Transcript Chapter 6
Chemistry in Biology Chapter Six Essential Questions • • • • What are atoms? How are the particles that make up atoms diagrammed? What are the similarities between covalent and ionic bonds? How are van der Waals forces described? Vocabulary Review New continued • • • • • • • • substance New • • • • • • atom nucleus proton neutron electron element isotope compound covalent bond molecule ion ionic bond van der Waals force Atoms The structure of an atom • Atoms are the building blocks of matter. • Atoms are made up of smaller particles called neutrons, protons, and electrons • Protons are positively charged particles (p+). • Neutrons are particles that have no charge (n0). • Electrons are negatively charged particles (e-). Atoms The structure of an atom • Protons and neutrons are located in the center of the atom, called the nucleus. • Electrons are located outside the nucleus. Atomic Structure- Movie Clip https://www.youtube.com/watch?v=R1RMV5qhwyE (Take Notes on movie here) Elements • An element is a pure substance that cannot be broken down into other substances by physical or chemical means. • There are over 100 known elements, 92 of which occur naturally. • Each element has a unique name and symbol. Elements The periodic table of elements • Horizontal rows are called periods, vertical columns are called groups. Elements Isotopes • Atoms of the same element that have the same number of protons and electrons but have a different number of neutrons are called isotopes. Elements Radioactive isotopes • Changing the number of neutrons in an atom does not affect the charge, but does affect the stability. • When a nucleus breaks apart, it gives off radiation that can be detected and used for many applications. • Isotopes that give off radiation are called radioactive isotopes. Isotopes- Movie Clip (Take Notes here) https://www.youtube.com/watch?v=IsJx5jD6ctY Compounds • A compound is a pure substance formed when two or more different elements combine. • Compounds are always formed from a specific combination of elements in a fixed ratio. • Compounds cannot be broken down into simpler compounds or elements by physical means, but can be broken down by chemical means. Chemical Bonds • The force that holds substances together is called a chemical bond. • The electrons of an atom are responsible for forming chemical bonds. • Electrons travel around the nucleus of an atom in areas called energy levels. • Atoms become more stable by losing electrons or attracting electrons from other atoms. Chemical Bonds Covalent bonds • The chemical bond that forms when electrons are shared is called a covalent bond. • A molecule is a compound in which the atoms are held together by covalent bonds. Chemical Bonds Ionic Bonds • An atom that has lost or gained one or more electrons is an ion. • Ions carry an electric charge. • An ionic bond is an electrical attraction between two oppositely charged atoms. Ionic and Covalent Bonds- Movie Clip (Take Notes here) https://www.youtube.com/watch?v=OTgpN62ou24 Chemical Bonds Ionic bonds • Some atoms tend to donate or accept electrons more easily than other atoms. • The elements identified as metals tend to donate electrons. • The elements identified as nonmetals tend to accept electrons. • Most ionic compounds dissolve in water, are crystalline at room temperature, and have higher melting points than compounds formed by covalent bonds. van der Waals Forces • Attractions between molecules are called van der Waals forces. • When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together. • The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons. van der Waals Forces van der Waals forces in water • The slightly positive and slightly negative charges around the water molecule are attracted to the opposite charge of other nearby water molecules. • van der Waals forces are responsible for water droplet formation and surface tension. Review Essential Questions • • • • What are atoms? How are the particles that make up atoms diagrammed? What are the similarities between covalent and ionic bonds? How are van der Waals forces described? Vocabulary • • • • • atom nucleus proton neutron electron • • • • • element isotope compound covalent bond molecule • • • ion ionic bond van der Waals force Essential Questions • • • What are the parts of a chemical reaction? How can energy changes be related to chemical reactions? What is the importance of enzymes in living organisms? Vocabulary Review New • process • • • • chemical reaction reactant product activation energy • • • • catalyst enzyme substrate active site Reactants and Products • A chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances. • Chemical bonds are broken or formed during a chemical reaction. • Clues that a chemical reaction has taken place: • production of heat or light • formation of a new gas, liquid, or solid • Substances can also undergo physical changes, which change the appearance but not the composition. Reactants and Products Chemical equations • In written chemical equations, chemical formulas describe the substances in the reaction and arrows indicate the process of change. • Reactants are the starting substances, on the left side of the arrow. • Products are the substances formed during the reaction, on the right side of the arrow. • The arrow can be read as “yields” or “react to form.” Reactants and Products Chemical equations • Balanced equations • In chemical reactions, matter cannot be created or destroyed. • All chemical equations must show this balance of mass. • The number of atoms of each elements on the reactant side must equal the number of atoms of the same element on the product side. C6H12O6 + 6O2 6CO2 + 6H2O Energy of Reactions Activation energy • The minimum amount of energy needed for reactants to form products is called activation energy. • Some reactions rarely happen due to the high activation energy required. Energy of Reactions Energy change in chemical reactions • Reactions that release energy in the form of heat are exothermic. • Reactions that absorb energy in the form of heat are endothermic. Enzymes • All living things are driven by chemical reactions. • Additional substances are needed to reduce activation energy and reaction time in living organisms. • A catalyst is a substance that lowers the activation energy needed to start a chemical reaction. • Catalysts do not change the amount of product produced, nor are they used up during the reaction. Anabolic Reactions- Catabolic Reactions- Enzymes • Special proteins called enzymes are the biological catalysts that speed up the rate