CHEMISTRY

The structure and function of all living things are governed by the laws of Chemistry (The Central Science).  An understanding of the fundamental principles of chemistry will give you a better understanding of living things and how they function.

COMPOSITION OF MATTER

OBJECTIVES:  Define element, atom, compound, and molecule.  Draw a model of the structure of an atom.  Explain what determines an atom's stability.  Contrast ionic and covalent bonding.

MATTER

1. MATTER -  EVERYTHING IN THE UNIVERSE IS MADE OF MATTER. Matter is defined as Anything that has Mass and takes up Space.

2. MASS - The measurement of the amount of Matter in an object OR is the Quantity of Matter an object has.

3. MASS and WEIGHT are NOT the SAME.

4. Weight is the pull of gravity on an objects mass.  You would be of the same Mass on the Moon but you Weight would be different because the Moon has less Gravitational Pull. (APPROX.. 1/6)

5. Matter is Classified (divided) into FOUR STATES:

        A. SOLID - Anything that has BOTH A DEFINITE VOLUME and a DEFINITE SHAPE.  A rock is a solid, solid matter can be picked up and carried around without having to place it in a special container.

        B. LIQUID - Anything that has DEFINITE VOLUME but NO DEFINITE SHAPE.  A key property of a liquid is that they FLOW and can be POURED.

        C. GAS - Has NO DEFINITE VOLUME and NO DEFINITE SHAPE.  A Gas ALWAYS TAKES BOTH THE VOLUME AND THE SHAPE OF ANY CONTAINER INTO WHICH IT IS PLACED.  If a gas is NOT in a container, it will spread out as far as it can.

        D. PLASMA - Has NO DEFINITE VOLUME OR SHAPE AND IS COMPOSED OF ELECTRICAL CHARGED PARTICLES.

6. Chemical Changes in matter are essential to all life processes.  Biologists study chemistry because all living things are made of the same kinds of matter that make up nonliving things.

ELEMENTS

1. ELEMENTS ARE PURE SUBSTANCES THAT CANNOT BE BROKEN DOWN CHEMICALLY INTO SIMPLER KINDS OF MATTER.

2. More than 100 elements have been identified, though Fewer than 30 are Important in Living Things.  (The Periodic Table of Elements)

3. All of the Elements are arranged on a Chart known as THE PERIODIC TABLE.  Among the information provided in The Periodic Table are the ATOMIC NUMBER, THE CHEMICAL SYMBOL, AND THE ATOMIC MASS FOR EACH ELEMENT.

4. More than 90 Percent of the Mass of living things is composed of JUST FOUR ELEMENTS:  OXYGEN, O, CARBON, C, HYDROGEN, H, AND NITROGEN, N.

5. Each Element has different Chemical Symbol which consist of One or Two Letters.

6. In most cases, the Symbol Derives from the First Letter or Other Letters in the Name of the Element, like - C for Carbon or Cl for Chlorine.

7. Some of the Symbol Names come form their Latin Name - Na for Sodium (Natrium) or K for Potassium (Kalium).

ATOMS

1. The Simplest Particle of an Element that RETAINS ALL of the PROPERTIES of the Element is an ATOM.  Atoms are so small that their TRUE Structure Cannot be Observe, but scientist have developed Models that describe the Structure and Properties of the Atom.

2. An Atom consists of THREE Kinds of Particles, PROTONS AND NEUTRONS FOUND IN THE ATOMS NUCLEUS, AND ELECTRONS.

3. The Central Core of an Atom is called the NUCLEUS, Most of the MASS of an Atom is concentrated in its Nucleus and consists of Two Kinds of Particles:
        A. PROTONS:  A POSITIVE CHARGED PARTICLE.  All Atoms of a given Element have the SAME Number of Protons.  The Number of Protons in an Atom is called the ATOMIC NUMBER which appears Above the Chemical Symbol.

        B. NEUTRONS - NEUTRONS HAVE NO ELECTRICAL CHARGE.  The number of Neutrons in an Atom is derived by the ATOMIC MASS MINUS THE ATOMIC NUMBER.  OR THE NUMBER OF PROTONS PLUS THE NUMBER OF NEUTRONS EQUAL THE ATOMIC MASS.

4. The number of Positively Charged Protons is Balanced by an Equal Number of small,  NEGATIVELY CHARGED PARTICLES called ELECTRONS (e-).

5. The Electrical Charges of the Electrons OFFSET those of the Protons, making the NET Electrical Charge of an Atom ZERO.

