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Elements, Compounds and Mixtures Elements, Compounds and Mixtures.

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Presentation on theme: "Elements, Compounds and Mixtures Elements, Compounds and Mixtures."— Presentation transcript:

1 Elements, Compounds and Mixtures Elements, Compounds and Mixtures

2 Elements, Compounds, Mixtures Elements, Compounds, Mixtures Ultimately, all matter can be classified as mixtures, elements and compounds Ultimately, all matter can be classified as mixtures, elements and compounds Questions to ask to help classify! Questions to ask to help classify! Is the matter uniform throughout? Is the matter uniform throughout? Can it be separated by physical means? Can it be separated by physical means? Can it be separated by chemical means? Can it be separated by chemical means?

3 Why isn’t it a good idea to classify matter by its phases? Because one kind of substance can exist in more than one phase – such as H 2 0. And matter changes phases rather easily. Because one kind of substance can exist in more than one phase – such as H 2 0. And matter changes phases rather easily.

4 Elements Elements are pure substance that cannot be separated into simpler substance by physical or chemical means. Elements are pure substance that cannot be separated into simpler substance by physical or chemical means.

5 Compounds Pure substance composed of two or more different elements joined by chemical bonds. Made of elements in a specific ratio Made of elements in a specific ratio that is always the same that is always the same Has a chemical formula Has a chemical formula Can only be separated by Can only be separated by chemical means, not physically chemical means, not physically

6 Compounds Water is a compound. Water is a compound. Water can be broken down into simpler substances – hydrogen and oxygen through electrolysis. Water can be broken down into simpler substances – hydrogen and oxygen through electrolysis.

7 Mixtures A combination of two or more pure substances that are not chemically combined. A combination of two or more pure substances that are not chemically combined. substances held together by physical forces, not chemical substances held together by physical forces, not chemical No chemical change takes place No chemical change takes place Each item retains its properties Each item retains its properties in the mixture They can be separated physically Chem4kids.com

8 Heterogeneous Mixtures Does not appear to be the same throughout. Does not appear to be the same throughout. Particles are large enough to be seen and to be separated from the mixture sometimes by filtering. Particles are large enough to be seen and to be separated from the mixture sometimes by filtering.

9 Examples of heterogeneous mixtures Sand and pebbles Sand and pebbles Chicken noodle soup Chicken noodle soup Granite Granite Oil and water Oil and water

10 Homogeneous Mixtures A mixture that appears to be the same throughout. A mixture that appears to be the same throughout. The particles that make up the mixture are very small and not easily seen The particles that make up the mixture are very small and not easily seen Cannot be separated by filtering Cannot be separated by filtering Some examples: salt water solution, kool aid, ice tea mix and water Some examples: salt water solution, kool aid, ice tea mix and water

11 Suspensions Are mixtures in which the particles are larger than ones found in solution. They are insoluble Are mixtures in which the particles are larger than ones found in solution. They are insoluble ( they don’t dissolve) and will settle out if left alone. They are heterogeneous. ( they don’t dissolve) and will settle out if left alone. They are heterogeneous. Examples: blood, oil and water, muddy water, snow globe, glitter and water Examples: blood, oil and water, muddy water, snow globe, glitter and water They also do not transmit light they scatter light or block light. They also do not transmit light they scatter light or block light. Can be separated by filtering Can be separated by filtering

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13 Colloids In a colloid the particles are mixed together but not dissolved. In a colloid the particles are mixed together but not dissolved. The particles are relatively large and are kept permanently suspended. The particles are relatively large and are kept permanently suspended. Cannot be easily filtered Cannot be easily filtered

14 Examples of Colloids milk, mayo, cheese, whipped cream, deodorant, fog, gelatin, milk, mayo, cheese, whipped cream, deodorant, fog, gelatin, smoke, toothpaste smoke, toothpastedetergents They are homogeneous mixtures

15 Solutions A solution is a type of homogeneous mixture formed when one substance dissolves in another. A solution is a type of homogeneous mixture formed when one substance dissolves in another. A solution always has a substance that is dissolved( the solute) and a substance that does the dissolving. ( the solvent) A solution always has a substance that is dissolved( the solute) and a substance that does the dissolving. ( the solvent)

16 The universal solvent: Water

17 Types of Solutions Types of Solutions Dilute-less solute than solvent. Dilute-less solute than solvent. Concentrated Concentrated Saturated- A solution which has as much solid dissolved in it, as it possibly can contain. Saturated- A solution which has as much solid dissolved in it, as it possibly can contain.

18 Concentration- the amount of a particular substance in a given quantity of a mixture Concentration- the amount of a particular substance in a given quantity of a mixture Solubility-the ability of one substance to dissolve in another at a given temperature and pressure Solubility-the ability of one substance to dissolve in another at a given temperature and pressure

19 Types of solutions GasGas Air (oxygen in nitrogen) GasLiquid Soda water (carbon dioxide in water) SolidLiquid Ocean water (salt in water) SoluteSolventExampleSolidSolid Brass ( copper and zinc).

20 Air is a solution of oxygen and other gases dissolved in nitrogen

21 Alloys are Mixtures Alloys are solid solutions of metals or nonmetals dissolved in metals. Alloys are solid solutions of metals or nonmetals dissolved in metals.

22 Alloys examples) Brass is an alloy of copper and zinc. Stainless steel is a mixture of iron and chromium.


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