2. Mass is a measure (a numerical quantity) of how much matter is present. Atoms are made up of protons and neutrons and each one has a mass of 1 mass unit. (Like grams but much, much smaller) Mercury (Hg) atoms consist of 80 protons and 120 neutrons and weigh 200 mass units each. For Example: Lead (Pb) atoms consist of 82 protons and 125 neutrons and weigh 207 mass units each. What is mass?  Lead atoms weigh more than mercury atoms because they contain more matter. Obj. 2.04

3. 0.0 0.0 Both boxes have a volume of 1 cm 3 Fill the boxes up with their corresponding atoms. - - - - - 11.3 13.5 The mercury box has a larger mass (even though mercury atoms don’t weigh as much as lead) because the mercury atoms are packed in more tightly.  Density is a measure of how much matter is stuffed into a particular volume…most often 1 mL or 1 cm 3. Obj. 2.04

4. Properties of Matter Matter: anything that has mass and takes up space Substance: matter that has a uniform and unchanging composition. (i.e. you can write a formula for it) An element is a substance that has only one kind of atom. Gold (Au) A compound is a substance that has two or more types of atoms in fixed proportions. Water (H 2 O) Obj. 2.04 There are only two types of substances:

5. Law of Definite Proportions A chemical compound always has the same ratio of elements (ex 2H and 1 oxygen in H 2 O). How many grams of hydrogen and oxygen would be in 10 g of water? In 59 grams of water? 1.1 g of hydrogen, 8.9 g of oxygen 6.5 g of hydrogen, 52.5 g of oxygen (11% hydrogen, 89% oxygen) Given: One gram of water contains 0.11 g of hydrogen and 0.89 g of oxygen. Obj. 3.02

6. Substances are identified by their... Physical and Chemical properties

7. Substances are identified by their... Physical and Chemical properties

8. Physical properties can be observed and measured WITHOUT permanently changing the material. Examples: Color, shape, hardness, odor, texture, state of matter (solid, liquid or gas), reflectivity, temperature, viscosity Chemical properties can only be observed or measured by PERMANENTLY CHANGING the material. Examples: Flammability, toxicity, acidity, radioactivity, reactivity with oxygen, light sensitivity Obj. 2.04 Obj. 5.03

9. Physical property: Odor depends upon molecular shape Thus, a change in odor indicates that the substance has been changed into a new substance Obj. 2.04

10. Examples of intensive physical properties: Density-mass contained in 1 mL of material Melting point-Temperature at which material begins to melt Freezing point-Temperature at which material begins to freeze Boiling point-Temperature at which material begins to boil Intensive properties do not depend upon the amount of matter that is present. Extensive properties depend upon the amount of matter that is present. Examples: total mass, volume, length Obj. 2.04

11. Physical changes change the appearance of the substance WITHOUT changing the substance’s formula. Examples: Melting, dissolving, freezing, boiling, grinding, breaking Chemical changes result in the formation of a new substance (the formula changes). FIVE INDICATORS OF CHEMICAL CHANGE  Gas evolution (bubbles)  Color or odor change  Energy given off (flames)  Temperature change  Precipitate (a solid) formation It is VERY important to know these!!!

12. Chemical or physical change? 1. When heated, a substance goes from a liquid to a gas. 2. When heated, the color of a substance changes from blue to white. 3. When heated, a substance burns. 4. When hit with a hammer, a substance explodes. PHYSICAL! CHEMICAL!

13. Chemical or physical change? 5. When hit with a hammer, a substance flattens. 6. When hit with a hammer, a substance breaks apart into smaller pieces. 7.When water is added to a blue liquid, it changes to a lighter blue. 8. When a clear liquid is added to a blue liquid, a white solid is formed. PHYSICAL! PHYSICAL or CHEMICAL! CHEMICAL!

14. Chemical or physical change? 9.When water is heated, small bubbles form on the bottom of the container. 10.When water is added to concrete mix, the water begins to steam. 11. When water is added to dry sand, bubbles are observed coming up from the sand. 12. When water is added to a metallic solid, the metal melts and smoke is given off. CHEMICAL! PHYSICAL! CHEMICAL!

