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CHEMISTRY

CHEMISTRY. CHAPTER 2. THE NATURE OF MATTER ATOMS. Basic building blocks of matter. Cannot be broken down into simpler substances . 3 . 3 p articles make up atoms: a. Protons– positively charged b. Electrons- negatively charged c. Neutrons– neutrally charged. ELEMENTS AND ISOTOPES.

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CHEMISTRY

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  1. CHEMISTRY CHAPTER 2

  2. THE NATURE OF MATTERATOMS • Basic building blocks of matter. • Cannot be broken down into simpler substances. 3 . 3 particles make up atoms: a. Protons– positively charged b. Electrons- negatively charged c. Neutrons– neutrally charged

  3. ELEMENTS AND ISOTOPES 1. Isotopes a. Elements which differ in the number of neutrons in the nucleus. 2. Radioactive Isotopes a. Unstable & the nucleus breaks down at a steady rate and releases “radioactivity”. • Chemical Compounds a. Formed by the combining of two or more elements.

  4. ELEMENTS 6 C 12.011 Atomic number - # of protons in the nucleus Element symbol Atomic mass Element - Carbon

  5. ISOTOPES NON-RADIOACTIVE CARBON-12 NON-RADIOACTIVE CARBON -13 RADIOACTIVE CARBON -14 6 electrons 6 protons 6 NEUTRONS 6 electrons 6 protons 7 NEUTRONS 6 electrons 6 protons 8 NEUTRONS Fig. 2.2 – Isotopes of Carbon – pg. 37 – Because they have the same number of electrons, these isotopes of carbon have the same chemical properties. The difference among the isotopes is the number of neutrons in their nuclei.

  6. Chemical Bonds • Created when electrons of elements interact. Electrons involved in bonding are located on the outside of an atom – called the “valence electrons.” • 2 kinds of bonds: • Ionic • Covalent

  7. Ionic Bonds • Chemical compound created when one element donates electrons and one element accepts electrons. • Example: NaCl – Sodium (Na) (donor) Chloride (Cl) (acceptor) – salt

  8. IONIC BOND - EXAMPLE Sodium (Na) Chlorine (Cl) Sodium Ion (Na+) Chlorine ion (Cl-) Tranfer of e- Protons +11 Protons +17 Protons +11 Protons +17 Electrons -11Electrons -17Electrons -10 Electrons -18 Charge 0 Charge 0 Charge +1 Charge -1 Fig. 2.3 – pg. 38 – The chemical bonds in which electrons are transferred from one atom to another is called an IONIC BOND. The compound sodium chloride forms when sodium loses its valence electron to chlorine.

  9. THE IONIC BOND

  10. Covalent Bonds • Bond created when elements share their valence electrons (the outside e-) • Makes a “molecule” • Example: H2O – water (two hydrogens & 1 oxygen) Fig. 2-4 – Page 38 – The chemical bond in which electrons are shared between atoms is called a covalent bond. In a wter molecule, each hydrogen atom shares two electrons with the oxygen atom.

  11. THE COVALENT BOND

  12. The Water Molecule • Chemical Formula – H2O • Hydrogen Bonds • holds water molecules together

  13. Solutions Solutions – mixture of 2 or more substances where the molecules evenly distributed. a. solvent – part of a solution which does the dissolving. (1) example: Water (universal solvent) b. solute – particles which are dissolved to make a solution (1) example: Salt

  14. Cl- Cl- Na+ Na+ H2O Water FIG 2-9 – Page 42 – When an ionic compound such as sodium chloride (salt) are placed in water, water molcules surround and separate the positive (Na+) & negative (Cl-) ions.

  15. Suspensions • Suspensions – materials that do not completely dissolve in H2O, • Are so small they don’t settle to the bottom. • Movement of the H2O keeps these particles “suspended”. • Example: Blood has particles like cells that remain in suspension.

  16. Acids, Bases, and pH • The pH Scale • pH – concentration (how much ) of H+ (hydrogen ions) present in a solution • Acids – any substance which releases H+ in water. • pH is 0 – 6.9 on the pH scale. • Bases – any substance which release OH- (hydroxide ions) in water. • pH is 7.1 – 13.0 on pH scale. • Neutral – any substance with a pH of 7.0 • Buffers – substances which are used to keep a steady pH.

