

For a neutral molecule, the number of electrons in the electron-dot structure is the sum of the valence electrons for the atoms. Select one: True False

True

For a neutral molecule, the number of electrons in the electron-dot structure is the sum of the valence electrons for the atoms. Select one: True False

True

Classify these elements as solids, liquids or gases. Select one: a. Ag, S and Si are solids, Hg is a liquid and Ne is a gas. b. Ne and S are gases, Si and Hg are liquids, and Ag is a solid. c. Ag, S and Si are solids, Hg is a gas and Ne is a liquid. d. Liquids are Hg, Ne and Si; S is a gas, Ag is a solid.

a. Ag, S and Si are solids, Hg is a liquid and Ne is a gas.

Select the diagrams that show the absorption of energy by electrons to produce an atom with an electron in the excited state. Check all that apply. a. B, D, E b. E c. B d. A, C e. A f. C g. D

a. B, D, E

Electron-dot structures are needed to help us understand what kinds of chemical bonds? Select one: a. Both ionic and covalent bonds b. Covalent bonds c. Metallic bonds d. Ionic bonds

a. Both ionic and covalent bonds

Which of these compounds has the most atoms? (a) C12H22O12, (b) DNA, (c) Pb(C2H3O2)2. Select one: a. C12H22O12 b. DNA c. Pb(C2H3O2)2

a. C12H22O12

Are atoms made of molecules or are molecules made of atoms? Select one: a. Molecules are always made of atoms. b. Atoms are always made of molecules. c. Molecules are sometimes made of atoms. d. Atoms are sometimes made of molecules.

a. Molecules are always made of atoms.

Think about the chemical symbol for sodium. What is the Latin name for sodium? Select one: a. Natrium b. Stibium c. Plumbium d. Sodactium

a. Natrium

What is the definition of chemistry? Select one: a. The study of matter and the transformations it can undergo b. The applied science of matter and energy c. The branch of science arising from the study of the physics of the atom d. The study of chemicals, which are compounds made of atoms and molecules

a. The study of matter and the transformations it can undergo

Which choice shows several common transition metals? Select one: a. Tungsten, platinum, and iron b. Actinium, plutonium, and uranium c. Gallium, lead, and indium d. Sodium, potassium, and rubidium

a. Tungsten, platinum, and iron

Isotopes are identified by their _______ by scientists. Select one: a. atomic mass number b. atomic mass c. fraction of abundance d. atomic number

a. atomic mass number

Classify each of the changes as a physical change or a chemical change: sodium and chlorine atoms bonding to make salt (sodium chloride) Select one: a. chemical change b. physical change

a. chemical change

What happens to the atomic size as we move from left to right across a period of the periodic table? Select one: a. generally decreases. b. changes randomly with no general trend. c. does not change. d. generally increases.

a. generally decreases.

What happens to the atomic size (radius) as we move from top to bottom down a group of the periodic table? Select one: a. generally increases. b. changes randomly with no general trend. c. does not change. d. generally decreases.

a. generally increases.

This is an image of gallium and arsenic atoms obtained with a scanning probe microscope. Are gallium atoms really red and arsenic atoms green? Select one: a. no b. yes

a. no

Classify each of the changes as a physical change or a chemical change: a phase change like water freezing to ice. Select one: a. physical change b. chemical change

a. physical change

How fast does an electron move within an atom? Select one: a. About 90% the maximum Fermi velocity b. About 2 million m/s c. at about the speed of light d. About 1000 m/s

b. About 2 million m/s

Oxygen, O2, has a boiling point of 90 K (-183°C), and nitrogen, N2, has a boiling point of 77 K (-196°C). Which is a liquid and which is a gas at 80 K (-193°C)? Select one: a. Oxygen is a gas, nitrogen is a liquid at 80 K. b. Nitrogen is a gas, oxygen is a liquid at 80 K.

b. Nitrogen is a gas, oxygen is a liquid at 80 K.

