Chapter 2: Chemistry Essential Question: Why do you need to know some basic chemistry in order to study biology?

I. Composition of Matter Matter: anything that occupies space and has mass 1. Mass: quantity of matter that an object has 2. Weight: pull of gravity on an object 3. Chemical changes in matter are essential to all life processes

B. Elements: pure substances that cannot be broken down into simpler kinds of matter 1. Oxygen, carbon, hydrogen, and nitrogen make up most of the living things 2. Elements on the periodic table contain the chemical symbol, atomic number, and atomic mass

C. Atoms: simplest particle of an element 1. Nucleus: center of the atom with most of the mass a) proton: positive charge b) neutron: no charge

2. Electrons: high energy, negatively 2. Electrons: high energy, negatively charged particle with little mass a) energy levels: location of the electrons with different amounts of energy b) first level holds 2 electrons c) second level holds 8 electrons Electron cloud

D. Compounds: pure substance that is made up of atoms of two or more elements 1. Chemical formula: proportion of atoms of each element (H2O) 2. Chemical reactions: rearrangement of atoms 3. Bonds: attachments a) Covalent bond: two atoms share one or more pairs of electrons b) Ionic bond: positively charged particle and negatively charged particle combine Video clip

4. Molecule: simplest part of a substance that retains all of the properties of the substance 5. Ion: atom with an electrical charge Example: Na+ and Cl-

II. Energy: ability to do work or cause change A. Energy in living things 1. Energy can be converted to different forms (light and heat) Ex: digest your food, body changes chemical energy in food into thermal and mechanical energy 2. Free energy: energy available to do work Energy 3. States of matter: solid, liquid, or gas: heat must be added or removed to cause a change in state

B. Energy and chemical reactions: living things undergo many thousands of reactions every day 1. Reactants: starting materials (left side) 2. Products: what is made (right side) CH4 + O2 CO2 + H2O Energy can be absorbed or released

3. Exergonic / Exothermic: release of energy 4. Endergonic / Endothermic: gain of energy 5. Activation energy: energy needed to start a reaction 6. Catalysts: substance that speeds up a reaction 7. Enzymes: type of catalysts in living things Enzyme

8. Redox reactions: reactions in which electrons are transferred between atoms a) Oxidation: reactant loses electrons b) Reduction: reactant gains electrons Redox

TED Talk

III. Water A. Polarity: positive and negative regions 1. Water’s biological functions comes from its chemical structure 2. Oxygen has a negative charge and hydrogen has a positive charge so water is polar 3. Water dissolves many substances because it is polar

B. Hydrogen Bonding: bond between hydrogen and nitrogen, oxygen, or fluorine 1. Weak bond that causes water to cling to itself 2. Cohesion: attractive force between particles of the same kind 3. Adhesion: attractive force between unlike substances Cohesion and Adhesion

4. Capillarity: water moves upward through narrow tubes against the force of gravity 5. Temperature moderation: water absorbs large amounts of energy which helps to keep cells at a constant temperature

IV. Solutions A. Describing Solutions 1. Solution: mixture in which one or more substances are uniformly distributed in another substance 2. Solute: substance dissolved in the solution 3. Solvent: substance in which the solute is dissolved 4. Concentration: measurement of the amount of solute dissolved in the solution

5. Saturated solution: no more solute can dissolve 6. Aqueous solution: water is the solvent Aqueous solution

B. Acids and Bases 1. Dissociation: breaking apart water into two ions (H2O  H+ + OH-) 2. Acid: solution with greater number of H+ than OH- a) sour taste b) corrosive 3. Base: solution with greater number of OH- than H+ (alkaline) a) bitter taste b) slippery

4. pH scale: scale from 0-14 a) acid: 0-6 b) base: 8-14 c) neutral: 7 Acids and Bases 5. Buffer: substances that neutralize small amounts of either an acid or a base a) Important in maintaining pH values of your body’s fluids (blood)