How to access School Files

1. How to access School Files • 1) Google “ocdsb” • 2) Go to the students drop down menu and select “My Docs-Active Directory” • 3) Enter student number and password • 4) Then choose: Data 1 on “ADLTFS1.ad.osdsb.ca”(X:) • 5) Click on “Handout” • 6) Scroll down and click “SBI4U”

2. Atoms, elements, compounds, & molecules How molecules interact Water is essential for life pH and buffers The Chemical Basis of Life 0

3. ELEMENTS, ATOMS, AND MOLECULES 0 • Living organisms are composed of matter • Matter has mass and occupies space • Atom: A unit of matter, the smallest unit of an element.

4. Element: A substance composed of atoms having an identical number of protons in each nucleus. Elements cannot be reduced to simpler substances by normal chemical means. • Living organisms are composed of about 25 chemical elements • Trace elements • Are essential to life, but occur in minute amounts

5. Carbon, hydrogen, oxygen, and nitrogenMake up the bulk of living matter 0

6. 0 • Trace elements are common additives to food and water • Dietary deficiencies in trace elements can cause various physiological conditions

7. Sodium Chloride Chlorine Sodium 0 • Elements can combine to form compounds • Chemical elements • Combine in fixed ratios to form compounds

8. Atoms consist of protons, neutrons, and electrons • Atom: The smallest particle of matter that still retains the properties of an element 0 • Subatomic Particles • An atom is made up of protons, neutrons and electrons • The nucleus contains neutrons and protons and is surrounded by electrons Electron cloud – – 2e– + + + + Nucleus + Protons 2 Massnumber = 4 Neutrons 2 – Electrons 2

9. 0 • Differences in Elements • Atoms of each element are distinguished by a specific number of protons 0 Electroncloud 6e– + Massnumber = 12 + Nucleus + Protons 6 Neutrons 6 6 6 Electrons

10. 0 • Isotopes • The number of neutrons in an atom may vary • Variant forms of an element are called isotopes • Some isotopes are radioactive Table 2.4 • Radioactive isotopes are useful as tracers for monitoring the fate of atoms in living organisms • The half-life of a radioisotope is the time required for half of the atoms in a sample to decay

11. During beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron and an antineutrino.

12. Research • Biologists often use radioactive tracers to follow molecules as they undergo chemical changes in an organism 0 • Medical Diagnosis • Radioactive tracers are often used for diagnosis - In combination with sophisticated imaging instruments

13. How brain function is studied PET, CAT, MRI, etc. Hearing, speaking, seeing, thinking about words Music Appreciation

14. PET • Positron emission tomography (PET) is a nuclear medicine imaging technique which produces a three-dimensional image or picture of functional processes in the body. • The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule

15. PET Scan

16. CT • Computed tomography (CT) is a medical imaging method employing tomography created by computer processing. • Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation

17. MRI • Magnetic resonance imaging (MRI), or nuclear magnetic resonance imaging (NMRI), is primarily a noninvasive medical imaging technique used in radiology to visualize detailed internal structure and limited function of the body • Unlike CT, MRI uses no ionizing radiation. Rather, it uses a powerful magnetic field to align the nuclear magnetization of (usually) hydrogen atoms in water in the body

18. MRI

19. 0 • Electron arrangement determines the chemical properties of an atom • Electrons in an atom are arranged in shells, which may contain different numbers of electrons Outermost electron shell (can hold 8 electrons) First electron shell (can hold 2 electrons) Electron Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8 Hydrogen (H) Atomic number = 1 Carbon (C) Atomic number = 6

20. 0 Electron arrangement • Atoms whose shells are not full, tend to • interact with other atoms • Atoms gain, lose, or share • electrons • These interactions form • chemical bonds

21. Chemical Bonds

22. 0 • Types of Bonds • 1) Ionic bonds are attractions between ions of opposite charge • When atoms gain or lose electrons • Charged atoms called ions are created – + Transfer of electron – – Cl Na Cl Na Cl–Chloride ion Na+Sodium ion ClChlorine atom NaSodium atom Sodium chloride (NaCl)

23. Na+ Cl– 0 • Sodium and chloride ions • Bond to form sodium chloride, common table salt • An electrical attraction between ions with opposite charges • Results in an ionic bond

24. 2) Covalent bonds join atoms into molecules through electron sharing • In covalent bonds, two atoms share one or more pairs of outer shell electrons, forming molecules 0

25. Electronegativity • Electronegativity refers to the tendency of an atom to attract electrons in a covalent bond • Oxygen (3.5) has a high electronegativity • Hydrogen (2.1) and Carbon (2.5) have lower affinities • A bond between carbon and hydrogen will have nearly equal sharing of electrons (non polar) • A bond between oxygen and hydrogen will be highly polar • If the atoms have a large difference in electronegativity (>1.8) then the electron is shared so unevenly that it produces an ionic bond.

