CH 2 TCQ "A Chemical View of Life"

The pH of pure water is ______ because ___________________________.

7.0; water dissociates an equal number of H+ ions and OH-

An element has an atomic number of 78. The number of protons and electrons in a neutral atom of the element are

78 protons and 78 electrons

The type of bond that would form from the transfer of an electron from one atom to another, such as Na to Cl to complete the octet.

ionic

Which of the following is not one of the most common elements in living things?

iron

What type of bond allows water molecules to interact with one another?

hydrogen

An atom that has an electrical charge is called a(n)

ion

Which of the following explains the events occurring when water boils?

Hydrogen bonds are broken between neighbor water molecules.

Which of the following is NOT a property of water?

It is denser when frozen than when liquid.

Baking soda is sometimes used as an antacid. The chemical name for baking soda is Sodium Bicarbonate. What is the bicarbonate doing to help with stomach upset?

It is serving as a buffer to take up excess H+ ion from stomach acid.

Which of the following would be an example of the value of water's heat capacity?

Living organisms are better able to maintain their internal body temperature because the temperature of their environment changes very slowly.

What property of water causes sugar to dissolve in coffee?

Water is a good solvent.

Regarding atoms, identify which statement below is correct.

The number and arrangement of electrons in an atom governs its chemical activity.

What do lemons, tomatoes, and coffee all have in common chemically?

They all produce (H+) in solution, making them acids.

In what ways are radioactive isotopes potentially harmful?

Unmonitored release into the environment can make changes in a cell's DNA.

Of the following examples which best demonstrates the property of water cohesion?

Water can move up a 100 foot pine tree from the roots to the leaves.

Which property of water would help to account for how an individual who is exercising and producing excessive heat can maintain a constant body temperature?

Water has high heat capacity.

Which one of the following is the smallest unit of matter that has all the properties of an element?

atom

Isotopes of an atom differ in their

atomic mass

All atoms of the same element have the same

atomic number

Bases can

both take up hydrogen ions and release hydroxide ions.

Glucose, C6H12O6, is best described as a(n)

compound

An atom's outermost electron shell

determines its chemical reactivity

A covalent bond occurs when

electrons are shared between two atoms to complete their octets

An atom with a neutral charge has

equal numbers of protons and electrons

Engineers design city sidewalks using blocks of concrete separated by a small gap to prevent them from cracking. What property of water is being taken into account for this design? Water

is less dense when it is frozen

Isotopes of an element differ in their

neutron number

Elements differ from each other in their

physical properties and atomic number.

In the reaction 6CO2 + 6H2O C6H12O6 + 6O2 carbon dioxide is one of the

reactants

Sulfur has an atomic number of 16. What would be the valence number of this element?

six

Some insects can stride on the surface of water because water

surface tension

After drinking a great deal of coffee (pH 5), a human's blood buffering system would need to ______________ as the coffee was digested to lower the level of acid present in the blood stream.

take up OH-

The pH scale is a mathematical indicator of

the concentration of H+ present in a solution

Students were studying properties of water. One student placed a cup containing 80 mL of water in a freezer. Another student placed an identical cup containing 40 mL of water in the same freezer. Which of the following will be the same for both cups of water?

the temperature at which the water freezes

Which of these is a property of isotopes that make it useful in cell biology?

they behave the same chemically

Why do cells need buffering agents?

to minimize the changes in pH of their internal environment

A water molecule is polar because of

unequal sharing of electrons