Biology - Chapter 4

Assignment #2 Chemistry Problems

The smallest functional unit of an element is a

Atom

An atom is said to be electrically neutral when it has equal numbers of protons and

electrons

How many electrons does a P(hosphorus) atom contain?

Atomic mass: 31

Atomic number: 15

15

What kind of bond results when electron pairs are shared between atoms?

covalent bond

What is meant by water being a "polar" molecule?

oxygen pulls electrons more toward itself than the hydrogens do

When the pH of a substance is 5, the substance is

Acidic

When the pH of a substance is 9, the substance is

Basic

When the pH of a substance is 7, it is

Neutral

An atom that has gained one or more electrons is called

anion

A double covalent chemical bond represents the sharing of how many electrons?

4

A substance with specific properties that cannot be broken down or converted into another substance is called a

Element

Calcium is element number 20 on the periodic table. Its atomic weight is 40.078.

How many protons does it have?

20

Calcium is element number 20 on the periodic table. Its atomic weight is 40.078.

How many neutrons does it have?

20

Calcium is element number 20 on the periodic table. Its atomic weight is 40.078.

How many electrons does it have?

20

Calcium is element number 20 on the periodic table. Its atomic weight is 40.078.

What is its atomic number?

20

Calcium is element number 20 on the periodic table. Its atomic weight is 40.078.

How many electrons are in its outer shell?

2

For an atom to achieve maximum stability, not seek to form bonds, and be chemically inert, what must occur?

Its outermost energy shell must be filled with electrons

In general, a substance that carries an electric charge can dissolve in water. Given this fact, which of the following would most likely NOT dissolve in water?

nonpolar molecules

Ionic bonds

are formed when 1 atom donates 1 or more electrons to another atom

Polar covalent bonds form when

electrons are shared unequally between atoms

Polar molecules

have an unequal distribution of electric charge

The difference between cohesion and adhesion is that

cohesion is the ability of like molecules to stick to one another while adhesion is the ability for molecules to stick to another surface

The specific heat of water is 10 times greater than that of iron. You place a metal pot full of water on the stove to heat it up. You touch the metal handle of the pot when the water is still only lukewarm. Which of the following BEST describes what happens?

You burn your finger and pull your hand away from the very hot handle.

Water molecules are cohesive because they

form hydrogen bonds

What is calcium abbreviated as?

Ca

What is meant by the statement that water has a high specific heat?

It can absorb a lot of energy without changing temperature

You drop a handful of salt into a glass of water. Which of the following BEST describes what is happening inside the glass at the molecular level?

The positively charged hydrogen ends of the water molecules are attracted to chloride ions