WHMIS is a nationwide system designed to protect Canadians and provide workers and employers with vital information about hazardous materials used in the workplace. WHMIS helps you tell if a material is hazardous, type of risk, how to handle a material safely. Information is provided by means of labels, material safety data sheets (MSDS) and training. WHMIS labels: 1 Warning symbols that are on household containers Ex. Cleaners such as bleach FAMILY/GROUP: elements in vertical columns – have similar properties. Reactivity INCREASES from top to bottom within groups 1 and 2 Reactivity DECREASES from top to bottom in groups 17 & 18. (Fluorine is the most reactive non-metal) PERIOD: elements in horizontal rows – these elements change from metals to nonmetals. Alkali Metals: Group 1 metals Soft, silver coloured metals that react violently with H O 2 to form basic solutions Most reactive: cesium & francium 2 Alkaline Earths: Group 2A metals Light, reactive metals that form oxide coatings when exposed to air Halogens: Group 17, non-metals, highly reactive. Fluorine is the most reactive Noble Gases: Group 18 Generally unreactive (inert) Reading the periodic table: 3 Significant digits: 1. All digits 1-9 are significant Ex. 123 ( 3 sig digs) With zeros it gets more complicated… 3. leading zero’s are not significant Ex. 0.12 (2 sig digs) 4. Zero’s to the right are only significant if: A. units are attached to the number Ex. 100 g (3 sig digs) 4 B. In scientific notation 1.0 x 10 (2 sig digs) c. placed after other digits but behind a decimal point are significant; 7.90 (3 sig digs) Complete: WHMIS Worsksheet 1.1 Structure of Matter The Atom; smallest part of an element Is made up with 3 major particles: Protons (positive charge particle) Electrons (negative charge particle) Neutrons (neutral particle) 4 Atomic number – the number of protons in an element Calculating electrons: Atomic number in element Calculating neutrons: Atomic mass = n + p Neutrons = atomic mass – protons Always remember to subtract! Example: # of protons Element? # electrons # of neutrons Mg Fe Br Pb More examples: Element # of protons (Atomic #) # of electrons # of neutrons Lithium (Li) Titanium (Ti) Carbon (C) Chlorine (Cl) 5 Bohr Model: Niels Bohr developed a diagram to represent electrons and the energy levels of an atom. Each energy level can hold a certain maximum number of electrons equal to the number of elements in the period Bohr Diagram Steps: Step 1: see what row the element is in, and count how many elements in the row it is. (include element) All rows before the last one, are fully occupied with the max amount of electrons Include protons and neutrons at the bottom Examples: Oxygen Atom Sodium Atom 6 Lewis Dot Diagram – deals only with valence electrons Valence electrons – electrons in the last energy level Step 1: write symbol Step 2: determine valence electrons Step 3: place electrons in North, East, South and West positions. Place one at a time, with two maximum at each position. Carbon Example: Examples: Lithium Calcium Neon helium fluorine ** Atoms have one mission: to gain, loose, or share electrons, in order to become fully satisfied. 7 Diatomic: H , O Share pair of electrons 2 2 Polyatomic: share many pairs of electrons ex. Ammonium Atoms: Most stable when its outer energy level is full of electrons. A maximum of 8 electrons may occupy a valence energy level. This is known as the octet rule. If an atom gains electrons, it become negative charged If it loses electrons, it become positively charged Anion: element ion that gained electrons (negatively charged) Cation: electron ion that lost electrons (positively charged) Properties of: Metals: conduct, “magnetic”, malleable, ductile, loose e-, cations, silver, solid (except Hg) Non-metals: brittle, dull, does not conduct, gains e-, anions Can a metal and non metal bond? Yes, metal donates e- to the non metal (Ionic Bond) What about calcium oxide? All compounds have a net charge of 0, thus neutral (stable) 8 Complete: Page 8: 1, 2, 3; Page 9: 5; Page 13: 7; Page 14: 1, 2, 3, 6; Page 21: 11; Page 23: 1, 2, 4 1.3 Breaking Bonds Chemical change – occurs when a new substance is formed, accompanied by a change in color, odor, state, or energy Exothermic: chemical change when energy, usually in the form of heat, is released into the surroundings. Endothermic: a chemical change in which energy is absorbed from the surroundings. (substance usually gets colder) Solutions Solute: a substance that dissolves (salt) Solvent: a substance that does the dissolving and is in greater proportion in the mixture. (H 0) 2 Solutions are a good medium for chemical change, water is a good solvent 9 Why Water is a Good Solvent? All 3 physical states occur on earth under “normal” conditions Boiling point and melting point is higher than similar substances Polar