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Symbols

Symbols. Symbols. Atomic Number- No. of protons Atomic Mass – No. of protons and neutrons (electron mass negligible) Chemical symbols found on Periodic table. Definitions. Element - Substance consisting of one type of atom. Isotope – Atom of an element with different number of neutrons.

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Symbols

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  1. Symbols

  2. Symbols Atomic Number- No. of protons Atomic Mass – No. of protons and neutrons (electron mass negligible) Chemical symbols found on Periodic table

  3. Definitions • Element- Substance consisting of one type of atom. • Isotope – Atom of an element with different number of neutrons. • Molecule – Smallest unit of substance. Retains chemical & physical properties of substance. Compose of 2 atoms held together by a bond. Atoms may be of same/different elements. • Compound- Substance composed by chemical combination of two or more elements in definite proportions.

  4. Relationships • Work in groups of 4 and respond to the following questions. • Are N2, H2, and O2 elements or compounds? • Are N2, H2, and O2 atoms or elements? • Is C an atom or element? • Is H20 a molecule or a compound?

  5. Elements of Life

  6. Organic Compounds • Carbohydrates (sugars) : Carbon, Oxygen, Hydrogen • Lipids (fats): Carbon, Oxygen, Hydrogen, and Phosphorus • Proteins: Carbon, Oxygen, Hydrogen, Nitrogen, and Sulfur • Nucleic Acids (DNA, RNA): Carbon, Oxygen, Hydrogen, Nitrogen, Phosphorus

  7. Isotopes have a different # of neutrons.Isotopes have the same number of electrons and behave the same way chemically.

  8. Radioisotopes • Valuable research tools. • Unstable nucleus; over time gives off subatomic particles & energy; results in stable nucleus. • Decay of radioisotopes occurs at constant rate called half life. • Use carbon isotopes to date fossils and minerals. • Use other radioisotopes in medical tests.

  9. Isotopes Why is the atomic mass not exactly double the atomic number?

  10. Periodic Table

  11. Bonding • Atoms – held together by chemical bonds. • Two types – Ionic bond and covalent bond. • Ionic bond – one or more electrons transferred from one atom to another. • Covalent bond – electrons shared between atoms. • Van der Waals Forces –Weak attractive force between molecules.

  12. Bonding • Compounds are held together by chemical bonds. • Electrons are involved in chemical bonding. • The outer shell (orbital) of atom is called valence shell. • Electrons in this shell are valence electrons.

  13. Bonding • Atoms with unfilled valence shells are chemically reactive. • Atoms seek to fill valence shell. • Bonding fills valence shell with electrons.

  14. Ionic Bond

  15. Covalent Bond

  16. Bond Strength • Covalent bonds are strongest bond. Takes more energy to break bond. • Ionic bonds are weaker than covalent. • Van der Waals forces are weak attractions. Assignment: Create a graphic organizer. Compare and contrast ionic and covalent bonds. Work with a partner.

  17. Properties of Water • Only substance on Earth found as solid, liquid, and gas. Solid less dense than liquid state. • Polarity • Cohesion • Adhesion • Capillary Action

  18. Polarity Water is polar- uneven distribution of electrons between hydrogen and oxygen atoms. Hydrogen bonds- Attraction between + charged H and – charged O. One atom forms multiple H bonds. H bonds give water special properties.

  19. Cohesion • Attraction between molecules of the same substance. • Surface tension – tension at surface of water is related to cohesion

  20. Adhesion • Attraction between molecules of different substances.

  21. Capillary Action Capillary action is responsible for water moving through a plant. Adhesion- water is attracted to roots, stems, and leaves. Cohesion – water column is held together as it rises.

  22. Review What do the numbers 11 and 23 near the sodium symbol represent? Use the Bohr model on the right. How many a. How many valence electrons are available? b. What is the atomic mass of this element? c. Is this element an isotope? Why? What elements are present in a protein? What type of bond is occurring between the Mg and Cl? a. Which of the two elements has a higher electro-negativity? b. What would happen to this compound in an aqueous solution? 5. On the left is a drop of water. Why does water make drops?

  23. Mixture/Solutions/Suspensions • Mixture: Two or more elements/compounds physically mixed but not chemically mixed. • Solution: Homogeneous mixture in which one substance is dissolved (solute) in another (solvent) usually water. • Suspension: Mixture of water and non dissolved substance.

