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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
Section 1 Composition of Matter
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.
Section 1 Composition of Matter
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
Section 1 Composition of Matter
Section 1 Composition of Matter
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
Click below to watch the Visual Concept.
Visual Concept
Element
Section 1 Composition of Matter
Section 1 Composition of Matter
Chapter 2
Elements and Atoms, continued
• The Nucleus
– Protons and neutrons make up the nucleus of the
atom.
Section 1 Composition of Matter
Chapter 2
Elements and Atoms, continued
• 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.
Section 1 Composition of Matter
Chapter 2
Elements and Atoms, continued
• Isotopes
– Atoms of the same
element that have a
different number of
neutrons are called
isotopes.
Section 1 Composition of Matter
Chapter 2
Compounds
• Compounds consist of atoms of two or more
elements that are joined by chemical bonds in a fixed
proportion.
Chapter 2
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Visual Concept
Compounds
Section 1 Composition of Matter
Section 1 Composition of Matter
Chapter 2
Compounds, continued
• Covalent Bonds
– A covalent bond is
formed when two
atoms share
electrons.
Chapter 2
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Visual Concept
Covalent Bonding
Section 1 Composition of Matter
Section 1 Composition of Matter
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
Section 1 Composition of Matter
Chapter 2
Click below to watch the Visual Concept.
Visual Concept
Ionic Bonding
Section 1 Composition of Matter
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
Click below to watch the Visual Concept.
Visual Concept
Energy
Section 2 Energy
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
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Visual Concept
Activation Energy and Chemical Reactions
Section 2 Energy
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.
Section 3 Water and Solutions
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.
Section 3 Water and Solutions
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.
Section 3 Water and Solutions
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.
Section 3 Water and Solutions
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.
Section 3 Water and Solutions
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
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Visual Concept
Comparing Cohesion and Adhesion
Section 3 Water and Solutions
Section 3 Water and Solutions
Chapter 2
Hydrogen Bonding, continued
• Temperature Moderation
– Water has the ability to absorb a relatively large
amount of energy as heat and the ability to cool
surfaces through evaporation.
Section 3 Water and Solutions
Chapter 2
Hydrogen Bonding, continued
• Density of Ice
– Solid water is less dense than liquid water due to
the shape of the water molecule and hydrogen
bonding.
Section 3 Water and Solutions
Chapter 2
Solutions
• A solution consists of a solute dissolved in a
solvent.
Section 3 Water and Solutions
Chapter 2
Acids and Bases
• Ionization of Water
– Water ionizes into hydronium ions (H3O+) and
hydroxide ions (OH–).
Section 3 Water and Solutions
Chapter 2
Acids and Bases, continued
• Acids
– Acidic solutions contain more hydronium ions
than hydroxide ions.
Section 3 Water and Solutions
Chapter 2
Acids and Bases, continued
• Bases
– Basic solutions contain more hydroxide ions than
hydronium ions.
Chapter 2
Click below to watch the Visual Concept.
Visual Concept
Bases
Section 3 Water and Solutions
Section 3 Water and Solutions
Chapter 2
Acids and Bases, continued
• 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
Section 3 Water and Solutions
Section 3 Water and Solutions
Chapter 2
Acids and Bases, continued
• Buffers
– Buffers are chemicals that neutralize the effects
of adding small amounts of either an acid or a
base to a solution.
Chapter 2
Click below to watch the Visual Concept.
Visual Concept
pH
Section 3 Water and Solutions
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