chapter 2 review (biology)

which of the following statements correctly defines 1 kilocalorie ?

1,000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C

One mole (mol) of glucose (molecular mass = 180 daltons) is ?

180 grams of glucose.

What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen?

2

the nucleus of a nitrogen atom contains 8 neutrons and 7 protons. which of the following is a correct statement concerning nitrogen?

the nitrogen atom has a mass number of 15 and an atomic number of 7

The chemical behavior of an atom depends primarily upon which of the following?

the number of electrons in the valence shell

the left-to-right position of an element in the first three rows of the periodic table indicates which of the following properties of the elements?

the number of electrons in the valence shell

which of the following properties is shared by elements in the same row of the periodic table ?

they have the same number of electron shells

An ionic bond is formed by

transfer of an electron from one atom to another.

One difference between carbon -12 (12 /6 C) and carbon -14 (14 /6 C) is that carbon -14 has ?

two more neutrons than carbon -12

What type of bonding or interaction is most likely to occur among a broad array of molecules with various physical properties (polar, nonpolar, hydrophilic, hydrophobic)?

van der Waals interactions

a covalent bond is likely to be polar when ?

one of the atoms sharing electrons is much more electronegative than the other atom

A covalent chemical bond is one in which

outer-shell electrons of two atoms are shared so as to occupy the outer electron shells of both atoms.

the attraction between the slight negative charge of one water molecule to the slight positive charge of another water molecule results in which of the following interactions ?

a hydrogen bond

unequal sharing of electrons between atoms will result in which of the following interactions

a polar covalent bond

Which of the following molecules contains the most polar covalent bond?

H2O

Which of the following are considered compounds?

H2O and CH4, but not O2

Why does ice float in liquid water?

Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the following molecules would be formed?

H—S—H

If a salamander clings to surfaces through hydrogen bonds, it would have the most difficulty clinging to which of the following surfaces?

a surface coated with a thin film of vinegar (acetic acid)

The atomic number of chlorine is 17. The atomic number of calcium is 20. What is the chemical formula for calcium chloride?

CaCl2

44) What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?

6

Which of the following effects is produced by the high surface tension of water?

A water strider can walk across the surface of a small pond.

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements about the atoms in ammonia (NH3) is correct?

Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

Which of the following takes place as an ice cube cools a drink?

Kinetic energy in the drink decreases.

The most stable interaction between magnesium (atomic number 12) and chlorine (atomic number 17) forms which of the following molecules?

MgCl2, in which atoms are joined by ionic bonds.

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following is true?

Molybdenum atoms can have between 50 and 58 neutrons.

In ammonium chloride salt (NH4Cl), the anion is a single chloride ion, (C1-). What is the cation of NH4Cl salt ?

NH4, with a charge of +1

which of the following correctly describes any reaction that has reached chemical equilibrium?

The rate of the forward reaction is equal to the rate of the reverse reaction.

which of the following properties is common among elements in the same column of the periodic table ?

They have the same number of electrons in their valence shell.

which four of the 92 naturally occurring elements make up approximately 96%of the mass of the human body ?

carbon, hydrogen, nitrogen, oxygen

Water molecules are able to form hydrogen bonds with ?

compounds that have polar covalent bonds.

Which bond or interaction would be most difficult to disrupt when compounds are put into water?

covalent bond

Which of the following are the strongest molecular interactions?

covalent bonds

how does the formation of covalent bonds differ from the formation of ionic bonds between two atoms ?

covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the transfer of electrons from one atom to another

4) Which of the following is primarily responsible for the unique chemical properties of each element?

each element has a unique number of protons

chemical equilibrium is described by which of the following statements ?

forward and reverse reactions continue with no effect on the concentration of the reactants and products

In an aqueous solution, water molecules associate with one another through which of the following?

hydrogen bonds

conversion of liquid water to water vapor requires breaking which of the following types of bonds ?

hydrogen bonds

trace elements are required by organisms in only minute quantities (less than 0.01% of mass). which of the following is a trace element that is required by humans and other vertebrates?

iodine

3) Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by all organisms?

iron

When two atoms are equally electronegative, they will interact to form

nonpolar covalent bonds.

Hydrophobic substances such as vegetable oil are?

nonpolar substances that repel water molecules.

Sulfur is in the same column of the periodic table as oxygen but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S will ?

not form hydrogen bonds with each other.

Two atoms that have the same mass number must have the same

number of protons + neutrons.

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

polar covalent bonds.

given only a mass number, one can deduce the number of__________in each atom of an element.

protons plus neutrons

A covalent bond is formed by ?

sharing of a pair of electrons between two atoms.