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Chemistry of Life Chapter 2

Table of Contents

Section 1 Composition of Matter

Section 2 Energy

Section 3 Water and Solutions


Chapter 2

Objectives

• Define the term matter.

• Explain the relationship between elements and

atoms.

• Draw and label a model of the structure of an atom.

• Explain how compounds affect an atom’s stability.

• Contrast covalent and ionic bonds.


Chapter 2

Matter

• Matter is anything that occupies space and has

mass.

• Mass is the quantity of matter an object has.

Chapter 2

Click below to watch the Visual Concept.

Visual Concept

Matter


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Chapter 2

Elements and Atoms

• Elements are made of a single kind of atom and

cannot be broken down by chemical means into

simpler substances.

• Atoms are composed of protons, neutrons, and

electrons.

Chapter 2


Visual Concept

Element


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Chapter 2

Elements and Atoms, continued

• The Nucleus

– Protons and neutrons make up the nucleus of the

atom.


Chapter 2


• Electrons

– Electrons move about the nucleus in orbitals.

– An orbital is a three-dimensional region around a nucleus that indicates the probable location of an electron.


Chapter 2


• Isotopes

– Atoms of the same

element that have a

different number of

neutrons are called

isotopes.


Chapter 2

Compounds

• Compounds consist of atoms of two or more

elements that are joined by chemical bonds in a fixed

proportion.

Chapter 2


Visual Concept

Compounds


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Chapter 2

Compounds, continued

• Covalent Bonds

– A covalent bond is

formed when two

atoms share

electrons.

Chapter 2


Visual Concept

Covalent Bonding


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Chapter 2

Compounds, continued

• Ionic Bonds

– An ionic bond is formed when one atom gives up

an electron to another. The positive ion is then

attracted to a negative ion to form the ionic bond.

Chapter 2

Ionic Bonding


Chapter 2


Visual Concept

Ionic Bonding


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Section 2 Energy

Chapter 2

Objectives

• Describe the physical properties of each state of

matter.

• Describe the role of reactants and products in

chemical reactions.

• Explain the relationship between enzymes and

activation energy.

• Explain how oxidation and reduction reactions are

linked.

Section 2 Energy

Chapter 2

Energy and Matter

• States of Matter

– Addition of energy

to a substance can

cause its state to

change from a solid

to a liquid and

from a liquid

to a gas.

Chapter 2


Visual Concept

Energy

Section 2 Energy

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Section 2 Energy

Chapter 2

Energy and Chemical Reactions

• Reactants are substances that enter chemical

reactions.

• Products are substances produced by chemical

reactions.

Chapter 2

Energy and Chemical Reactions

Section 2 Energy

Section 2 Energy

Chapter 2

Energy and Chemical Reactions, continued

• Activation Energy

– Enzymes lower the amount of activation energy

necessary for a reaction to begin in living systems.

Chapter 2


Visual Concept

Activation Energy and Chemical Reactions

Section 2 Energy

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Section 2 Energy

Chapter 2

Energy and Chemical Reactions, continued

• Oxidation Reduction Reactions

– A chemical reaction in which electrons are

exchanged between atoms is called an oxidation-

reduction reaction.


Chapter 2

Objectives

• Describe the structure of a water molecule.

• Explain how water’s polar nature affects its ability to

dissolve substances.

• Outline the relationship between hydrogen bonding

and the different properties of water.

• Identify the roles of solutes and solvents in solutions.

• Differentiate between acids and bases.


Chapter 2

Polarity

• Water is considered to be a polar molecule due to an

uneven distribution of charge.

• The electrons in a water molecule are shared

unevenly between hydrogen and oxygen.


Chapter 2

Polarity, continued

• Solubility of Water

– The polarity of water makes it effective at

dissolving other polar substances such as sugars,

ionic compounds, and some proteins.


Chapter 2

Hydrogen Bonding

• A hydrogen bond is the

force of attraction

between a hydrogen

molecule with a partial

positive charge and

another atom or

molecule with a partial or

full negative charge.


Chapter 2

Hydrogen Bonding, continued

• Cohesion and Adhesion

– Cohesion is an attractive force that holds

molecules of a single substance together, such as

water molecules.

– Adhesion is the attractive force between two

particles of different substances, such as water

molecules and glass molecules.

Chapter 2


Visual Concept

Comparing Cohesion and Adhesion


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Chapter 2


• Temperature Moderation

– Water has the ability to absorb a relatively large

amount of energy as heat and the ability to cool

surfaces through evaporation.


Chapter 2


• Density of Ice

– Solid water is less dense than liquid water due to

the shape of the water molecule and hydrogen

bonding.


Chapter 2

Solutions

• A solution consists of a solute dissolved in a

solvent.


Chapter 2

Acids and Bases

• Ionization of Water

– Water ionizes into hydronium ions (H3O+) and

hydroxide ions (OH–).


Chapter 2

Acids and Bases, continued

• Acids

– Acidic solutions contain more hydronium ions

than hydroxide ions.


Chapter 2


• Bases

– Basic solutions contain more hydroxide ions than

hydronium ions.

Chapter 2


Visual Concept

Bases


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Chapter 2


• pH

– Scientists have developed a scale for comparing

the relative concentrations of hydronium ions and

hydroxide ions in a solution. This scale is called

the pH scale, and it ranges from 0 to 14.

Chapter 2

The pH Scale



Chapter 2


• Buffers

– Buffers are chemicals that neutralize the effects

of adding small amounts of either an acid or a

base to a solution.

Chapter 2


Visual Concept

pH


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