Chapter 2 Chemistry of Life Modern Biology Textbook Holt

Objectives Chapter 2 Define the term matter. 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.

Matter Chapter 2 Matter is anything that occupies space and has mass. 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.

Elements and Atoms Chapter 2 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.

Elements and Atoms, continued Section 1 Composition of Matter Chapter 2 Elements and Atoms, continued The Nucleus Protons and neutrons make up the nucleus of the atom. Protons are positively charged particles. Neutrons have no charge (neutral). Together the mass of the protons and neutrons in the nucleus of an atom makes up the atom’s atomic mass.

Elements and Atoms, continued 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.

Elements and Atoms, continued 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 Compounds, continued Covalent Bonds Section 1 Composition of Matter Chapter 2 Compounds, continued Covalent Bonds A covalent bond is formed when two atoms share electrons.

Chapter 2 Compounds, continued Ionic Bonds 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.

Section 1 Composition of Matter Chapter 2 Ionic Bonding

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.

Chapter 2 Energy and Matter States of Matter 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.

Energy and Chemical Reactions Section 2 Energy Chapter 2 Energy and Chemical Reactions Reactants are substances that enter chemical reactions. Products are substances produced by chemical reactions.

Energy and Chemical Reactions Section 2 Energy Chapter 2 Energy and Chemical Reactions

Energy and Chemical Reactions, continued 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. 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. 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.

Chapter 2 Polarity, continued Solubility of Water 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.

Chapter 2 Hydrogen Bonding 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.

Hydrogen Bonding, continued 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.

Hydrogen Bonding, continued 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. 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.

Acids and Bases, continued Section 3 Water and Solutions Chapter 2 Acids and Bases, continued Ionization of Water Water ionizes into hydronium ions (H3O+) and hydroxide ions (OH–). Acids Acidic solutions contain more hydronium ions than hydroxide ions.

Acids and Bases, continued Section 3 Water and Solutions Chapter 2 Acids and Bases, continued Bases Basic solutions contain more hydroxide ions than hydronium ions. Buffers Buffers are chemicals that neutralize the effects of adding small amounts of either an acid or a base to a solution.

Acids and Bases, continued 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.

Section 3 Water and Solutions Chapter 2 The pH Scale