Bio Ch.2

The number of neutrons present in the nucleus of an average atom of any given element is best estimated by

subtracting the number of protons from the mass number.

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 H+

How does a strong acid differ from a weak acid?

A weak acid dissociates only partially in water.

Cola has a pH of 3.5. This means that it has an excess of ________ ions and would be called a(n) ________.

H+; acid

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

Hydrogen bonds are broken between neighboring water molecules.

All atoms of the same element have the same

atomic number

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+ ions from stomach acid.

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

Living organisms are able to maintain their internal body temperatures because the water in their cells resists changes in temperature.

Which of the following is not a compound?

O^2

Although Oregon and South Dakota are at similar latitudes, winters in Oregon are warmer and summers in Oregon are cooler. Which of the following might explain these differences between the climate of Oregon and the climate of South Dakota?

The Pacific Ocean makes Oregon temperatures more moderate.

Regarding atoms, identify which statement below is correct.

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

Which of these does not occur when a sodium atom transfers an electron to a chlorine atom?

There is a mutual sharing of the electrons between the sodium and chlorine atoms.

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

They all produce H+ ions 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 property of water causes sugar to dissolve in coffee?

Water is a good solvent.

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

A(n) ________ can be defined as a substance that prevents the pH of a solution from changing by either releasing or absorbing H+ in a solution.

buffer

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

compound

The pH scale is a mathematical indicator of the

concentration of H+ present in a solution.

Which of the following would not be a valuable use for radioactive isotopes?

damaging DNA of healthy cells

An atom's valence 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.

Which of the following is a property of acids?

have a pH reading above 7.0

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

iron

The atomic structure of water satisfies the octet rule by having

oxygen share electrons with two hydrogen atoms.