Chapter 2 Chemical Context Of Life

Question 1

Element is:

Answer 1

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

Question 2

A compound is:

Answer 2

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

Question 3

Of the 92 natural elements, only about ______% are essential elements needed by an organism to live

Answer 3

20-25

Question 4

Oxygen, carbon, hydrogen, and nitrogen make up about _____% of body mass

Answer 4

96.3

Question 5

An atom is:

Answer 5

The smallest unit of matter that still retains the properties if an element

Question 6

Atomic mass measured in:

Answer 6

Daltons

Question 7

Isotopes

Answer 7

Different number of neutrons

Question 8

Energy is the capacity to cause

Answer 8

Change

Question 9

Covalent bond

Answer 9

Sharing a pair of valence electrons

Question 10

Two or more atoms held together by covalent bonds constitute a:

Answer 10

Molecule

Question 11

Molecules composed of two or more types of atoms are called:

Answer 11

Compounds

Question 12

Most of the strongest bonds in organisms are:

Answer 12

Covalent bonds that form a cells molecules

Question 13

Weak bonds include

Answer 13

Ionic, hydrogen, and van see waals

Question 14

Four emergent properties of water that contribute to life:

Answer 14

Cohesive behavior
Ability to moderate temperature
Expansion upon freezing
Versatility as a solvent

Question 15

Thermal energy

Answer 15

Measure of the total amount of kinetic energy due to molecular motion

Question 16

Water reaches its greatest density at

Answer 16

4 deg c

Question 17

Solution

Answer 17

A homogeneous mixture of substances

Question 18

Hydration shell

Answer 18

When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water