6. Electrons are high-energy particles with very little mass.  They MOVE About the Nucleus at very High Speeds in one of seven different ENERGY LEVELS.

7. Electrons in OUTER Energy Levels have MORE Energy than those in INNER Levels.
 

8. Each Energy Level (shell) can hold only a certain number of electrons. The First Level, Nearest the Nucleus, can only hold TWO Electrons.  The Second and other OUTER Levels can hold up to EIGHT Electrons each.

9. A STABLE ATOM IS AN ATOM THAT HAS A FULL OUTER LEVEL.
 
   

COMPOUNDS

1. Under Natural Conditions, MOST Elements DO NOT Exist by themselves; Most elements COMBINE with other Elements.

2. A PURE SUBSTANCE that is made up of Atoms of TWO or MORE Elements is called a COMPOUND.

3. The Proportion of each kind of Atom is FIXED,  A CHEMICAL FORMULA Shows the KIND and PROPORTION of Atoms each Element that forms a particular Compound - WATER = H20 - indicates TWO HYDROGEN Atoms to ONE OXYGEN Atom.

4. The Physical and Chemical Properties of a Compound DIFFER form the Physical and Chemical Properties of the individual Elements that compose it.  Both H and O are found as gases, but the combine to form Water a Liquid.

5. The Tendency of elements to combine and form Compounds depends on the Number and Arrangement of Electrons in their Atoms.

6. An Atom is Chemically Stable when its Outermost Energy Level is Filled (8 E-)

7. Most Atoms are NOT Stable in their Natural State, so they tend to React, or Combine with other Atoms (CHEMICAL REACTIONS), in ways that make the Atoms More Stable.

8. Most Atoms tend to undergo CHEMICAL REACTIONS,  Combining in ways that Cause their Atoms to Become Stable.  In Chemical Reactions, CHEMICAL BONDS are broken, Atoms are Rearranged, and New Chemical Bonds, or Attachments, are formed.

COVALENT BONDS - SHARING OF ELECTRONS

1. A COVALENT BOND forms when TWO Atoms SHARE One or MORE Pairs of Electrons. 

2. Water is made up by Atoms Held together by a Covalent Bonds.  In the Presence of one another, hydrogen atoms and oxygen atoms can achieve stability by sharing pairs of electrons in a ration of TWO Atoms of Hydrogen to ONE Atom of Oxygen.

3. Covalent Bonding Results in the Formation of MOLECULES.

4. A MOLECULE is the Simplest Part of a Substance that Retains all the Properties of the Substance and that can Exist in a Free State.

5.   Water formation is an example of a Molecule of Water.

IONIC BONDING - TRANSFER OF ELECTRONS

1. IONIC BOND IS A BOND FORMED BY ELECTRICAL ATTRACTION BETWEEN TWO OPPOSITLY CHARGED IONS.

2. AN ATOM OR MOLECULE WITH AN ELECTRICAL CHARGE IS CALLED AN ION.

3. If an Atom has More Protons than Electrons it is POSITIVELY CHARGED (+).

4. If an Atom has More Electrons than Protons it is NEGATIVELY CHARGED (-)

 The formation of Table Salt (NaCl) is an example of an IONIC BOND:

    A. A Sodium Atom (Na) has ONE outer electron.

    B. A Chlorine Atom (Cl) has  SEVEN outer electrons.

    C. To become stable, the One outer E- of a Na atom is transferred to a Cl atom.  Na+

    D. To become more stable, Cl gains the E- from Na Atom.  Cl-.

    E. Because Positive and Negative Electrical Charges attract each other, the Na+ and Cl- attract each other.  This Attraction is called an IONIC BOND.

    F. The resulting Compound, Sodium Chloride, NaCl, is an Ionic Compound and is familiar to you as Common Table Salt.

ENERGY

One important characteristic of all living things is that they Use Energy.  The amount of Energy in the Universe remains the same over time, but Energy can change in form constantly.  It is the flow of energy- from the sun to and through almost every organism on Earth- that biologist seek to understand when they study the chemistry of living things.

OBJECTIVES:  List the Three States of matter, and explain how matter can change state.  Describe how energy changes are involved in chemical reactions.  Explain how enzymes affect chemical reactions in organisms.  Explain what a redox reaction is.

ENERGY AND MATTER

1. Scientist define ENERGY as the ability to do work or cause change.

2. Energy can occur in various forms, and one form of energy can be converted to another form.

3. Some forms of energy important to living things include CHEMICAL ENERGY, THERMAL ENERGY, ELECTRICAL ENERGY, AND MECHANICAL ENERGY.

