Bellwork Q Tap water is not just H

Bellwork Q: Tap water is not just H 2 O. Guess 5 other things that are in the tap water (water that comes out of a faucet).

Section 1: Classifying Matter Vocabulary Objectives Pure substance Element n Understand the Atom classification of matter Compound n Distinguish between Heterogeneous mixtures & pure mixture substances Homogeneous mixture n Define & distinguish Solution between solutions, Suspension suspensions, & colloids Colloid

Classifying Matter There are many classification systems we use. n n n We classify books & music based upon their genre. We classify the safety of something based upon its ability to cause harm. We classify friends based upon how close they are to us.

Why Classify? When we classify items it helps us understand apply their unique properties. We know how to treat the matter, how to handle it, and what we might be able to do with it. Take for instance clothing. By classifying the material inside we know whether we can iron it or wash it with bleach.

Classifying Matter In order to begin to comprehend matter – its composition, structure, and the reactions that happen in matter – we need to know how to basically classify matter. What is matter? It’s any substance that has mass and is composed of atoms. An atom is the smallest unit of an element that retains the element’s properties. We’re beginning today by learning to classify matter based upon its composition = what matter is made of.

What is it?

Flow Chart: When we finish discussion, you’ll have an opportunity to fill this out.

Classifying Matter When classifying matter the first question you must answer is: “Does it have uniformity of composition? ” n Meaning: does it appear it’s all the same stuff? Sometimes you know, sometimes you are not sure. Based upon observations, analysis, or what you know about it, you can answer.

The First Question A uniform distribution means that you can’t see any obvious differences in the substance. Does it look like it’s all the same thing? If it does then it’s a homogeneous substance or mixture. If it doesn’t then it’s a heterogeneous mixture.

Homogeneous Substances & Mixtures: Substances with matter so evenly distributed that it is difficult to distinguish between the substances that comprise it. n n Fluid examples: Pool water (has dissolved substances mixed with water), the ocean, soda – What is dissolved in the carbonated water? pudding, cake batter Solid examples: Can also be something like cake mixes or… Metal alloys; Brass is a mixture of copper and zinc. The likelihood of picking the same molecule is still small but it would be hard to choose different ones.

Pure substances A fixed composition means that 100% is made of the same molecules. Pure substance: Matter that always has exactly the same elements in a fixed composition. n Ex: Salt, Sugar w Each individual molecule is comprised of the same molecular composition in its smallest form. n Pure Substances are classified into two categories w Elements n Copper (Cu), Gold (Au) w Compounds n n Salt (Na. Cl), Sugar (C 6 H 1206) The question to decide which is: “Can it be broken down into smaller, different parts? ”

Pure Substances “Can it be broken down into simpler parts? ” If ‘no’ then = it’s an element Elements: types of atoms on the periodic table Gold n Au Copper n Cu If ‘yes’ then = Compounds: bonded elements Salt: Sodium chloride n Na. Cl Sugar: Glucose, Fructose n C 6 H 1206

Elements: Pure Substances Elements n The millions of substances and organisms known/found are made up of a few of only about 100 elements in millions of combinations. w See periodic table of elements pg 133 or back cover n n Element = substance that only contains one type of atom. EXAMPLES: Any block on the periodic table. Atom = the smallest particle of an element w Gold is an element, it mass is comprised of gold atoms n n Most metallic elements are solids at room temperature Common Examples: w Metals: Magnesium, Carbon, Aluminum, Copper, Plutonium w Given abbreviation based upon Latin origins (Berzelius) n Some, like mercury, are not.

Compounds: Pure Substances Compounds: a substance formed from two or more atoms in a fixed ratio (given by the chemical formula w Can be broken down into either elements or compounds. w Are always formed of two or more elements joined in fixed proportion. w The proportion is defined by the chemical formula. n Ex: H 2 O = Water w Always 2 Hydrogen + 1 Oxygen n Another: C 6 H 12 O 6 = Glucose w Always: 6 Carbon, 12 Hydrogen, 6 Oxygen

Mixtures: If it’s not all the same… Mixtures: Composition of substances that is not uniform. n n n This means that the parts aren’t in the same proportion. Meaning that there a number of different things in different amounts making up the substance and the amounts of each is not ever exactly the same. Mixtures can be homogeneous or heterogeneous.

