The Chemical Context of Life

Question 1

Organisms are composed of what?

Answer 1

Matter

Question 2

What is matter?

Answer 2

Anything that takes up space and has mass

Question 3

What is an element?

Answer 3

A substance that cannot be broken down into other substances by chemical reactions

Question 4

What is a compound?

Answer 4

A substance consisting of two or more elements in a fixed ratio

Question 5

Matter consists of what?

Answer 5

Chemical elements in pure form and in combinations called compounds

Question 6

What are the elements of life?

Answer 6

Carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus, which take up 97% of of mass in the human body

Question 7

What are atoms?

Answer 7

The smallest unit of matter that can still retain the properties of an element

Question 8

What is an element’s atomic number?

Answer 8

The number of protons in its nucleus

Question 9

What is an element’s mass number?

Answer 9

The sum of protons plus neutrons in the nucleus

Question 10

What is atomic mass?

Answer 10

The atoms total mass

Question 11

What are isotopes?

Answer 11

Two atoms of an element that differ in the number of neutrons

Question 12

What are radioactive isotopes?

Answer 12

Isotopes that decay spontaneously, giving off particles and energy

Question 13

What is energy?

Answer 13

The capacity to cause change

Question 14

What is potential energy?

Answer 14

The energy that matter possesses because of its location or structure

Question 15

Matter has a natural tendency to move toward what?

Answer 15

The lowest possible state of potential energy

Question 16

How do electrons of an atom differ?

Answer 16

In their amounts of potential energy based on their distance from the nucleus

Question 17

How do changes in potential energy of electrons occur?

Answer 17

In steps of fixed amounts

Question 18

Where are electrons found?

Answer 18

In electron shells, each with a characteristic average distance and energy level

Question 19

How much energy are in the shells of an atomic nucleus?

Answer 19

The energy level increases with each shell

Question 20

What are valence electrons?

Answer 20

Those in the outermost shell, or the valence shell

Question 21

How is the chemical behavior of an atom determined?

Answer 21

By the number of valence electrons

Question 22

When is an element chemically inert?

Answer 22

When it has a full valence shell

Question 23

What is an orbital?

Answer 23

The three-dimensional space where an electron is found 90% of the time

Question 24

How do atoms interact?

Answer 24

In a way that completes their valence shells

Question 25

What does it mean if two or more elements are in the same row?

Answer 25

They have the same period

Question 26

What does it mean if two or more elements are in the same column?

Answer 26

They have the same group

Question 27

How are atoms able to stay close together when sharing valence electrons?

Answer 27

Chemical bond

Question 28

What is a covalent bond?

Answer 28

The sharing of a pair of valence electrons by two atoms

Question 29

What is a molecule?

Answer 29

Two or more atoms held together by covalent bonds

Question 30

What is a single bond?

Answer 30

The sharing of one pair of valence electrons

Question 31

What is a double bond?

Answer 31

The sharing of two pairs of valence electrons

Question 32

What is a nonpolar covalent bond?

Answer 32

The atoms share the electron equally

Question 33

What is electronegativity?

Answer 33

An atom's attraction for the electrons in a covalent bond

Question 34

The more electronegative an atom is...

Answer 34

The more strongly it pulls shared electrons toward itself

Question 35

What is a polar covalent bond?

Answer 35

When one atom is more electronegative and the atoms do not share the electron equally

Question 36

What is a positively charged ion called?

Answer 36

A cation

Question 37

What is a negatively charged ion called?

Answer 37

An anion

Question 38

What is an ionic bond?

Answer 38

Anions and cations attract each other

Question 39

What is a hydrogen bond?

Answer 39

A hydrogen atom is covalently bonded to one electronegative atom while it is also attracted to another electronegative atom

Question 40

What is a chemical reaction?

Answer 40

The making and breaking of chemical bonds

Question 41

What is a reactant?

Answer 41

The starting molecules of a chemical reaction

Question 42

What is a product?

Answer 42

The resulting molecules of a chemical reaction