chapter 2 :))))))))))))))))0

sharing of electron pairs between atoms

covalent

How many electrons would be expected in the outermost electron shell of an atom with atomic number 12? How many electrons would be expected in the outermost electron shell of an atom with atomic number 12? -2 -6 -1 -8 -4

-2

Oxygen has an atomic number of 8 and a mass number of 16. Thus, the atomic mass of an oxygen atom is

16 daltons

What is the maximum number of electrons in a 2p orbital of an atom? What is the maximum number of electrons in a 2p orbital of an atom? -1 -2 -3 -4 - 5

2

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)? Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)? -Each hydrogen atom has a partial positive charge. -The nitrogen atom has a partial positive charge. -The nitrogen atom has a strong positive charge. -There are covalent bonds between the hydrogen atoms. -Each hydrogen atom has a slight negative charge.

A

Which of the following is a trace element required by most living organisms? (Concept 2.1) Which of the following is a trace element required by most living organisms? (Concept 2.1) - magnesium -oxygen -hydrogen -carbon - nitrogen

A

Which of the following statements is false? Which of the following statements is false? -Protons and electrons are electrically charged particles. Protons have one unit of negative charge, and electrons have one unit of positive charge. -An atom is the smallest unit of an element that still retains the properties of the element. -Atoms of the various elements differ in their number of subatomic particles. -All atoms of a particular element have the same number of protons in their nuclei. -The neutrons and protons present in the nucleus of an atom are almost identical in mass; each has a mass of about 1 dalton.

A

From its atomic number of 15, it is possible to predict that the uncharged phosphorus atom has From its atomic number of 15, it is possible to predict that the uncharged phosphorus atom has -15 electrons. -15 protons and 15 electrons. -15 neutrons. -8 electrons in its outermost electron shell. -15 protons

B

What results from an unequal sharing of electrons between atoms? What results from an unequal sharing of electrons between atoms? - a nonpolar covalent bond -a polar covalent bond -an ionic bond -a hydrogen bond -a hydrophobic interaction

B

n ammonium chloride salt (NH4Cl) the anion is a single chloride ion, Cl-. What is the cation of NH4Cl? In ammonium chloride salt (NH4Cl) the anion is a single chloride ion, Cl-. What is the cation of NH4Cl? -NH4 with a charge of +1 -NH4 with a charge of +4 -H2 with a charge of +4 -H, with a charge of +1 -N, with a charge of +3

B

What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen? What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen? -1 -2 -3 -4 - 6

B.

3H is a radioactive isotope of hydrogen. One difference between hydrogen-1 ( 11H) and hydrogen-3 ( 31H ) is that hydrogen-3 has is a radioactive isotope of hydrogen. One difference between hydrogen-1 ( ) and hydrogen-3 ( ) is that hydrogen-3 has -one more electron and one more neutron than hydrogen-1. -one more neutron and one more proton than hydrogen-1. -two more neutrons than hydrogen-1. -two more protons than hydrogen-1. -one more proton and one more electron than hydrogen-1.

C

Which of the following describes any reaction that has reached chemical equilibrium? Which of the following describes any reaction that has reached chemical equilibrium? -All of the reactants have been converted to the products of the reaction. -All of the products have been converted to the reactants of the reaction. -Both the forward and the reverse reactions have stopped with no net effect on the concentration of the reactants and the products. -The rate of the forward reaction is equal to the rate of the reverse reaction. -The concentration of the reactants equals the concentration of the products

C

Which of the following would be regarded as compounds? Which of the following would be regarded as compounds? -O2 -H2 -H2O and CH4, but not H2 and O2 -H2O -CH4

C

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed? If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed? -S - H H | -H - S - H | H -H - S - H -H = S = H -H - S - H | H

C.

A molecule of carbon dioxide (CO2) is formed when one atom of carbon (atomic number 6) is covalently bonded with two atoms of oxygen (atomic number 8). What is the total number of electrons that must be shared between the carbon atom and the oxygen atoms in order to complete the outer electron shell of all three atoms? A molecule of carbon dioxide (CO2) is formed when one atom of carbon (atomic number 6) is covalently bonded with two atoms of oxygen (atomic number 8). What is the total number of electrons that must be shared between the carbon atom and the oxygen atoms in order to complete the outer electron shell of all three atoms? -2 -4 -6 -8 -10

D

How an atom chemically behaves when it comes into contact with other atoms is determined by its _____. (Concept 2.2) How an atom chemically behaves when it comes into contact with other atoms is determined by its _____. (Concept 2.2) -protons -neutrons -size; smaller things are chemically more reactive -electron configuration -nucleus

D

The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen? -The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen? -The nitrogen atom has a mass number of approximately 14 daltons and an atomic mass of 7. -The nitrogen atom has a mass number of approximately 7 daltons and an atomic mass of 14. -The nitrogen atom has a mass number of 14 and an atomic mass of 7 grams. -The nitrogen atom has a mass number of 7 grams and an atomic number of 14. -The nitrogen atom has a mass number of 14 and an atomic mass of approximately 14 daltons.

