Chapter 2 The Chemistry of Life

What’s the matter? All of the materials around you are made up of matter. You are made up of matter, as are the chair you sit on and the air you breathe. 1. Give an example of solid matter. 2. Give an example of liquid matter. 3. Give an example of gaseous matter. 4. Is all matter visible? 5. Does all matter take up space?

2-1 The Nature of Matter

Atoms -Basic unit of matter (nonliving) -Contains subatomic particles -Protons -+ charge -In nucleus -Neutrons -No charge -In nucleus -Electrons -Negative charge -Constant motion -Around nucleus -Attracted to protons (opposite charges attract)

Elements and Isotopes Element – pure substance that has one type of atom -100 elements known - symbols have 1 or 2 letters - # protons is the atomic number -mass number is the # neutrons + #protons 6 C Carbon

Magnesium12 Iron26Atom 13 SulfurS16 BerylliumAtom 24 Carbon12 U92143 OxygenO ion Gold11878 SodiumNa+1 ion C68

Elements and Isotopes Isotope – atoms of the same element but a different number of neutrons -identified by their mass numbers - due to same number of electrons between isotopes, all elements have the same chemical properties

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

Elements and Isotopes Radioactive isotopes -contain unstable nuclei -nuclei break down at a constant rate over time -give off radiation

Elements and Isotopes Radioactive isotopes can be used: -to determine the ages of rocks and fossils. -to treat cancer. -to kill bacteria that cause food to spoil. -as labels or “tracers” to follow the movement of substances within an organism.

Chemical Compounds Compound – substance formed by the combination of 2 or more elements - chemical properties very different from elements that form it

Chemical Compounds Chemical Formula Water Table Salt Hydrochloric Acid Glucose

Chemical Bonds Compounds are held together by chemical bonds -bond formation involves the electrons surrounding the atomic nucleus -electrons to be used during bonding are called valence electrons

Chemical Bonds Ionic bond Ionic bond – formed when 1+ electrons are transferred from one atom to another -an atom losing electrons is + charged -an atom gaining electrons is - charged -an atom that has lost/gained electrons is an ion example: NaCl

Fill in the chart below as practice for your quiz ElementSymbo l Atomic #Mass ## Protons# Neutrons # Electrons Atom or Ion? Potassium+1 ion I-1 ion 79Atom Phosphorus-3 ion

Chemical Bonds Covalent bond Covalent bond – bonding through the sharing of electrons -when covalently bonded – called a molecule -example: water

Chemical Bonds - when atoms share 2 electrons = single covalent bond - when atoms share 4 electrons = double covalent bond - when atoms share 6 electrons = triple covalent bond

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

Chemical Bonds Van der Waals Forces - When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules.

2-2 Properties of Water

The Water Molecule Polarity -oxygen has 8 protons in the nucleus so it has a stronger attraction for electrons than hydrogen protons do -causes water to be bent -causes water to have a slight negative charge on oxygen’s side; slight positive on hydrogen’s side -called polar = uneven distribution of electrons between the oxygen and hydrogen atoms

The Water Molecule Hydrogen Bonds - because of partial +/- charges of water, water molecules attract each other - cohesion – attraction between molecules of the same substance - not as strong as ionic and covalent bonds -water very cohesive - causes water to “bead”

The Water Molecule Hydrogen bonds - Adhesion – attraction between molecules of different substances -capillary action – forces that draws water up against gravity How does water move up a plant?

Solutions and Suspensions Mixture – material composed of two or more elements or compounds that are physically mixed together but not chemically combined Two types of mixtures can be made with water: - solutions-suspensions

Solutions - All the components of a solution are evenly distributed throughout the solution. - solute—the substance that is dissolved. - solvent—the substance in which the solute dissolves.

Solutions When a crystal of table salt is placed in warm water, sodium and chloride ions are attracted to the polar water molecules. Na + Cl - Water

Suspensions Suspension – Some materials do not dissolve when placed in water but separate into pieces so small that they do not settle out easily.

Acids, Bases and pH A water molecule is neutral, but can react to form hydrogen and hydroxide ions. H 2 O   H + + OH -

Acids, Bases, and pH The pH scale -Chemists devised a measurement system called the pH scale to indicate the concentration of H + ions in solution. The pH scale ranges from 0 to 14.

pH Scale At a pH of 7, the concentration of H + ions and OH - ions is equal.

Acids An acid is any compound that forms H + ions in solution.

Bases A base is a compound that produces hydroxide ions (OH - ions) in solution.

Buffers The pH of the fluids within most cells in the human body must generally be kept between 6.5 and 7.5. Controlling pH is important for maintaining homeostasis.

Question 1.Define the term “organic” in your own words. 2.What do you think someone would study if they study organic chemistry. 3.Write down what you know about carbohydrates, proteins, lipids and nucleic acids.

2-3 Carbon Compounds

The Chemistry of Carbon Organic means made of carbon Organic chemistry is the study of all compounds that contain bonds between carbon atoms.

Macromolecules Macromolecule = giant molecule Formed by polymerization – joining of smaller compounds to build a large one monomer – smaller compounds polymerpolymer – larger compounds made of monomers

Macromolecules 4 groups of macromolecule, organic compounds make up ALL living things: carbohydrates lipids nucleic acids proteins

Instructions: In this activity, you will work to become an expert on the basics of a type of biomolecule. Once assigned an expert group, you will join the others in that group to investigate your assigned category of biomolecules (see below). For your category, you will be looking to fully understand the follow about your group of molecules: What is the general formula for the group? What are the primary roles (functions) of these molecules in living organisms? What are the monomers and polymers of the group? How are the monomers bonded together? Be sure to include a diagram. Give the names of some specific examples of your group of molecules and include where they would be found. Once you have a good understanding of your group of biomolecules, you will meet back with your home group and teach them about your molecules.

Macromolecules Group NameChemical Composition ExamplesFunction in Living things Carbohydrates Lipids Nucleic Acids Proteins

Carbohydrates

Lipids

Proteins

Nucleic Acids

Organic Compounds Biology

2-4 Chemical Reactions and Enzymes

Chemical reactions A chemical reaction is a process that changes one set of chemicals into another set of chemicals. - sometimes slow processes, sometimes quick

The elements or compounds that enter into a chemical reaction are known as reactants. The elements or compounds produced by a chemical reaction are known as products. Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.

Energy in Reactions Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

When hydrogen gas reacts with oxygen to produce water vapor, it is an energy-releasing reaction in which energy is given off as heat. 2H 2 + O 2 2H 2 O How would you reverse this reaction?

Activation Energy Chemists call the energy that is needed to get a reaction started the activation energy.

Enzymes Some chemical reactions that make life possible are too slow or have activation energies. These chemical reactions are made possible by catalysts

Enzymes Enzymes speed up chemical reactions that take place in cells.

Regulation of Enzyme Activity Enzymes can be affected by any variable that influences a chemical reaction. 1. pH values 2. Changes in temperature