Homogeneous Solutions: Not all homogeneous substances are made of the same matter. Sometimes there are things mixed together but it’s hard to tell. Solutions: are Homogeneous substances formed when solutes are dissolved in a solvent. n Basically a solvent is a fluid that something else dissolves in. w Water is the “universal solvent”. w This means that almost anything will dissolve in it. w There are other solvents, like oil, or vinegar. n n The “something else” is called a solute: a substance that can be dissolved in a solvent. Ex: Salt or sugar dissolved in water; it’s a mixture of substances but its difficult to distinguish between its parts. Solutes dissolved in solvents form solutions.

Mixtures Heterogeneous mixtures: mixture where the parts are noticeably different. w Ex: Beach sand w Notice how each of the parts is different. w It’s made up of shell, quartz, coral, rock, wood, and other stones and debris. w To decide if it’s a heterogeneous mixture think about the likelihood of picking the exact same item twice in a row.

Heterogeneous Mixtures: Suspensions and Colloids Suspensions: Heterogeneous mixture of substances that will separate into layers over time w Ex: Salad dressing w Usually cloudy when mixed w The layers are and organic and aqueous. n One’s oil (organic) and the other’s water (aqueous)

Heterogeneous Mixtures: Suspensions and Colloids: Homogeneous mixture of small, medium, and large substances that will not settle over time. w Ex: Homogenized milk (heating causes the fat to stay dissolved) w Vs. Fresh milk (a suspension that will separate over time)

Suspension v. Colloid Suspensions and colloids differ from solutions due to the fact that they will scatter light. n n n This means that light waves will be redirected in various directions. It will cause the light to appear as a cone as it travels through the colloid. Have you ever seen a spot light shined through fog? Fog is a colloidal mixture. A colloid has a distinctive “milky” appearance.

Properties and Substances One thing to note, other than knowing how and when to use matter, Homogeneous Substances: have uniform properties throughout a substances while… Heterogeneous Substances: have different properties for the different substances added.

Flow Chart: Complete 1 2 Atom 3 4 6 Solution 5 Suspension 7 Colloid 8

Any Questions For Me? I Have A few For You. 1. Why does every sample of a given substance have the same properties? 2. 3. 4. 5. Every sample of a given substance has the same properties because a Answer substance has a fixed, uniform composition. Explain why the composition of an element is fixed. An element has a fixed composition because it contains only one type of Answer atom. Describe the composition of a compound. A compound always contains two. Answer or more elements joined in a fixed proportion. Why can the properties of a mixture vary? The properties of a mixture can vary because the composition of a Answer mixture is not fixed. On what basis can mixtures be classified as solutions, suspensions, or colloids? Based on the size of its largest particles, Answera mixture can be classified as a solution, a suspension, or a colloid.

Summary By understanding how to classify a material we can better understand its properties. Understanding its properties helps us to identify what it is. This all helps us understand matter. Now, write in your notes a reflection summary on how you could conduct a test that would determine if a sample was a pure substance or a mixture.

Summary n n Matter is classified into pure substances and mixtures Pure substances always have the same parts throughout Mixtures consist of more than one simple substance in no specific consistency. Mixtures can be categorized into homogeneous solutions, and heterogeneous suspensions, or colloids.

Test Your Understanding In-class Mini-lab. (25 pts) Objectives: n Using the knowledge you’ve gained from the lesson, identify what each of these sample materials are. Directions: n n n Identify if the substance based upon its uniformity of composition. Give a reason for your answer by describing the material. Neatly present this in a chart-style paper.

Directions: Observe the samples and use their compositions to decide on their category 1. Hypothesis: (5 pts) How can you use properties to classify substances? 2. Table: (5 pts) Construct this table on your own paper and fill in all boxes. Be descriptive as possible. Substance # Pure Substance/ Type: Mixture Be specific Reason/ Support/ Description 1. Salad Dressing 2. Buttons 3. Sand 4. C 6 H 12 O 6(sugar) 5. Tap Water 6. Milk 7. Na. Cl (Salt) 8. Pb (Lead) 9. Lime Soda 3. Conclusion: (15 pts) Write 1 paragraph explaining if your hypothesis was correct and how you can use properties to categorize matter.