molecule – molecule with a partial positive and negative charge Electrostatics – attracted to objects that are positive and/or negative (water will bend toward a charged object) Universal solvent o dissolve ionic compounds o + and – charges are produced with in sol’n Dissociation- separation of an ionic compound into individual ions in a solution o smaller parts (compound ions) Ionic compound: has a cation (metal) and an anion (non metal) Molecular compound: 2 non metals Electrolytes: electrolytes (conducts electricity when dissolved water) non-electrolytes (does not conduct electricity when dissolved in water) 10 Non- electrolytes: “Like dissolves like” ◦ Water can not break down covalent bonds in molecular compounds Concentration: amount of solute to solution (ratio) Concentration Vs Dilution qualitative analysis (observable property) ◦ color ◦ taste ◦ scent ◦ test the solution Conductivity pH (A greater concentration results in a higher/more intense property) 11 quantitative analysis (see pg. 10 in dada book) C V =C V i i f f C= molar concentration V= volume (L) C= n/V i= initial solution F=final solution n= # of moles (mol) Diluting Solutions: Example: CV = C V i i f f You have 65.0mL of a 0.759 mol/L solution of sodium chloride, NaCl (aq). Calculate the final concentration of the solution if it is diluted to a final volume of 100.0 mL. 12 Example: CV = C V i i f f You have 100.0mL of a 1.490mol/L solution of sodium chloride, NaCl (aq). Calculate the final volume of the solution if it is diluted to a final concentration of 0.500 mol/L Assignment: Page 27: 16, 17, 19; Page 30: 21, 23; Page 31: 24a-c; Page 33: 1-4; Page 39: 1, 2, 4, 5 13 1.5 CALCULATING CONCENTRATION / DILUTIONS % V/V = percent by volume concentration (V solute / V solution) x 100 Most commonly used for liquids dissolved in liquids PPM = parts per million 6 (m solute/ m solution) x 10 ppm Used for very dilute solutions ALWAYS … SOLUTE / SOLVENT! Helpful hints: Read the question carefully Is the solute included in the solvent? Remember the significant digits rule Remember the conversion factor for mL to L 1L = 1000mL Know how to read powers of ten in your calculator See page 43 Steps for completing problems: Step 1: write down what you know and don’t know Step 2: write down and rearrange your formula Step 3: plug in your numbers and include units 14 Percent by volume example: A hair product requires you to combine 20.0 mL of hydrogen peroxide with enough water to produce a solution with a total volume of 120.0 mL. Determine the percent by volume concentration of the solution. PPM example: -3 A 200 g sample from a bottle of water contains 5.4x10 g of mercury. Calculate the concentration of mercury in the sample in parts per million. 15 Concentration example: A sample of water taken from a nearby lake is found to have 0.0035 mol of salt in a 100 mL solution. Determine the concentration of the salt in the lake. ACIDS: a substance that produces hydrogen ions when dissolved in water to form a conducting aqueous solution. Turns blue litmus paper red. Conduct electricity (they are electrolytes) Taste sour Their pH ranges from 0 to 7 *Always add an acid to water, never add water to the acid. Bases: Bases are empirically defined as a substance that: Taste bitter Conduct electricity (they are electrolytes) Feel soapy or slippery Turns red litmus blue Their pH ranges from 7 to 14 Assignment: Page 42: 28-30; Page 44: 31-33; Page 46: 34-36; Page 50: 3738; Page 52: 1, 3, 4, 6a,b, 7a 16 Dilutions: Standard solutions Are: Are precise For comparisons Volume Color Preparing a solution: Example prepare 500 ml of a 1.2 mol/L copper II sulfate solution. And then dilute it to prepare 100 ml of a 0.12 mol/L calculate the required mass necessary to prepare the solution using n =cv and m= nM Solution 1: v1= 500mL 0.500L C1= 1.2 mol/L Solution 2: v2= 100mL 0.100L C2= 0.12mol/L n=cxv 0.500L x 1.2mol/L = 0.60mol M = nxM 0.6 mol x 159.62 g/mol = 95.8g (CuSO4) = 63.55+ 32.07+ (4x16) = 159.62g/mol 17 weigh the mass out on a electric scale pour the mass in to a 500 ml beaker dissolve the mass with approximately ¼ the required volume of solution transfer the solution to a 500 ml volumetric flask using a funnel add enough water to fill the volumetric flask I then need to calculate what volume of copper II sulfate solution is required to make my diluted solution n=cv of new solution v=n/c of old solution New diluted solution: n= c xv 0.12mol/L x 0.100l = 0.012mol 2 2 V= n/c 0.012mol/1.2mol/L = 0.01L = 10mL 1 pipet out that volume from my original solution and transfer it to a second 100 ml volumetric flask raise volume to 100 ml 18 Diluting solutions: CiVi = CfVf You have 85.0mL of a 0.655 mol/L solution of sodium chloride, NaCl(aq). Calculate the final concentration of the solution if it is diluted to a final volume of 150.0 mL. 19