  24. Solution • NaCl dissolves in water. • NaCl is the solute; water is the solvent. • Water surrounds the Na + and Cl-.

  25. Suspensions • Blood is an example of a suspension. • Red blood cells are suspended in a liquid called plasma.

  26. pH • A molecule of water can form ions • 1 molecule in 550 million will react to form ions. • Water has the same number of H+ and OH-; it is neutral. • Solutions that have a higher concentration of H+ than water are acidic. • Solutions that have a lower concentration of H+ that water are basic (or greater OH -)

  27. pH Scale 7 = Neutral pH Below 7 = acidic pH Above 7 = basic pH Each pH change represents a 10 fold change in the level of H+. EX: pH of 4 has 10x more H+ than pH of 5 EX: pH of 5 has 10x less H+ than pH of 4

  28. Organic Molecules • Are made of carbon. • Can be very small like CO2 to very large like a protein. • Living organisms are made of and use organic molecules.

  29. Carbon • Is tetravalent; can form 4 bonds. • Bonds with many types of elements: H,N,O,P,S • Can form many types of structures.

  30. Macromolecules • Macromolecule – Giant molecule made from smaller molecules. • Polymer- Large molecule consisting of similar or identical molecules linked together. • Monomer – Subunit of polymer. • Polymerization - Process of polymer creation

  31. Polymerization

  32. Figure 5.2 The synthesis and breakdown of polymers

  33. Organic Molecules • Carbohydrates, proteins, and nucleic acids are polymers (and macromolecules). • Lipids are macromolecules (but not polymers) • All are biomolecules.

  34. Carbohydrates • Made of C, H, O in 1:2:1 ratio; (CH2O) • Used for energy by all organisms, plants & some animals use them for structures. • Monosaccharides- single sugar (monomer) • Glucose is a monosaccharide used for energy.

  35. Carbohydrates • Disaccharides - Two sugars • Table sugar sucrose is a disaccharide composed of two monosaccharides glucose and fructose (fruit sugar).

  36. Carbohydrates • Polysaccharides are polymers made of many monosaccharides. • Examples: - Plant starch – used to store energy - Glycogen (animal starch) – used to strore energy. - Cellulose – used by plants for structure. Cellulose

  37. Lipids • Made from C, H mostly. • Used to store energy, for cell membranes, water proof coverings, some hormones. • Three types of lipids - Triglycerides - Phospholipids - Cholesterol

  38. Triglycerides • Made of 2 components - glycerol - fatty acid chains (3) • Used to store energy (2x energy in a polysaccharide)

  39. Saturated vs. Unsaturated • Saturated Lipid- • Single bonds between Cs in carbon skeleton. • Each C single bonded to H. (i.e. saturated with H) • Chain straight / pack tightly /solids at RT. • Unsaturated Lipid – • Some Cs double bonded • Makes kink in chain • Chains can’t pack as tightly/ oils at RT.

  40. Figure 5.11 Examples of saturated and unsaturated fats and fatty acids 

  41. Saturated vs. Unsaturated • Saturated fats - Animal fats - Raise LDL or bad cholesterol levels. • Unsaturated fats -Vegetable fats - either help to raise HDL or good cholesterol levels or decrease LDL levels.

  42. Phospholipids • Phospholipids- glycerol, • 2 fatty acid chains, & phosphate group. • Function – to make up cell membranes.

  43. Cholesterol • Steroids- lipids with 4 fused carbon rings. • Cholesterol is a steroid. • Function- component of animal cell membranes. • Precursor from which other steroids are made including hormones. • High levels contribute to atherosclerosis

  44. Nucleic Acids • Made of C, H, O, N, P • Used to store and transmit genetic information. • Two types: DNA & RNA • Monomer: Nucleotide

  45. Nucleotides • Nucleotides • Nitrogenous base • Pentose (5C) sugar/ Deoxyribose in DNA • Ribose in RNA -Phosphate group

  46. DNA DNA (polymer) is made by bonding nucleotides together. Phosphate of one nucleotide is bonded to sugar of the next nucleotide.

  47. Proteins • Made of C, H, O, N • Have many functions: - Control chemical reaction rates – Enzymes - Form bones and muscles – Structural - Hemoglobin carries oxygen – Transport - Fight disease - Antibodies

  48. Proteins • Are structurally diverse consistent with their many functions.

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