26. Electronegativity

27. 0 In a polar covalent bond electrons are shared unequally between atoms, creating a polar molecule O (–) (–) (+) (+) H H

28. 3) Hydrogen Bonds • Hydrogen bonds are weak bonds important in the chemistry of life • The charged regions on water molecules are attracted to the oppositely charged regions on nearby molecules • This attraction forms weak bonds called hydrogen bonds • Hydrogen bonding occurs in other biologically important compounds such as proteins and DNA. (–) Hydrogen bond (+) H O (–) (+) H (–) (+) (–) (+)

29. Molecular Shape

30. Shapes of Molecules

31. WATER’S LIFE-SUPPORTING PROPERTIES 0 • Water is the solvent of life • Polar or charged solutes dissolve when water molecules surround them, forming aqueous solutions Na+ – Na+ – + Cl– + – – + – + Cl– – + – + – + – – Ion insolution Saltcrystal

32. Hydrophobic and Hydrophilic molecules • Nonploar molecules do not form hydrogen bonds with water and are ‘excluded’ from associating with water • These molecules are said to be hydrophobic • Hydrophobic molecules such as oxygen require carrier proteins for transportation in the body • Polar molecules can form hydrogen bonds with water and are said to be hydrophilic

33. Cell Membrane

34. WATER’S LIFE-SUPPORTING PROPERTIES 0 • Hydrogen bonds make liquid water cohesive • Due to hydrogen bonding • Water molecules can move from a plant’s roots to its leaves by adhesion • Insects can walk on water due to surface tension • Created by cohesive water molecules

35. WATER’S LIFE-SUPPORTING PROPERTIES 0 • Water’s hydrogen bonds moderate temperature • Water’s ability to store heat • Moderates body temperature and climate • It takes a lot of energy to disrupt hydrogen bonds - So water is able to absorb a great deal of heat energy without a large increase in temperature • As water cools - A slight drop in temperature releases a large amount of heat

36. 0 • Ice is less dense than liquid water • Hydrogen bonds hold molecules in ice farther apart than in liquid water • Ice is therefore less dense than liquid water which causes it to float • Floating ice protects lakes and oceans from freezing solid Hydrogen bond Liquid water Hydrogen bondsconstantly break and re-form Ice Hydrogen bonds are stable Figure 2.13

37. The chemistry of life is sensitive to acidic and basic conditions • A compound that releases H+ ions in solution is an acid • And one that accepts H+ ions in solution is a base • Acidity is measured on the pH scale from 0 (most acidic) to 14 (most basic or alkaline)

38. 0 0 pH scale • The pH scale 1 H+ H+ H+ OH– H+ 2 Lemon juice, gastric juice • The pH of most cells Is kept close to 7 (neutral) by buffers • Buffers are substances that resist pH change OH– H+ H+ H+ H+ 3 Increasingly ACIDIC(Higher concentration of H+) Grapefruit juice, soft drink Acidic solution 4 Tomato juice 5 6 Human urine OH– OH– NEUTRAL[H+]=[OH–] OH– 7 Pure waterHuman blood H+ H+ OH– OH– H+ H+ H+ 8 Seawater Neutral solution 9 10 Increasingly BASIC(Lower concentration of H+) Milk of magnesia 11 Household ammonia OH– OH– 12 OH– OH– H+ Household bleach OH– OH– 13 OH– H+ Oven cleaner Figure 2.15 14 Basic solution

39. 0 • Acid precipitation threatens the environment • Some ecosystems are threatened by acid precipitation • Acid precipitation is formed when air pollutants from burning fossil fuels combine with water vapor in the air to form sulfuric and nitric acids • Can kill trees and damage buildings

40. Acid, Bases and Buffers • Ionization of Water • in pure water the concentration of the hydronium ion is 1.0x10-7mol/L • the pH is defined as the negative logarithm of the hydronium ion concentration • In pure water the pH=-log1.0x10-7 • = 7

41. Strong Acids and Bases • Strong acids and bases completely ionize in water

42. Weak Acids and Bases • Ionize partially in water

43. Weak Base • 10% ionization

44. Buffers • a chemical system containing a substance that can donate H+ ions when required or remove H+ when too many are in solution • therefore resist changes in pH