Chapter Two: Matter

1. Chapter Two: Matter

2. Matter • Atom-basic unit of matter • 1. Subatomic particles- protons, neutrons, electrons • A. Protons- positive charge, center of atom (nucleus) • B. Neutron- neutral, center of atom • C. Electrons- negative charge, in constant motion around nucleus

3. Matter • Elements- pure substance that consists entirely of one type of atom • 1. Represented by symbol • 2. Atomic number- number of protons in an atom • Number of protons = number of electrons • 3. Atomic mass- protons and neutrons • A. Number of neutrons = atomic mass – atomic number

4. Matter • 4. Electron Cloud- area around nucleus where electrons are orbiting • 1st level- holds 2 electrons • 2nd level- holds 8 electrons • 3rd level- holds 8 electrons • 4th level- holds 18 electrons

5. Example • 17 atomic number Cl symbol 35.453 mass number • Atomic number: • Atomic mass: • Number of protons: • Number of neutrons: • Number of electrons:

6. Isotopes- atoms that have an equal number of protons but different number of neutrons • Radioactive isotopes- nuclei are unstable and break down at a constant rate over time • Geologists determine age of rocks and fossils by analyzing the isotopes in them • Radiation from some isotopes are used to treat cancer • Used as tracers

7. Compounds- substance formed by the chemical combination of two or more elements in definite proportions • Example – H2O • Chemical Bonds • Valence electrons- electrons that are available to form bonds • Ionic bonds- when one or more electrons are transferred from one atom to another • Example- NaCl

8. Covalent bond- forms when electrons are shared between atoms • Example- H2O • Ions- positive or negative charged atom • Positive charge= lose an electron • Negative charge = gain an electron • Molecules- the smallest unit of most compounds, the structure that results when atoms are joined together by covalent bonds • Subscript- number of atoms • Coefficient- number of molecules of a compound element number of atoms • H2O • 2H2O2

9. Van der Waals Foreces- when molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules • Example: Geckos • Physical Changes: change in form of substance not the chemical makeup • Ex: size, shape, states of matter

10. Chemical changes- a substance changes into a new substance • Example: rusting, digesting, rotting

11. Properties of Water • Most abundant compound in living things • Covers ¾ ‘s of Earth’s surface • Expands when it freezes so ice is less dense than liquid water • Water molecule- neutral • 1. polarity- an uneven sharing of electrons between the O and H atoms • Example: DRAW A WATER MOLECULE

12. 3. Hydrogen bonds • Water can have as many as four H bonds at the same time • A. cohesion- attraction between molecules of same substance • Surface tension- the force that occurs because of cohesion • Example- insect walk on water, drops of water form beads on smooth surface • B. adhesion- attraction between molecules of different substances • Example- meniscus- the adhesion between water molecules and graduated cylinder are stronger than the cohesion between water molecules • 1. Capillary action- adhesion causes H20 to rise in a narrow tube • A. Example- draw H20 out of roots of plant and up into the stem and leaf

14. B. Solutions and Suspensions • 1. Mixture- a material composed of two or more elements or compounds that are physically mixed together but not chemically combined • Example- salt and pepper, sugar water • A. Solution-mixture of two or more substances in which the molecules of the substances are evenly distributed • 1. Example- Salt water • Solute- the substance that is dissolved (salt) • Solvent- the substance in which the solute is dissolved (water) • H2O- the greatest solvent of Earth • B. Suspensions- mixture of water and undissolved materials

15. C. Acids, Bases, pH • 1. pH scale- indicates the concentration of H ions in solution • A. 0-14 • pH 7 = neutral, concentration of H ions and OH ions are equal • Example- pure water • pH below 7= acidic, more H ions than OH ions • pH above 7= basic, more OH ions than H ions Basic

16. C. Acids, Bases, pH • 2. Acids- a compound that forms H ions in solution pH of 1-3 = strong acid • Example- HCl • 3. Bases- compound that produces hydroxide (OH) pH of 11-14 = strong base • Example- lye , NaOH

17. III. Carbon Compounds • Organic Chemistry- study of all compounds that contain bonds between carbon atoms • A. Chemistry of carbon • 1. carbon atoms can bond to other carbon atoms to form very long chains • B. Macromolecules- very large molecules • 1. monomers- smaller unit that can join together with other small units to form polymers • 2. polymers- large compound formed from combinations of many monomers

18. 3. Dehydration synthesis • The formation of a chemical bond by removing a water molecule

19. 4 types of macromolecules: • Carbohydrates • Lipids • Nucleic acids • Protein

20. Carbohydrates: • compounds made up of C, H, O atoms in a 1:2:1 ratio • A. living things use carbohydrates as their main source of energy • B. living things store extra sugar as starch (long chains of sugar molecules ) • C. monosaccharides- single sugar molecules • Ex: glucose, galactose (milk), fructose (fruit) • Disaccharides- sugars made up of two covalently bonded monosaccharides • Ex: sucrose (table sugar), lactose (milk sugar) • D. polysaccharides- large macromolecules formed from monosaccharides • Example: glycogen (animal starch), causes muscle contractions • Example: cellulose- tough fibers that give plants much of their strength and rigidity. Major component of wood and paper

21. 2. Lipids • Macromolecules made mostly of carbon and hydrogen atoms and are not soluable in H2O • A. stores energy, waterproof coverings, steroids • B. example- fats, oils, waxes • 2 types: • 1. saturated- solid at room temp • Example: butter • 2. unsaturated- liquid at room temp • Example: olive oil

22. 3. Nucleic Acids • Macromolecules that contain H, O, N, C, and P which are formed from Nucleotides (Page 47) • A. nucleotide (monomer)- consists of sugar, phosphate, nitrogen base • B. Store and transmit genetic info • C. 2 kinds- • DNA – deoxyribose nucleic acid sugar = deoxyribose • RNA- ribonucleic acid sugar = ribose

23. 4. Protein • Polymers of amino acids which are made of N, C, H, O. They control rate of reactions, build bones and muscles • A. 20 different amino acids • B. instructions for arranging amino acids into different proteins which are stored in DNA • C. each protein has a specific role • D. have an amino group (-NH2) on one end, a carboxyl group (-COOH) on the other end and an R group. The R group makes proteins different.

24. IV. Chemical Reactions and Enzymes • A. Chemical reactions- process that changes one set of chemicals into another • Example: Iron (Fe) + O rust • H+ O H2O • Reactants- what you start with • Products- what’s produced Subscript

25. B. Energy Changes • 1. Chemical reactions release energy- exothermic • A. occur spontaneously • B. energy released in form of heat • 2. Chemical reactions that absorb energy- Endothermic • A. will not occur without a source of energy • B. in plants, the energy comes from sun in animals, the energy comes from food

26. Activation Energy and Catalysts • C. Activation Energy -the energy needed to get a reaction started • D. Catalysts- substance that speeds up the rate of a chemical reaction • 1. Catalysts lower a reaction’s activation energy • Enzymes- proteins that act as biological catalysts to speed up chemical reactions in cells • A. substrate- reactant of an enzyme- catalyzed reaction • B. Substrates bind to a site on the enzyme called the active site • C. Enzyme-Substrate Complex- the enzyme and substrate comes together to form this • D. “Lock and Key” model- the fit of the enzyme and the substrate is so precise that the fit is often referred to as this