4. Biologist often refer to FREE ENERGY, the Energy in a system that is available for work.  For example, in a Cell, it is the Energy that is available to Fuel Cell Processes.

5. As Energy Flows through an organism, it may be converted from one form to another- the Food you eat is changed by your body from the Chemical Energy found in Food into Thermal and Mechanical Energy, to be used by your body.

STATES OF MATTER

1. ALL Atoms and Molecules is any Substance are in CONSTANT MOTION.

2. The RATE at which Atoms or Molecules of a Substance MOVE DETERMINES ITS STATE.
 Matter is Classified (divided) into THREE STATES:

    A.  SOLID - Anything that has BOTH A FIXED VOLUME and SHAPE.  A rock is a solid, solid matter can be picked up and carried around without having to place it in a special container. Particles of a solid are Tightly linked together and they Vibrate in Place.

    B.  LIQUID - Anything that has a FIXED VOLUME but NO DEFINITE SHAPE.  A key property of a liquid is that they FLOW and can be POURED.  Particles of a Liquid are NOT as Tightly Linked as those in a Solid.  Its Particles move more freely than those of a solid, giving liquid the ability to Flow.

    C.  GAS - Has NO DEFINITE VOLUME and NO DEFINITE SHAPE.  A Gas ALWAYS TAKES BOTH THE VOLUME AND THE SHAPE OF ANY CONTAINER INTO WHICH IT IS PLACED.  If a gas is NOT in a container, it will spread out as far as it can.  Particles of Gas move Most Rapidly.  Gas Particles have Little or No Attraction to each other.

3. To cause a Substance to Change from a Solid to a Liquid and from a Liquid to a Gas, Thermal Energy (Heat) must be Added to the Substance.

ENERGY AND CHEMICAL REACTIONS

1. Living Things undergo many thousand of Chemical Reactions as part of their life process.

2. CO2 + H20 = H2CO3 is a sample Chemical Reaction.  Carbon Dioxide and Water can Combine to form Carbonic Acid.

3. The REACTANTS are on the LEFT Side of the Equation.  The PRODUCTS are on the RIGHT side of the Equation.

4. In a Chemical Reaction, Bonds present in the Reactants are Broken. The Elements are Rearranged, and NEW Compounds are formed as the Products.

5. Much of the Energy your body need is provided by Sugars from Food.

6. You body undergoes a series of Chemical Reactions in which Sugars are broken down to Carbon Dioxide and Water.  In this process, energy is released for use by the body.  (Breaking Chemical Bonds Releases Energy)

7. Chemical Reaction that involve a Net Release of Free Energy are called EXERGONIC REACTIONS.

8. Reactions that involve a Net Absorption of Free energy are called ENDERGONIC REACTIONS.

9. For most Chemical Reactions to begin, Energy Must Be Added to the Reactants.

10. In many Chemical Reactions, the AMOUNT of Energy NEEDED to START the Reaction, called ACTIVATION ENERGY, IS HIGH.

11. Certain Chemical Substances, known as CATALYSTS, Reduce the amount of Activation energy Needed.  A Reaction in the presence of a Catalyst will proceed Spontaneously or with the addition of a small amount of Energy.

12. ENZYMES are an important class of Catalysts in living things.  A single organism may have thousands of different Enzymes.

REDUCTION-OXIDATION REACTIONS

1. Many of the Chemical Reactions that help Transfer Energy in living things involve the TRANSFER OF ELECTRONS.

2. These Reactions in which E- are Transferred Between Atoms are known as REDUCTION-OXIDATION REACTIONS, OR REDOX REACTIONS.  The Formation of Table Salt

3. In an OXIDATION REACTION, a Reactant LOSES One or More E-, becoming more POSITIVE IN CHARGE.  The Sodium Atom undergoes Oxidation to form Na+ ion.

4. In a REDUCTION REACTION, a Reactant GAINS One or more E-, Becoming more NEGATIVE IN CHARGE.  The Chlorine Atom undergoes Reduction to form Cl- ion.

5. REDOX REACTIONS ALWAYS OCCUR TOGETHER.  An Oxidation Reaction occurs, and the E- given up by one substance is then accepted by another substance in a Reduction Reaction.

SOLUTIONS

The chemistry of living things involves the study of solutions.  A large portion of the Mass of living things is Water, and the Chemical Reactions of life occur for the most part in water.  The electricity that courses through your nerves is transmitted through watery pathways of dissolved ions.  Chemical messengers (Hormones) that regulate your body's metabolism move through the watery medium of you blood.

