The Chemistry of Life CHAPTER 2

Atoms, Ions, and Molecules SECTION 1:

OBJECTIVES 1.What three subatomic particles make up atoms? 2.How are all the isotopes of an element similar? 3.What are the two types of chemical bonds?

THE BIG IDEA Life Depends on chemistry Chemical reactions keep you alive

ATOM Basic unit of matter

DEMOCRITES

DALTON’S ATOMIC THEORY Dalton performed experiments, unlike Democritus, to test his theory on atomic structure. Theory included the following ideas: All elements are composed of submicroscopic indivisible particles called atoms. Atoms of the same element are identical. Atoms of different elements can physically mix together or chemically combine with one another in whole- number ratios to form compounds. Chemical reactions occur when atoms are separated, joined, or rearranged.

Protons - Neutrons - Electrons - Positively charged (+) Not charged (neutral) Negatively charged (-) SUBATOMIC PARTICLES Bind together to form the nucleus Electrons Protons Neutrons Nucleus

WHAT ARE THE 3 MAJOR PARTS OF AN ATOM? Proton Neutron Electron

DESCRIBE PROTON Protons are positively charged particles found in the atomic nucleus. Protons were discovered by Ernest Rutherford.. Experiments done in the late 1960's and early 1970's showed that protons are made from other particles called quarks. Protons are made from two 'up' quarks and one 'down' quark.

DESCRIBE NEUTRON Neutrons are uncharged particles found in the atomic nucleus. Neutrons were discovered by James Chadwick in Experiments done in the late 1960's and early 1970's showed that neutrons are made from other particles called quarks. Neutrons are made from one 'up' quark and two 'down' quarks.

DESCRIBE ELECTRON Electrons are negatively charged particles that surround the atom's nucleus. Electrons were discovered by J. J. Thomson in Electrons determine properties of the atom. Chemical reactions involve sharing or exchanging electrons.

DESCRIBE NUCLEUS The nucleus is the central part of an atom. It is composed of protons and neutrons. The nucleus contains most of an atom's mass. It was discovered by Ernest Rutherford in 1911.

DESCRIBE QUARK Believed to be one of the basic building blocks of matter. Quarks were first discovered in experiments done in the late 1960's and early 1970's. Three families of quarks are known to exist. Each family contains two quarks. The first family consists of Up and Down quarks, the quarks that join together to form protons and neutrons. The second family consists of Strange and Charm quarks and only exist at high energies. The third family consists of Top and Bottom quarks and only exist at very high energies.

DESCRIBE ISOTOPE Atoms that have the same number of protons but different numbers of neutrons

WHAT IS THE ELECTRON CLOUD MODEL? Model of the atom pictures the electrons moving around the nucleus in a region called an electron cloud. The electron cloud is a cloud of varying density surrounding the nucleus. The varying density shows where an electron is more or less likely to be. Atoms with electrons in higher energy levels have additional electron clouds of different shapes that also show where those electrons are likely to be. For more information, click here:

ELEMENT A pure substance that consists of just one type of atom

6 C Carbon Atomic number An elements atomic number = number of protons

Nonradioactive carbon-12Nonradioactive carbon-13Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 8 neutrons 6 electrons 6 protons 7 neutrons

6 C Carbon Mass number The Sum of protons and neutrons in the nucleus of an atom is its mass number

The weighted average of the masses of an elements isotope is called its atomic mass

RADIOACTIVE ISOTOPES Can be dangerous Can be used practically Radioactive dating Treat cancer Kill bacteria

COMPOUNDS A substance formed by the chemical combination of two or more elements in definite proportions Ex) H 2 O, NaCl

Table Salt

IONIC BONDS Formed when one or more electrons are transferred from one atom to another

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na + ) Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

If an atom loses an electron it becomes positive If an atom gains an electron it becomes negative

IONS Positively and negatively charged atoms

COVALENT BONDS Forms when electrons are shared between atoms

MOLECULE The structure that results when atoms are joined together by a covalent bond Smallest unit of most compounds

VAN DER WAALS FORCES A slight attraction that develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

HOMEWORK

1.Describe the structure of an atom. 2.Why do all isotopes of an element have the same chemical properties? 3.What is a covalent bond? 4.What is a compound? How are they related to molecules? 5.How do Van der Waals forces hold molecules together? 6.How are ionic bonds and Van der Waals forces similar? How are they different?

Properties of Water SECTION 2:

OBJECTIVES 1.Why are water molecules polar? 2.What are acidic solutions? 3.What are basic solutions?