What is an atom with great electronegativity able to do? Select one: a. Cancel dipoles b. Pull strongly on bonding electrons c. Form nonpolar covalent bonds d.Push electrons away from it

b. Pull strongly on bonding electrons

What type of force gives rise to an ionic bond? Hint: This force is exerted by both electrons and protons. Select one: a. The nuclear force b. The electric force c. An equal and opposite force d. The magnetic force

b. The electric force

The atoms that make your body _______. Select one: a. were created in the womb of your mother. b. are made in the cores of the stars c. were created from geological processes d. are made from the food you eat

b. are made in the cores of the stars

What is the name of the covalent compound CCl4? (The 4 should be a superscript but Moodle isn't going for it right now). Select one: a. tetracarbochloride b. carbon tetrachloride c. carbonochloride d. 4-chloro-1 carbonide

b. carbon tetrachloride

An example of a chemical change is the _______. Select one: a. mixing of sugar in water b. growth of a tree c. sublimation of carbon dioxide d. melting of ice

b. growth of a tree

Are most elements metallic, nonmetallic, metalloid, or not yet confirmed? Select one: a. nonmetallic b. metallic c. not yet confirmed d. metalloid

b. metallic

The fundamental unit of most covalent compounds is the _______. Select one: a. electron b. molecule c. ion d. atom

b. molecule

An electron, when farther from the nucleus, has _______. Select one: a. a higher frequency b. more potential energy c. greater electric charge d. less mass

b. more potential energy

What did Robert Brown see under the microscope? Select one: a. electromagnetic particles b. specks of dust moving around c. electrons oscillating d. atoms moving around

b. specks of dust moving around

What changes during a chemical reaction? Select one: a. the smell of a substance b. the arrangement of atomic bonds c. the density of a substance d. the color of a substance

b. the arrangement of atomic bonds

Identify where the elements would appear relative to one another in the periodic table. Select one: a. Ag, Hg on the right side. S and Ne on the left side. Si in between. b. All these elements would go in the same column. c. Ag, Hg on the left side. S and Ne on the right side. Si in between. d. Si and S on the left. Ne on the right. Ag and Hg in between the two.

c. Ag, Hg on the left side. S and Ne on the right side. Si in between.

Use the diagram of a neutral atom shown for reference. (The diagram of an atom given here is not drawn to scale. The nucleus of the atom is very small compared to the overall size of the atom. If an atom were the size of a football stadium, the nucleus would be about the size of a marble.) Which particle (A, B, or C) is the proton? Select one: a. C b. A c. B

c. B

What is the difference between basic research and applied research? Select one: a. Basic research studies alkaline compounds; applied research studies acids. b. Basic research studies mathematics; applied research studies technology. c. Basic research looks into the foundations of knowledge; applied research develops applications. d. Applied research looks into the foundations of knowledge; basic research develops applications.

c. Basic research looks into the foundations of knowledge; applied research develops applications.

Why do you NOT need to memorize the type of ion each atom tends to form? Select one: a. Because this is more science than the non-science major needs to know b. Because the type of ion an atom forms depends on the environmental conditions. c. Because this information is spelled out in the periodic table d. Because this information is readily available on the Internet

c. Because this information is spelled out in the periodic table

Which is an example of what an accurate conceptual model is able to predict? Select one: a. The support load capacity of a bridge b. The volume of air within a nuclear submarine c. Landfall of a hurricane d. The outcome of a single toss of a coin

c. Landfall of a hurricane

Name two physical properties of metals. Select one: a. Metals dissolve in water. b. Metals sink in water and they rust. c. Metals can be drawn into wires and are opaque. d. Metals are transparent and they conduct electricity.

c. Metals can be drawn into wires and are opaque

Use these properties to classify the substances as metals, metalloids, or nonmetals. The metalloids are: Select one: a. S, Ne b. Ag, Hg c. Si d. Ag, Hg, Si

c. Si

What happens to the atoms within molecules undergoing a chemical reaction? Select one: a. The atoms split in half. b. The atoms lose electrons. c. The atoms change partners. d. The atoms get really hot.

c. The atoms change partners.

How do we account for the great variety of substances in the world? Select one: a. The Earth is 4.5 billion years old. b. Atoms are incredibly small. c. There are many possible combinations of naturally occurring atoms. d. Most of these substances are organic compounds.

c. There are many possible combinations of naturally occurring atoms.

