A Matter of Fact Mixtures, Elements and Compounds

What are the three most common phases of matter? Solid Solid Liquid Liquid Gas Gas Another phase of matter is Plasma Another phase of matter is Plasma

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.

Why isn’t matter classified according to its physical characteristics, such as color? Why isn’t matter classified according to its physical characteristics, such as color? Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together. Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.

Physical and Chemical Properties of Matter

Physical Property- characteristics of a material such as size, color, shape, and texture

What are some physical properties of the flowers below?

Physical Change Change in a physical property or change in phase Change in a physical property or change in phase For example: For example: Changing color Changing color Changing from solid to liquid, or liquid to gas Changing from solid to liquid, or liquid to gas Physical changes can be reversed or undone.

Chemical Properties Property, or behavior, of a substance when it undergoes a reaction or chemical change Property, or behavior, of a substance when it undergoes a reaction or chemical change Examples: Toxicity and Flammability Examples: Toxicity and Flammability

Chemical Change The chemical composition of a substance is altered The chemical composition of a substance is altered Breaking down of atomic bonds Breaking down of atomic bonds New substances formed New substances formed Examples: burning wood, iron rusting

Is this a physical or chemical change?

Is evaporation and condensing of water into clouds a physical or chemical change?

When observing properties of matter, scientists must ask themselves these questions: 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?

By asking these questions scientists can classify matter into: Elements – simplest form of pure substance. They cannot be broken into anything else by physical or chemical means. Elements – simplest form of pure substance. They cannot be broken into anything else by physical or chemical means. Compounds – pure substances that are the combination of two or more elements. They can be broken into simpler substances by chemical means. Compounds – pure substances that are the combination of two or more elements. They can be broken into simpler substances by chemical means. Mixtures – two or more substances that are not chemically combined and can be separated by physical means. The substances in a mixture retain their individual properties. Mixtures – two or more substances that are not chemically combined and can be separated by physical means. The substances in a mixture retain their individual properties. Solutions – a special kind of mixture where one substance dissolves in another. Solutions – a special kind of mixture where one substance dissolves in another.

Can it be separated by physical means? If the answer is no, the matter is a pure substance. If the answer is no, the matter is a pure substance. An element An element Or a compound Or a compound

Elements Elements are the simplest pure substance. Elements are the simplest pure substance. An element can not be changed into a simpler substance by heating or any chemical process. An element can not be changed into a simpler substance by heating or any chemical process. The smallest particle of an element that has the properties of that element is called an atom. The smallest particle of an element that has the properties of that element is called an atom. An atom is the basic building block of matter. An atom is the basic building block of matter. There are over 100 known elements in the universe listed on the periodic table of elements. There are over 100 known elements in the universe listed on the periodic table of elements. These elements combine in such a way to create millions of compounds. These elements combine in such a way to create millions of compounds.

Elements All elements are made of atoms. All elements are made of atoms. Atoms of the same element are alike. Atoms of the same element are alike. Atoms of different elements are different. Atoms of different elements are different.

Common Elements AluminumAl OxygenO CalciumCa CarbonC GoldAu HeliumHe HydrogenH NitrogenN

Top Ten Elements in the Universe Percent Element (by atoms) 1.Hydrogen Helium Oxygen Carbon Neon Iron Nitrogen Silicon Magnesium Sulfur Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 26

Compounds Compounds are also pure substances. Compounds are also pure substances. But compounds are made from more than one element. But compounds are made from more than one element. Water is a compound. Water is a compound. Water can be broken down into simpler substances – hydrogen and oxygen. Water can be broken down into simpler substances – hydrogen and oxygen.

Is it uniform throughout? If the answer is no, the matter is a heterogeneous mixture. If the answer is no, the matter is a heterogeneous mixture. Considered the “least mixed.” Considered the “least mixed.” 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. Particles are large enough to be seen and to be separated from the mixture.

Examples of heterogeneous mixtures Sand and pebbles Sand and pebbles Oil and water Oil and water Powdered iron and powdered sulfur Powdered iron and powdered sulfur

Granite is a heterogeneous mixture.

Is it uniform throughout? If the answer is yes, the matter is homogeneous (looks the same throughout). If the answer is yes, the matter is homogeneous (looks the same throughout). That leads us to another question. That leads us to another question.

Can it be separated by physical means? If the answer is yes, the matter is a homogeneous mixture or solution. If the answer is yes, the matter is a homogeneous mixture or solution.

Homogeneous Mixtures A mixture that appears to be the same throughout. A mixture that appears to be the same throughout. It is “well mixed.” It is “well mixed.” The particles that make up the mixture are very small and not easily recognizable. The particles that make up the mixture are very small and not easily recognizable.

Examples of homogeneous mixtures Milk, toothpaste, and mayonnaise are homogeneous mixtures. They are also colloids.

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 suspended. The particles are relatively large and suspended.

Tyndall Effect The lager particles cause light to scatter The lager particles cause light to scatter Colloids often seem cloudy. Colloids often seem cloudy.

Solutions Solutions Solutions Mixtures that have the same composition, color and density throughout Mixtures that have the same composition, color and density throughout Also called homogenous mixtures Also called homogenous mixtures Made of a solute and a solvent Made of a solute and a solvent Can be solids, liquids or gases Can be solids, liquids or gases

Solutes and Solvents Solute Solute Substance being dissolved Substance being dissolved Solvent Solvent Substance doing the dissolving Substance doing the dissolving

What do you think is the universal solvent? (what is usually used to dissolve things?)

The universal solvent: Water

Water as a solvent Many liquid solutions contain water as the solvent. Many liquid solutions contain water as the solvent. For example: Ocean water is a water solution that contains many salts. For example: Ocean water is a water solution that contains many salts. Body fluids are also water solutions. Body fluids are also water solutions.

What is the term for a substance dissolved in water? Aqueous Solution

Rate of Dissolving Rate of Dissolving Rate of Dissolving Stirring Stirring Speeds up dissolving Speeds up dissolving Brings fresh solvent to solute particles Brings fresh solvent to solute particles Crystal Size Crystal Size Smaller particles, faster dissolving Smaller particles, faster dissolving Increases surface area Increases surface area Temperature Temperature Speeds up the movement of the particles Speeds up the movement of the particles

Polarity of water Polar Polar Most substances dissolve in water Most substances dissolve in water Water is polar Water is polar A molecule of water has positive end and negative end A molecule of water has positive end and negative end Opposite charges attract and dissolving begins Opposite charges attract and dissolving begins

Ions Charged Particles Charged Particles Electrolyte- Electrolyte- a liquid or gel that contains ions Non-Electrolyte- substance that does not conduct electricity when dissolved in water

Types of solutions GasGas Air (oxygen in nitrogen) GasLiquid Soda water (carbon dioxide in water) SolidLiquid Ocean water (salt in water) SoluteSolventExampleSolidSolid Gold jewelry (copper in gold) Solid solutions- Metals dissolved in metals are called: ALLOYS

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

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

Suspension- A mixture where particles settle after standing for a while Examples: Italian dressing, sand in water, and ketchup.