THE BIG IDEA Much of our planet is covered in water Water is necessary for life to exist If life exists on other planets, there most likely is water present Water has many properties that make life possible

POLARITY (-) (+) The oxygen atom has a stronger attraction for electrons

HYDROGEN BONDS Because of waters partial charges, they can attract each other and create hydrogen bonds Not as strong as covalent or ionic bonds Waters ability to create multiple hydrogen bonds gives it many special properties

COHESION Attraction between molecules of the same substance

ADHESION Attraction molecules of different substances

MIXTURE Material composed of two or more elements or compounds that are physically mixed but not chemically combined Ex.) salt & pepper, earths atmosphere

SOLUTIONS Mixture of two or more substances in which the molecules are evenly distributed Ex. salt water Settles out over time

SOLUTIONS Cl - Water Cl - Na + Water Na +

SOLUTE Substance that is dissolved Ex. salt

SOLVENT The substance that does the dissolving Ex. Water

SUSPENSIONS Mixture of water and non-dissolved materials Ex. sugar solution, blood Separate into pieces so small, they never settle out

THE PH SCALE Indicated the concentration of hydrogen ions in a solution

Neutral Acid Base

ACIDS Any compound that forms H + (hydrogen) ions in solution

BASE A compound that produces OH - (hydroxide) ions in solution

BUFFERS Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden pH changes

HOMEWORK

1.Use the structure of a water molecule to explain why its polar 2.Compare acidic and basic solutions in terms of their H+ ion and OH- ion concentrations 3.What is the difference between a solution and a suspension? 4.What does pH measure? 5.The strong acid hydrogen fluoride (HF) can be dissolved in pure water. Will the pH of the solution be greater or less than 7?

Carbon-Based Molecules SECTION 3:

OBJECTIVE 1.What are the functions of each group of organic compounds?

LIFE’S BACKBONE Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms. As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain. Section 2-3 Interest Grabber

MethaneAcetyleneButadieneBenzene Isooctane

MACROMOLECULES “GIANT MOLECULES” Formed by a process called polymerization

MONOMERS Smaller units

POLYMERS Linked up monomers

CARBOHYDRATES Compounds made up of carbon, hydrogen, and oxygen atoms usually in a ratio of 1:2:1 Main source of energy The monomers of starch are sugars

Single sugar molecules are called monosaccharides The large macromolecules formed from monosaccharides are known as polysaccharides

Starch Glucose

LIPIDS Made mostly from carbon and hydrogen atoms Used to store energy

LIPID Glycerol Fatty Acids

PROTEINS Macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen Proteins are polymers of molecules called amino acids

AMINO ACIDS General structureAlanineSerine Carboxyl group

More than 20 different amino acids, can join to any other amino acid The instructions for arranging amino acids into many different proteins are stored in DNA Each protein has a specific role The shape of proteins can be very important

PROTEINS Amino Acids

NUCLEIC ACIDS Macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus Double Helix

NUCLEOTIDES Consists of 3 parts: 5-carbon sugar, phosphate group and nitrogen base Nitrogen Base 5-Carbon Sugar Phosphate group

2 KINDS OF NUCLEIC ACIDS RNA (ribonucleic acids) – contains sugar ribose DNA (deoxyribonucleic acid) – contains sugar deoxyribose

HOMEWORK

1.Name four groups of organic compounds found in living thing 2.Describe at least one function of each group of organic compounds 3.Compare the structures and functions of lipids and starches

Chemical Reactions and Enzymes SECTION 4 & 5:

OBJECTIVES 1.What happens to chemical bonds during chemical reactions? 2.How do energy changes affect whether a chemical reaction will occur? 3.Why are enzymes important to living things?

THE BIG IDEA Living things are made up of chemical compounds Everything that happens to an organism is based on chemical reactions

CHEMICAL REACTIONS A process that changes or transforms one set of chemicals into another

REACTANTS Elements or compounds that enter into a reaction

PRODUCTS Elements or compounds produced by a chemical reaction

EXAMPLE REACTION: GETTING RID OF CARBON DIOXIDE In the blood In the lungs CO 2 + H 2 0  H 2 CO 3 (carbonic acid) H 2 CO 3  CO 2 + H 2 O Released as you breathe

ENERGY IN REACTIONS Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants

ACTIVATION ENERGY The energy that is needed to get a reaction started

ENZYMES Some chemical reactions are too slow or have activation energies that are too high to make them practical for living tissue These chemical reactions are made possible by catalysts

CATALYST Substance that speeds up the rate of chemical reactions Work by lowering a reactions activation energy

ENZYME Biological catalysts Speed up reactions in cells Very specific Named for the reaction is catylzes Enzyme names always end in -ase

Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reaction pathway with enzyme Reactants Products

SUBSTRATES The reactants of enzyme catalyzed reactions The active site of the enzyme and the substrate have complementary shapes Fit like a lock and key

ENZYME ACTION Enzyme – substrate complex

Glucose Substrates ATP Substrates bind to enzyme Substrates are converted into products Enzyme-substrate complex Enzyme (hexokinase) ADP Products Glucose-6- phosphate Products are released Active site

REGULATION OF ENZYME ACTIVITY Enzymes are affected by any variable that affects chemical reactions 1.pH 2.Temperature 3.Concentration of enzyme

HOMEWORK

1.What happens to chemical bonds during chemical reactions 2.Describe the role of energy in chemical reactions 3.What are enzymes, and how are they important to living things? 4.Describe how enzymes work, including the role of the enzyme substrate complex 5.A change in pH can change the protein. How might a change in pH affect the function of an enzyme such as hexokinase (hint: think about the analogy of the lock and key)