D

Which of the following best describes the relationship between the atoms described below? Atom 1 Atom 2 3115P 3215P Which of the following best describes the relationship between the atoms described below? Atom 1 Atom 2 -They are both phosphorus cations. -They are both isotopes of phosphorus. -They contain 31 and 32 electrons, respectively. -They contain 31 and 32 protons, respectively. -They are both phosphorus anions.

D

The atomic number of neon is 10. Therefore, which of the following is correct about an atom of neon? The atomic number of neon is 10. Therefore, which of the following is correct about an atom of neon? -It has 8 electrons in its outer electron shell. -It is inert. -It has an atomic mass of 10 daltons. -It has 8 electrons in its outer electron shell and it is inert. -All of the choices are correct.

D.

Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that -the atom would become a negatively charged ion, or anion. -an electron may move to an electron shell closer to the nucleus. -the atom would become a positively charged ion, or cation. -the atom may become a radioactive isotope. - an electron may move to an electron shell farther out from the nucleus

D. an electron may move to an electron shell farther out from the nucleus

A covalent bond is likely to be polar when A covalent bond is likely to be polar when it is between two atoms that are both very strong electron acceptors. the two atoms sharing electrons are of the same element. the two atoms sharing electrons are different elements. the two atoms sharing electrons are equally electronegative. one of the atoms sharing electrons is much more electronegative than the other atom.

E

A group of molecular biologists is trying to synthesize a new artificial compound to mimic the effects of a known hormone that influences sexual behavior. They have turned to you for advice. Which of the following compounds is most likely to mimic the effects of the hormone? A group of molecular biologists is trying to synthesize a new artificial compound to mimic the effects of a known hormone that influences sexual behavior. They have turned to you for advice. Which of the following compounds is most likely to mimic the effects of the hormone? -a compound with the same number of hydrogen and nitrogen atoms as the hormone -a compound with the same number of orbital electrons as the hormone -a compound with the same molecular mass (measured in daltons) as the hormone -a compound with the same number of carbon atoms as the hormone -a compound with the same three-dimensional shape as part of the hormone

E

A van der Waals interaction is the weak attraction between -a polar molecule and a nearby nonpolar molecule. -a polar molecule and a nearby molecule that is also polar. -a nonpolar molecule and a nearby molecule that is also nonpolar. -the electrons of one molecule and the electrons of a nearby molecule. -the nucleus of one molecule and the electrons of a nearby molecule.

E

Changing the number of _____ would change an atom into an atom of a different element. (Concept 2.2) -neutrons in an atom -bonds formed by an atom -electrons circling the nucleus of an atom -particles in the nucleus of an atom -protons in an atom

E

The atomic number of each atom is given to the left of each of the elements below. Which of the atoms has the same valence as carbon (126C) The atomic number of each atom is given to the left of each of the elements below. Which of the atoms has the same valence as carbon () -7nitrogen -9flourine -10neon -12magnesium -14silicon

E

The hybrid orbitals in a molecule of methane are oriented The hybrid orbitals in a molecule of methane are oriented -toward the corners of a triangle centered on the carbon atom. -toward the edges of an oval centered on the carbon atom. -toward the corners of a cube centered on the carbon atom. -toward the corners of a rectangle centered on the carbon atom. -toward the corners of a tetrahedron centered on the carbon atom

E

Which of the following best describes chemical equilibrium? Which of the following best describes chemical equilibrium? -Concentrations of products are higher than the concentrations of the reactants. -Reactions stop only when all reactants have been converted to products. -There are equal concentrations of reactants and products, and the reactions have stopped. -Forward and reverse reactions have stopped so that the concentration of the reactants equals the concentration of the products. -Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

E

Which of the following holds atoms together in a biological molecule? (Concept 2.3) Which of the following holds atoms together in a biological molecule? (Concept 2.3) - Nonpolar covalent bonding. -Van der Waals interactions -Hydrogen bonding. -Polar covalent bonding -All of the above

E

Which of the following is not considered to be a weak molecular interaction? Which of the following is not considered to be a weak molecular interaction? -a hydrogen bond -a van der Waals interaction -an ionic bond in the presence of water -a covalent bond and a van der Waals interaction -a covalent bond

E

Which of the following molecules contains the strongest polar covalent bond? Which of the following molecules contains the strongest polar covalent bond? -CH4 -CO2 -O2 -H2 - H2O

E

A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____. (Concept 2.1) - compound -element -isotope -molecule -proton

b

About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter?

carbon, hydrogen, nitrogen, oxygen

Which of the following explains most specifically the attraction of water molecules to one another? Which of the following explains most specifically the attraction of water molecules to one another? -hydrophobic interaction -hydrogen bond -nonpolar covalent bond -polar covalent bond -ionic bond

hydrogen bond

chemically unreactive

inert

the complete transfer of valence electron(s) between atoms

ionic bond

Different atomic forms of an element contain the same number of protons but a different number of neutrons. What are these different atomic forms called?

isotopes

The mass number of an element can be easily approximated by adding together the number of __________ in an atom of that element

protons and electrons