of chemical reactions in biological processes. • Most enzymes are specific to one reaction. Enzymes • The reactants that bind to an enzyme are called substrates. • The specific location where a substrate binds on an enzyme is called the active site. • Factors such as pH, temperature, and other substances affect enzyme activity. Review Essential Questions • • • What are the parts of a chemical reaction? How can energy changes be related to chemical reactions? What is the importance of enzymes in living organisms? Vocabulary • • • chemical reaction reactant product • • • activation energy catalyst enzyme • • substrate active site Essential Questions • • • How does the structure of water make it a good solvent? What are the similarities and differences between solutions and suspensions? What are the differences between acids and bases? Vocabulary Review New • • • • • • • • • • • physical property polar molecule hydrogen bond mixture solution solvent solute acid base pH buffer Water’s Polarity • Water molecules are formed by covalent bonds that link two hydrogen (H) atoms to one oxygen (O) atom. • Water molecules have a slightly positive end near the H atoms and a slightly negative end near the O atom. • Molecules that have an uneven distribution of charge are called polar molecules, meaning they have oppositely charged regions. Water’s Polarity • When a charged region of a polar molecule comes close to the oppositely charged region of another polar molecule, a weak attraction forms. • A hydrogen bond is a weak interaction involving a hydrogen atom and a fluorine, oxygen, or nitrogen atom. • A hydrogen bond is a strong type of van der Waals force. Visualizing Properties of Water- Movie Clip (Take Notes Here) https://www.youtube.com/watch?v=3jwAGWky98c Mixtures with Water • A mixture is a combination of two or more substances in which each substance retains its individual characteristics and properties. • Mixtures are either homogeneous or heterogeneous. Mixtures with Water Homogeneous mixtures • When a mixture has a uniform composition throughout, it is called homogenous. • A solution is another name for a homogeneous mixture. • In a solution, there are two components: • A solvent is a substance in which another substance is dissolved. • A solute is the substance that is dissolved in the solvent. Mixtures with Water Heterogeneous mixtures • When the components in a mixture remain distinct, it is a heterogeneous mixture. • A suspension is a type of heterogeneous mixture where the particles settle out over time • A colloid is a heterogeneous mixture in which the particles do not settle out. Mixtures with Water Acids and bases • Many solutes readily dissolve in water because of water’s polarity. • Substances that release H+ when they are dissolved in water are called acids. • Substances that release hydroxide ions (OH−) when they are dissolved in water are called bases. Mixtures with Water pH and buffers • The amount of hydrogen or hydroxide ions in a solution determines the strength of an acid or base. • The measure of concentration of H+ in a solution is called pH. • Acids have pH values < 7; bases have pH values > 7 • Buffers are mixtures that can react with acids or bases to keep the pH within a particular range. Review Essential Questions • • • How does the structure of water make it a good solvent? What are the similarities and differences between solutions and suspensions? What are the differences between acids and bases? Vocabulary • • • • polar molecule hydrogen bond mixture solution • • • solvent solute acid • • • base pH buffer Essential Questions • • • What is the role of carbon in living organisms? What are the four major families of biological macromolecules? What are the functions of each group of biological macromolecules? Vocabulary Review New • • • • • • • • • organic compound macromolecule polymer carbohydrate lipid protein amino acid nucleic acid nucleotide Organic Chemistry • Organic chemistry is the study of organic compounds – compounds that contain carbon. • Carbon is a component of almost all biological molecules. • Carbon atoms bond together to form a variety of important organic compounds. Macromolecules • Macromolecules are large molecules that are formed by joining smaller organic molecules together. • Polymers are molecules made from repeating units of identical or nearly identical compounds called monomers. • Macromolecules are organized into four major categories: • Carbohydrates • Lipids • Proteins • Nucleic acids Biological Macromolecules – Movie Clip (Take Notes Here) https://www.youtube.com/watch?v=YO244P1e9QM Macromolecules Carbohydrates • Compounds composed of a ratio of 1 carbon :2 hydrogen :1 oxygen are called carbohydrates. • Carbohydrates have a general formula of (CH2O)n where n indicates the number of CH2O units in the chain. • Carbohydrates are a central energy source in organisms, as well as functioning as cellular support in plants, fungi, and animals. Macromolecules Lipids • Lipids are molecules made mostly of carbon and hydrogen that make up the fats, oils, and waxes. • A lipid’s primary function is to store energy, but they are also used to prevent water loss in plants and form the honeycomb in beehives. Macromolecules Proteins • Proteins are compounds made of smaller carbon compounds called amino acids. • All amino acids are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur and share the same general structure. Macromolecules Proteins • There are 20 different amino acids, and proteins are composed of various combinations • Proteins are responsible for structural support in cells, transporting substances within and between cells, signaling within and between cells, speeding up chemical reactions, and controlling cell growth. Peptide Bonds- Movie Clip (Take Notes Here) https://www.youtube.com/watch?v=cgf1l3YQPXo https://www.youtube.com/watch?v=2Jgb_DpaQhM Macromolecules Nucleic acids • Nucleic acids are complex macromolecules that transmit and store genetic information. • Nucleic acids are composed of smaller repeating subunits composed of carbon, nitrogen, oxygen, phosphorus, and hydrogen called nucleotides. Macromolecules Nucleic acids • There are two types of nucleic acids in living organisms: • Deoxyribonucleic acid (DNA) • Ribonucleic acid (RNA) Review Essential Questions • • • What is the role of carbon in living organisms? What are the four major families of biological macromolecules? What are the functions of each group of biological macromolecules? Vocabulary • • • macromolecule polymer carbohydrate • • • lipid protein amino acid • • nucleic acid nucleotide