OBJECTIVES:  Define solution, solute, solvent, and concentration.  Explain the dissociation of water.  Contrast properties of acids and bases.  Describe the use of the pH scale.  Explain the action of buffers.

DESCRIBING SOLUTIONS

1.  A SOLUTION is a Mixture in which One or More Substances are UNIFORMLY Distributed in Another Substance.  Solutions can be mixtures of liquids, solids, or gases.

2.  Think of Sugar Water (The Solution) - the Sugar is dissolved in the Water and is Uniformly Distributed.

    A. The SOLUTE (Sugar) is the Substance Dissolved in the Solution (Sugar Water).  The particles that compose the Solute may be Ions, Atoms, or Molecules.

    B. The SOLVENT (Water) is the Substance in which the Solute is dissolved.

    C. When Sugar, a Solute, and Water, a Solvent, are mixed, a Solution of Sugar Water Results.

    D.   Though the Sugar Dissolves in the Water, Neither of the molecules are Altered Chemically.  If the Water is boiled away, the Sugar Molecules remain and are Unchanged.

3.  Solutions can be composed of various proportions of a given Solute in a given Solvent.  1 cup of Sugar to 3 cups of water.

4.  The CONCENTRATION of a Solution is the Measurement of the amount of Solute dissolved in a Fixed amount of the Solution.  The More Solute dissolved, the Greater the Concentration of the Solution.

2.  A SATURATED SOLUTION is one in which NO MORE Solute can dissolve.  Keep adding sugar to water, and eventually the water will become Saturated, and no more sugar will dissolve.

3.  AQUEOUS SOLUTIONS are Solutions in which Water is the Solvent.  They are universally important to living things.

4.  Most nutrients that plants need are in Aqueous Solutions in moist soil.  Your Body Cells exist in an Aqueous Solution of Intercellular Fluid and are themselves filled with Fluid.

ACIDS AND BASES

1. One of the most important aspects of living systems is the degree of its acidity or alkalinity (Base).

2. In water, the force of attraction between molecules is so strong that the oxygen atom of one molecule can actually remove the hydrogen from other water molecules.

3. This breaking apart of the water molecule into TWO Ions of opposite charge is called DISSOCIATION OF WATER.

                H20 = H+  +  OH-

4. One molecule of water dissociates to form TWO Ions, H+ and OH-.  The OH- is known as the HYDROXIDE ION.  The free H+ ion can react with another water molecule:

            H+  +  H2O = H3O+

5. The H3O+ ion is known as the HYDRONIUM ION.

6. ACIDITY or ALKALINITY is a measure of the relative amounts of Hydronium Ions and Hydroxide Ions dissolved in a Solution.

    A. NEUTRAL SOLUTION - If the number of Hydronium Ions in a solution EQUALS the number of Hydroxide Ions, the Solution is said to be Neutral.

    B. ACID - If the number of Hydronium Ions (H3O+) in a Solution is GREATER than the number of Hydoxide Ions (OH-), the Solution is an ACID.  Acids tend to have a SOUR Taste and in concentrated forms are Highly Corrosive.

    C. BASE - If a Solution contains MORE Hydroxide Ions (OH-) than Hydronium Ions (H3O+) it is defined as a BASE.  Bases tend to FEEL Slippery (soap) and have a BITTER Taste.

pH

1. Scientist have developed a Scale for comparing the relative concentration of Hydronium Ions to Hydroxide Ions in Solution called the pH SCALE.

2. The pH Scale ranges from 0 to 14.

3. A Solution with a pH of 0 is VERY ACIDIC.

4. A Solution with a pH of 7 is NEUTRAL.

5. A Solution with a pH of 14 is VERY BASIC.

6. The pH of an solution can be measured with Litmus Paper or with some other chemical indicators that changes color at various pH Levels.

BUFFERS

1. The control of pH is important for Living Things.

2. Enzymes can function only within a very narrow pH range.

3. The control of pH in organisms is often accomplished with BUFFERS.

4. BUFFERS are Chemical Substances that NEUTRALIZE Small amounts of either Acid or a Base added to a solution.

5. Some of your body's fluids, such as Stomach Acid and Urine, are Acidic.  Others, such as Intestinal Fluid and Blood are Basic.

6. Complex Buffering Systems maintain the pH Values of your body's many fluids at Normal or Safe Levels.