15. Conservation of Mass Practice Problems 23 g of sodium metal is reacted with 35 g of chlorine gas to form sodium chloride as its only product. What was the weight of the sodium chloride that was formed? ReactantsProducts Sodium + Chlorine Sodium chloride 23 g35 g=58 g+ Obj. 5.02 Law of conservation of mass: matter is neither created nor destroyed during a physical or chemical change or….”What goes in must come out.”

16. Conservation of Mass Practice Problems 100 g of lard is reacted with 50 g of lye to form glycerin and soap. How much soap was formed if 25 g of glycerin was produced? ReactantsProducts Lard + lyeGlycerin + soap 100 g+50 g=25 g+125 g Obj. 5.02

17. Examples of intensive physical properties: Density-mass contained in 1 mL of material Melting point-Temperature at which material begins to melt Freezing point-Temperature at which material begins to freeze Boiling point-Temperature at which material begins to boil Intensive properties do not depend upon the amount of matter that is present. Extensive properties depend upon the amount of matter that is present. Examples: total mass, volume, length Obj. 2.04

18. Mixture: a combination of two or more substances. The composition of mixtures is variable. Uh oh!

19. Heterogeneous mixture: a mixture in which the physical properties are different in different parts of the mixture. heterogeneous Homogeneous mixture: a mixture in which the physical properties are the same throughout. A solution soluble dye

20. Types of solutions Gas/gas Gas/liquid Liquid/liquid Solid/liquid Solid/solid Air is 78% N 2 and 21% O 2 Carbonated sodas are made by dissolving CO 2 gas in water 8 carat gold is a solid solution of Cu, Ag and Au Vinegar is 5% acetic acid, 95% water Sports drinks are 0.1% NaCl, 5% sugar and 94.9% water.

21. Viscosity: a fluid’s resistance to flow. Viscous (which sounds like mucus) fluids have a high viscosity. Viscosity as temperature Obj. 2.04

22. Separating Mixtures Mixtures can be separated by taking advantage of differences in physical properties. Filtration: a porous barrier is used to separate a solid from a liquid. The filter can only separate out particles of solid that are LARGER than the pores through the filter.

23. Distillation: separation of substances by differences in boiling point. The substance with the lower boiling point will distill off first.

24. Crystallization: formation of a pure solid substance from a solution containing the dissolved substance. Sodium acetate in water p-dichlorobenzene in chloroform

25. Chromatography: separates two dissolved substances by their solubility in the solvent. The more soluble substance travels faster up the stationary phase.

26. Law of conservation of mass: matter is neither created nor destroyed during a physical or chemical change or….What goes in must come out. Ex 1: 23 g of sodium metal is reacted with 35 g of chlorine gas to form sodium chloride. How much sodium chloride was formed? 23 g sodium + 35 g chlorine 58 g of sodium chloride reactantsproducts Ex 2: 56 g of iron reacts with oxygen to form 80 g of iron oxide. How many grams of oxygen were used in the reaction? 56 g iron + x g of oxygen 80 g of iron oxide x = 24 g of oxygen

27. mass of the part mass of the whole x 100 Mass% = Ex 1: A sample of water contains 2 g of hydrogen and 16 g of oxygen. What is the mass% of hydrogen and oxygen in water? Ex 2: A compound containing only carbon and oxygen is 27% carbon. How many grams of oxygen are present in a 100 g sample of the compound?  If 27% of the compound is carbon, then 73% of the compound is oxygen.  73% of the 100 g sample weight  73 g of oxygen

28. An anhydrous crystal contains no water Hydrates: a crystalline material that contains a fixed percentage of water molecules within its crystal structure. Solids can have a variable amount of water adsorbed onto their surfaces. A crystal hydrate has a constant amount of water molecules within its crystal lattice.

29. Ex 1: 243 g of barium chloride dihydrate (BaCl 2 2 H 2 O) are heated until the compound is anhydrous. What is the final weight of the compound if the hydrate is 15% water? 15% of compound is water 85% of compound is anhydrous crystal  0.85 (243 g) = 207 g Ex 2: 141 g of a hydrate are heated strongly until a constant weight of 60 g is obtained. What was the %water in the hydrate? Mass of water = 141 g hydrate – 60 g anhydrous = 81 g of water