chapter 2

Question 1

Define the term element

Answer 1

Substances that can be broken down chemically

Elements are pure substances made of only one type of atom.

Question 2

Define the term atom

Answer 2

Smallest component of an element

Atoms are the basic building blocks of matter.

Question 3

Name the three principal subatomic components of an atom

Answer 3

• Proton: positive charge, inside nucleus
• Neutron: neutral charge, inside nucleus
• Electron: negative charge, outside nucleus

Question 4

Define atomic mass

Answer 4

Mass determined by # of protons and # of neutrons

Atomic mass is usually expressed in atomic mass units (amu).

Question 5

Define atomic number

Answer 5

Number used to identify atom, usually equals # of protons

The atomic number determines the element’s position in the periodic table.

Question 6

Define isotopes

Answer 6

Atoms with the same number of protons, different number of neutrons

Isotopes can vary in stability and may be radioactive.

Question 7

True or False: Isotopes that are not stable are considered radioactive.

Answer 7

True

Question 8

What are the most common elements found in the human body?

Answer 8

• Carbon
• Hydrogen
• Oxygen
• Nitrogen
• Phosphorus
• Sulfur

Question 9

Fill in the blank: An atom is stable (_______) if it has a full outer shell.

Answer 9

inert

Question 10

Fill in the blank: An atom is unstable (_______) if it interacts to fill other shells.

Answer 10

reactive

Question 11

Define the term ion

Answer 11

Atoms with a negative or positive charge

Ions are formed by the loss or gain of electrons.

Question 12

How do negatively charged ions form?

Answer 12

By gaining electrons

Question 13

How do positively charged ions form?

Answer 13

By losing electrons

Question 14

Explain ionic bonding

Answer 14

Electrons transferring between atoms (opposite attraction)

Ionic bonds typically form between metals and nonmetals.

Question 15

Explain covalent bonding

Answer 15

Electrons are shared between atoms

Covalent bonds can be polar or non-polar.

Question 16

Define non-polar covalent bonds

Answer 16

Equal sharing of electrons

Question 17

Define polar covalent bonds

Answer 17

Unequal sharing of electrons

Polar bonds result in partial positive and negative charges.

Question 18

What is a hydrogen bond?

Answer 18

Interaction between molecules based on polarity

A hydrogen bond occurs when a positively charged hydrogen atom interacts with a partial negative charge.

Question 19

Describe cohesion in water

Answer 19

Stickiness, water’s ability to interact with itself

Cohesion allows water to move up the roots of trees.

Question 20

Describe adhesion in water

Answer 20

Water’s ability to interact with other molecules

Adhesion allows water to move through capillary action against gravity.

Question 21

Define pH

Answer 21

Scale used to measure base or acidity of any liquid solution

pH values range from 0 to 14, with 7 being neutral.

Question 22

What ions influence the pH of a solution?

Answer 22

• Hydrogen ions (H+)
• Hydroxide ions (OH-)

Question 23

What happens to the pH value when hydrogen ion concentration increases?

Answer 23

The solution becomes more acidic.

Question 24

What happens to the pH value when hydroxide ion concentration increases?

Answer 24

The solution becomes more basic.

Question 25

Define buffer

Answer 25

Compound used to resist any change in pH of a solution ## Footnote Buffers help maintain pH homeostasis in bodily fluids.