  17. THE pH SCALE Oven cleaner Bleach • Increasing basicity • Bases have pH of 7.1 - 14 Ammonia solution Soap Sea water Human blood • Neutral pH = 7.0 Pure water Milk Normal rainfall Acid rain • Increasing Acidity • Acids have a pH of 0-6.9 Tomato juice Lemon juice Stomach acid FIG. 2-10- PAGE 43 – The concentration of H+ ions determines whether solutions are acidic or basic. The most acidic on this pH scale is stomach acid & the most basic on this scale is oven cleaner

  18. ADHESION & COHESION ADHESION – The attraction between DIFFERENT substances. ex. – water and glass – this forms the meniscus COHESION – The attraction between the same substances. ex. – water molecules

  19. The Chemistry of Carbon Macromolecules 1. “giant molecules” 2. Made by putting many molecules together 3. Monomer – small molecules like glucose a. Put together to make long chains of molecules (polymer) like carbohydrates. 4. Carbohydrate is a polymer of glucose.

  20. MONOMER & POLYMER Starch is a polymer of glucose Glucose is a monomer

  21. ORGANIC CHEMISTRY • Organic Molecules – Carbon containing molecules. 4 types of Organic compounds 1. Carbohydrates 2. Lipids 3. Nucleic Acids 4. Proteins

  22. Carbohydrates • Made up of carbon, hydrogen & oxygen atoms. • Main source of energy for many living organisms • Example: starch

  23. Starch Figure 2-13: Page 45 – Starches & sugars are examples of carbohydrates that are used by living things as a source of energy. Starch is a polymer of the monomer glucose.

  24. Lipids (fats) • Made up of carbon & hydrogen atoms • Stored by cells for future energy needs. • Important for cushioning organs • Important part of the cell membrane

  25. Fig. 1-14 – Page 46 - Lipids are used to store energy. Lipid moleucles are made up of fatty acids & glycerol.

  26. Nucleic Acids • Contain hydrogen, oxygen, nitrogen, carbon & phosphorus. • DNA – deoxyribonucleic acid – contains the genetic information. • RNA – ribonucleic acid – contains the “code” to make proteins & enzymes. • Parts • sugar (ribose in RNA & deoxyribose in DNA) • nitrogen base • phosphate backbone

  27. Proteins • Made up of amino acids “polymers of amino acids” • 20 amino acids. • also called polypepetides • Contain carbon, hydrogen, nitrogen & oxygen. 4 Functions of proteins 1. Control the rate of reactions – done by enzymes 2. Form bones & muscle 3. Form the immune system 4. Transports substances into and out of cells.

  28. AMINO ACIDS Amino group Carboxyl group General Structure Alanine Serine Fig. 2-16 – Page 47 – Amino acids are the monomers of proteins. All amino acids have an amino group at one end and a carboxyl group at theother end. What makes one amino acid different from the other is the “R-group” section of the molecule.

  29. Chemical Reactions and Enzymes • Chemical Reactions • Change one set of chemicals into another. • Involves the breaking of bonds and the formation of new bonds. • Energy in Reactions • Activation Energy - Energy needed to start a reaction • Enzymes • Proteins • Catalysts for reactions – Speed up reactions in cells.

  30. ENERGY IN REACTIONS Products Activation energy Activation energy Reactants Reactants Products Fig. 2-19 – Page 50 – Chemical reactions that release energy often occur spontaneously. Chemical Reactions that absorb energy will occur only with a source of energy.

  31. Reaction of Sodium & Cholorine

  32. Enzyme Action • The Enzyme-Substrate Complex • a. When an enzyme binds to the substance (substrate) it needs to break down. • Regulation of Enzyme Activity • a Temperature, amount of substrate available and amount of enzyme all affect the rate of the reaction

  33. Enzyme Action Reaction pathway without enzyme Activation energy without enzyme Reactants Activation energy with enzyme Reaction pathway with enzyme Products Fig. 2-20 – Page 51 – Enzymes speed up chemical reactions thattake place in cells. Notice how the addition of an enzyme lowers the activation energy in this reactions. This action “speeds” up the reaction.

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