Chapter 2 Section 1

1. Chapter 2 Section 1 The Nature of Matter

2. The basic unit of matter is the atom - the subatomic particles that make up matter are protons, neutrons and electrons. • Protons have slightly positive charge (+) • Neutrons are neutral with no charge • Electrons have slightly negative charge (-) • Protons and Neutrons are found in the nucleus of an atom and have about the same mass • Electrons have a mass of about 1/1840 of a proton

3. Elements are pure substances made entirely of ONE type of atom found in nature Ex: H = hydrogen O = oxygen Na = sodium Fe = iron • Isotopes are atoms of the same element that differ in the # of neutrons - identified by their mass number - all isotopes of the same element have the same chemical properties

4. Isotope examples: The element CARBON Radioactive Carbon 14 6 electrons 6 protons 8 neutrons Carbon 12 6 electrons 6 protons 6 neutrons Carbon 13 6 electrons 6 protons 7 neutrons

5. A compound is a substance formed by the chemical combination of two or more elements Ex: Water (2:1 ratio) 2 hydrogens 1 oxygen NaCl (1:1 ratio) 1 sodium 1 chloride

6. Chemical Bonds • 2 main types of chemical bonds are ionic and covalent • Ionic bonding occurs when one or more electrons transfers from one atom to another - When an atom loses an electron, it becomes positively charged. - When an atom gains an electron, it becomes negatively charged. • Covalent bonding occurs when atoms share electrons

7. When atoms are joined together covalently, molecules are formed. - molecules are the smallest unit of a compound • Atoms of different elements attract electrons differently and therefore, van der Waals forces exist. - describes intermolecular forces of attraction - NOT as strong as ionic or covalent bonding - can hold larger molecules together Ex. A gecko climbing a vertical surface

8. Chapter 2 Section 2 Properties of H2O

9. Water molecules are neutral. They have 10 protons and 10 electrons. • A molecule of water has a bent shape. The hydrogen side has a slightly positive polarity. The oxygen side has a slightly negative polarity. - oxygen has 8 protons in its nucleus - hydrogen has 1 proton in its nucleus

10. A water molecule is polar because there is an uneven distribution of electrons between the oxygen atom & hydrogen atom. • Oxygen has a much stronger attraction to electrons than hydrogen. Thus, resulting in a polar molecule. - cohesion – attraction between molecules of the same substance Ex: H2O forms beads on surfaces, the molecules are drawn inward. - adhesion – attraction of molecules of different substances

11. Water is not always pure, it may be part of a mixture. • A mixture is material composed of two or more elements or compounds that are physically mixed, NOT chemically. Ex: sugar & sand salt & pepper • A solution has materials evenly distributed throughout. - solute – is dissolved - solvent – does the dissolving Ex. NaCl + H2O (solute) (solvent) ***WATER IS KNOWN AS THE UNIVERSAL SOLVENT***

12. A suspension is a mixture of H2O and undissolved particles Ex: blood • pH is a measure of the concentration of hydrogen in a solution (refer to page 43 in text) - The pH scale ranges from 0-14 - acids (0-6) high hydrogen ion concentration - bases (8-14) high hydroxide ion concentration - neutral (7) neutral concentration

13. Chapter 2 Sec 3 Carbon Compounds

14. The Chemistry of Carbon • We call the study of all compounds that contain bonds between carbon atoms, organic chemistry. • Carbon atoms have 4 valence electrons that may bond with another atom of a different element. • Carbon most commonly bonds with hydrogen, oxygen, phosphorus, and sulfur. • Carbon can also bond with other carbon atoms which allows them to form chains. • Carbon-carbon compounds can be single, double or triple covalent bonds. • Carbon is very versatile.

15. Macromolecules • Means “giant molecule” • Most molecules in living organisms are macromolecules. • Made from thousands to hundreds of thousands of smaller molecules. • Form by the process of polymerization, in which larger molecules are made by joining smaller molecules.

16. Smaller units (monomers) join together to form larger molecules (polymers). • The four groups of organic compounds (macromolecules) are: • Carbohydrates • Lipids • Nucleic acids • Proteins

17. Carbohydrates • Compounds made up of carbon, hydrogen and oxygen atoms (in a 1:2:1) • Living things use carbs as their main source of energy. • Plants and some animals use carbs for structural purposes. • Starches (complex carbs) and sugars are examples of carbs used by living things as a source of energy. • Sugars are monomers for a starch molecule.

18. Single sugar molecules are monosaccharides • Larger molecules formed from monosaccharides (galactose in milk, fructose and fruit) are polysaccharides (glycogen an animal starch)

19. Lipids • Not soluble in water • Made mostly from carbon and hydrogen atoms • Fats, oils and waxes • Lipids are used to store energy, parts of biological membranes and waterproof coverings • Steroids are lipids – used to carry chemical messages through the body • Saturated – when the fatty acid contains the maximum number of H atoms • Unsaturated – when there is at least one carbon-carbon double bond in the fatty acid

20. Nucleic Acids • Macromolecules containing hydrogen, oxygen, nitrogen, carbon and phosphorous. • They are polymers made of monomers called nucleotides • Nucleotides consist of a 5-carbon sugar, phosphate group and a nitrogenous base • Nucleotides join by covalent bonds to form a nucleic acid

21. Nucleic acids store or transmit heredity/genetic information. • Two kinds: • Ribonucleic acid (RNA) • Deoxyribonucleic acid (DNA) • RNA is a single sugar molecule (ribose) • DNA is a double sugar molecule (deoxyribose)

22. Proteins • Macromolecules that contain nitrogen, carbon, hydrogen and oxygen • Polymers of amino acids (amino acids folded into complex structures) • Amino acids are compounds with an amino group and a carboxyl group • More than 20 different amino acids are found in nature • Proteins control the rate of cell reactions • Some proteins form bone and muscle • Other proteins transport substances into and out of the cell

23. Proteins have up to 4 levels of organization: 1. sequence of amino acids 2. twisted or folded 3. chain is folded 4. Van der Waals forces to hold together

24. Chapter 2 Section 4 Chemical Reactions and Enzymes

25. A chemical reaction occurs when one set of chemicals is changed into another set of chemicals. • Chemical reactions always involve changes in chemical bonds. (breaking bonds and forming new bonds) • The elements or chemical components that ENTER into a chemical reaction are known as reactants. • The elements or chemical components that are PRODUCED in a chemical reaction are known as products.

26. All reactions use and produce energy. - Chemical reactions that release energy often occur spontaneously. - Chemical reactions that absorb energy need an energy source. - Activation energy is needed to get a reaction going. - A catalyst is something that speeds up a reaction (ex. Heat) - Enzymes are proteins that act as biological catalysts within cells. - Cells use enzymes to speed up chemical reactions. -Enzymes lower the activation energy needed for a reaction to begin.

27. Reactions and Energy • Endergonic Reactions: energy is taken in for the reaction to take place (energy is used) • Exergonic Reactions: energy is released

28. Enzyme Action • The reactants for an enzyme catalyzed reaction are called substrates • Enzymes are substrate specific: think of a lock and key • Once the enzyme binds to the active site of a substrate, an enzyme-substrate complex is formed • The reaction occurs, the products are released, and the enzyme changes back to its original conformation • E + S  E-S COMPLEX  E + P