Matter is something that takes up space and has mass. There are two forms that matter can take which are the following: a substance and a mixture of substances. A substance (pure substance) is matter that is uniform in its composition. There are two types of substances which are defined below.
- Element:
- Is the simplest form of matter that has a unique set of properties.
- Cannot be broken down into simpler substances
- In 2.2, you saw a periodic table. Each box represents an element. An uppercase Letter or an uppercase Letter and a lower case letter is an element. For example,
- Boron (B)
- Sodium (Na)
- Compound
- Is a substance that contains two or more elements chemically combined in a fixed proportion.
- Can be broken down into simpler substances by chemical means.
- There are three components of a compound.
- Symbols: show the element(s)
- Subscript: show the number of atoms of each element
- Coefficients: show the number of molecules
When dealing with elements or compounds, you need to be able to count the number of atoms in the element or compound. An atom is the basic unit of an element or compound. For example, if you have Na, you have 1 atom. If you have 2Na, you have 2 atoms. If you have NaCl, you have 2 atoms as well because you have 1 Na and 1 Cl. If you have 3NaCl, you have 6 atoms because you have 3 NaCl's (NaCl, NaCl and NaCl), so you have 3 Na's and 3 Cl's.
Understanding the differences in terminology above will become very crucial to your understanding of Chemistry when you learn more about chemical equations. Check out the video below.
https://youtu.be/VERCurM8q_E
Matter can be a pure substance which is 1 element or 1 compound, such as oxygen, nitrogen, iron, distilled water, etc..., but matter can also be a mixture. A mixture is more than 1 pure substance. A mixture can be separated into pure substances by physical means, and can be a physical blend of two or more components. Examples of mixtures are chicken noodle soup and the air. There are two types of mixtures. You can see these two different types below.
Homogeneous Mixture: A Mixture in which the substances are EQUALLY spaced, it is the same throughout the entire mixture.
- Examples: Chocolate ice cream, or coffee
- Examples: Moose track ice cream, or orange juice with pulp
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https://youtu.be/Q0s71cjCNWs
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Filtration: Separates a mixture if the particles have different sizes. A filter has tiny openings in it. The small particles can go through those small openings while the large particles will stay behind. For example, when you separate cooked pasta from the cooking water. The water goes through the holes in the strainer, but the pasta does not. This is filtration.
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https://youtu.be/xxNfJLMNS4E
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Distillation: Separates mixtures based on their boiling points when there are large differences with the boiling points. The mixture is heated, and the components that have the lowest boiling point turn into a gas first, and will rise up then cool back down into a liquid and go into a different container.
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https://youtu.be/hp8H54gMK6Q
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Evaporation: Takes a mixture that has a liquid and solid component, such as sand mixed with water. This mixture is heated. The water turns into a gas (evaporation) and the sand is left behind.
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https://youtu.be/KEXWd3_fM94
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Centrifuging: Separates a mixture based on the property of density. A sample is placed in a test tube, and the test tube is placed in a centrifuge. The centrifuge will spin the sample really fast. When this occurs, the denser substances move towards the bottom of the test tube. An example of this would be separating blood cells from plasma.
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Note: Only watch from 0:00 to 2:40.
https://youtu.be/23W5Z_redfs
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Chromatography: Is a separation technique based on the rate that parts of a mixture move through other substances. There are different types of chromatography, but we will focus on paper chromatography. In paper chromatography, a mixture is placed on paper; the paper is called the stationary phase. One end of the paper is placed in a solvent. A solvent is a fancy word for saying a liquid that can dissolve something. An example of a solvent would be water or alcohol. In this case the solvent is the mobile phase. The mobile phase will move up the paper and the solvent will take the mixture with it up the paper. The different parts of the mixture will move up the paper at a different rate. Although we will be focusing on paper chromatography in this class, there are other form of chromatography (liquid chromatography, or gas chromatography) in which the stationary phase could be a liquid or gas, or the mobile phase moves down.
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https://youtu.be/K_QJMQUX6bo
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Osmosis: Osmosis is passing a solution across a selectively permeable barrier. NOT necessarily based on size of molecules. This barrier only allows certain substances to pass through (generally water is the substance that passes through). Water will move from areas of high water concentration to low water concentration. For example, the cell membrane allows water to pass through, but not some other substances. Check out the video (https://youtu.be/K_QJMQUX6bo ) below.
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