The subscripts within a chemical formula indicate the _______. Select one: a. polarity of the molecule b. number of protons within each atom c. charges on individual ions

c. charges on individual ions

Is a biological cell macroscopic, microscopic, or submicroscopic? Select one: a. A biological cell is both macroscopic and submicroscopic. b. macroscopic c. microscopic d. submicroscopic

c. microscopic

What is the chemical name for a compound with the formula Ba3N2? Select one: a. dinitro tribarimide b. nitro barimide c. tribarium dinitride d. barium nitrate

c. tribarium dinitride

Tutorial: What is the molecular formula for ammonium nitrate? Express your answer as a chemical formula. Select one: a. 2NH2NO b.NHNO c.NH4NO3

c.NH4NO3

What holds the positively charged metal ions together within a metallic bond? Select one: a. Ionic dipoles b. A fluid of positively charged protons c. Conductive energy d. A fluid of negatively charged electrons

d. A fluid of negatively charged electrons

Use these properties to classify the substances as metals, metalloids, or nonmetals. The metals are: Select one: a. Si, S, and Ne b. Ag, Hg, S, Ne c. Si d. Ag, Hg

d. Ag, Hg

Which of these has the largest diameter? a. Oxygen b. Flourine c. Carbon d. Beryllium

d. Beryllium

Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table. Why? Select one: a. H is a solid metal at room temperature so it goes on the left. b. They are randomly located c. He is halogen and belongs with those elements in group 18. d. Helium is placed over to the far right-hand side of the periodic table in group 18 because it has physical and chemical properties most similar to those of the other elements of group 18.

d. Helium is placed over to the far right-hand side of the periodic table in group 18 because it has physical and chemical properties most similar to those of the other elements of group 18.

How can you tell whether an atom within a compound takes on a positive or negative charge? Select one: a. Use an electroscope. b. Test to see if the compound attracts or repels a thin stream of water. c. See how crystals of the compound respond to a magnetic field. d. Locate the position of the atom in the periodic table.

d. Locate the position of the atom in the periodic table.

Which has the strongest dipole? Select one: a. Argon, Ar b. Oxygen, O2 c. Water, H2O d. Sodium chloride, NaCl

d. Sodium chloride, NaCl

Is it possible for the electrons of an atom or nonpolar molecule to be bunched to one side? Select one: a. No, because electrons repel each other b. Yes, because it minimizes the volume c. No, because of the central-oriented pull of the nucleus d. Yes, because electrons move randomly

d. Yes, because electrons move randomly

Is there a limit to the number of electrons that can occupy a single shell? Select one: a. Yes, there is a limit and it is because the electrons are too large and positively charged b. No, an unlimited number can occupy a shell. c. No, the number that can fit is unpredictable so science can't put a limit on it. d. Yes, there is limit

d. Yes, there is limit

A molecule forms an ion by either gaining or losing _______. Select one: a. mass b. a neutron c. a hydrogen ion d. an electron

d. an electron

What is the name of the covalent compound N2O5? (The 2 and 5 should be a superscripts but Moodle isn't going for it right now). Select one: a. pentoxide dinitrogen b. binitrogen-5-oxide c. dinitrocinqoxide d. dinitrogen pentoxide

d. dinitrogen pentoxide

An example of a physical change is the _______. Select one: a. growing of grass b. combustion of gasoline c. frying of an egg d. formation of a cloud

d. formation of a cloud

The elements fluorine, chlorine, and bromine are also known as _______. Select one: a. alkali metals b. noble gases c. chalcogens d. halogens

d. halogens

A unit or "particle" of light is the _______. Select one: a. muon b. pion c. electron d. photon

d. photon

The name of the compound with the formula of K2O is _______. Select one: a. dikryptonite oxide b. kay-too-oh c. oxygen potasside d. potassium oxide

d. potassium oxide

Dipoles cancel each other when _______. Select one: a. they face the same direction b. viewed from a macroscopic point of view c. the temperature is absolute zero d. they are equal and opposite

d. they are equal and opposite

Classify each of the properties as a physical property blank or a chemical property blank

melting point of sugar; smell of ginger

Classify these properties by whether you would have to perform a chemical reaction blank to test that property or if no chemical reaction is needed to test the property blank .

reactivity; flammability

Classify each of the changes as a physical change blank or a chemical change blank

slicing mango; tearing aluminum foil