YBTC - S3 - Types of Matter

Types of mixtures

A mixture can be classified as either homogeneous, heterogeneous or colloid

EXAMPLE OF HETEROGENEOUS MIXTURE:

A peanut butter and jelly sandwich is a heterogeneous mixture. You can see the different layers of bread, peanut butter, and jelly. Another example of a heterogeneous mixture is beach sand. Surprised? If you look closely, you'll be able to tell. You can see different colors from the different substances (shells, pebbles, etc.) in the beach sand. No two handfuls of the sand are exactly the same.

EXAMPLE OF A SOLUTION:

Dissolving salt into water creates a saltwater solution. In salt water, the solvent is water. The solute is salt. Some solutions may have more than one solute dissolved in the solvent. Soda pops are homogeneous mixtures made up of many different solutes. These solutes include sugar and carbon dioxide gas. These solutes are all dissolved in water (the solvent).

Mixture:

two or more substances that are combined physically. Most of the things around you are mixtures.

Types of compounds

• A binary compound is made up of two elements, such as sodium chloride (NaCl) and carbon dioxide (CO2). • A ternary compound is made up of three elements, such as glucose (C6H12O6) or silver carbonate (Ag2CO3).

Examples of homogeneous mixtures

• Brass and bronze are examples of homogeneous mixtures made of metals. They are metal alloys (see the Industrial Applications of Chemistry section from Chemistry Concepts in Action). • In liquid or gas form, homogeneous mixtures are usually called solutions (see the subsection on Chemicals by Volume—Solutions from Chemistry Connections).

What is matter?

Matter is anything that has mass and takes up space. Matter is all around you!

Examples of pure substances

Pure water and carbon dioxide gas are examples of pure substances.

Emulsions often have a cloudy appearance.

The boundary between the different parts of the emulsion scatters the light that passes through it. If you pour vinegar and then oil in a glass, the oil will rest on top of the vinegar. If you look at the boundary between the oil and vinegar, it will look cloudy.

Different parts that make up a mixture have different properties. EXAMPLES:

Tossed salad is a mixture because it is made of different parts—lettuce, carrots, and dressing. Salt water is a mixture, too. It is made of salt and water. However, salt water is a homogeneous mixture, so it looks the same throughout.

EXAMPLE OF ALLOTROPES:

Two solid allotropes of carbon are graphite (pencil lead) and diamond. They are both solid forms of carbon. However, graphite is a dark gray, waxy substance. Diamond is a hard, clear substance. Why are two solid forms of the same element so different? The answer is that the carbon atoms are arranged in a different pattern.

Solution:

a homogeneous mixture in which one or more substances (solutes) are dissolved in another substance (solvent). Solutions are made up of elements or compounds mixed together at a very fine level (molecular level).

Colloid:

a mixture in which very small particles are spread evenly through another substance. The particles in a colloid usually have a size of about one micrometer to one nanometer. Because of the tiny size of those particles, some colloids look like solutions. However, the particles in a solution are even smaller than the particles in a colloid. (Particles in a solution are more like the size of molecules. Think nano and smaller!) You just can't see this difference without a powerful microscope.

Compound:

a pure substance made up of two or more elements joined in a defined ratio. • In nature, most elements are found in combination with other elements. They are found as compounds. • There are millions of different known compounds. Scientists develop and study new compounds every day.

Element:

a pure substance that cannot be broken down by normal chemical or physical means. Elements are considered the simplest substances. An element is made of only one type of atom. It is identified by its atomic number. An element's atomic number sets it apart from other elements.

Heterogeneous mixture:

a type of mixture in which the makeup is not the same throughout. Heterogeneous mixtures are not mixed evenly. They may not appear uniform. (They do not appear to be the same all the way through.)

Homogeneous mixture:

a type of mixture that is considered to be the same throughout. Homogeneous mixtures are mixed evenly. Therefore, each part of the mixture seems to be the same.

Aerosols:

colloidal suspensions of liquid or fine solid particles in a gas. - Fog, mists, clouds, and sprays are aerosols with liquid particles. - Smoke is an aerosol with solid particles.

Sols:

colloids made of fine solid particles in a liquid or another solid. - Paints, muddy river water, and sewage are liquid sols. - Pearls, colored glass, and pigmented plastics are solid sols.

Foams:

consist of gases finely spread throughout liquids or solids. - Whipped cream and soda pop foam are liquid foams. - Marshmallows and StyrofoamTM are solid foams.

Gels:

consist of liquids spread throughout a solid, such as jelly, butter, and cheese

Emulsions:

consist of liquids spread throughout other liquids. Examples include oil and vinegar salad dressing, hand cream, and mayonnaise.

Allotropes:

different forms of the same element in the same physical state of matter.

All matter is made up of

elements or combinations of elements.

Greek prefix "hetero" means

"different"

The suffix "genos" means

"kind."

Greek prefix "homo" means

"same"

Some substances will dissolve more easily than other substances.

- A substance that dissolves in another substance is soluble. Salt and ethanol are soluble in water. - If a substance does not dissolve, it is insoluble. Butter and other lipids are insoluble in water (see the subsection on Chemistry in the Human Body from Chemistry Concepts in Action). - Just because a substance is soluble in one thing does not mean it is soluble in everything. While salt is soluble in water, it is insoluble in oil.

Rules for Allotropes

- Allotropes contain only one type of atom. However, the way that the atoms are arranged is different. Therefore, the different arrangements of atoms give the allotropes different properties. - Each allotrope is a pure form of that element.

Do all elements have allotropes?

- Only certain elements have allotropes. Some of those elements are carbon, oxygen, tin, phosphorus, and sulfur. Oxygen has two gaseous allotropes. They are O2 (diatomic oxygen) and O3 (ozone). Two solid allotropes of tin are gray tin and white tin.

Matter can be divided into two main categories:

1. Pure substance 2. Mixture

EXAMPLE OF HOMOGENOUS MIXTURE:

Apple juice is a homogeneous mixture. The juice at the top of your glass is the same as the middle and the bottom. The juice looks the same in every part of the glass. Any sip of the juice should taste the same.

Emulsions are often unstable.

Homemade oil and vinegar salad dressing is an unstable emulsion. It will quickly separate unless you shake it continuously. Shaking the emulsion keeps the parts mixed. However, the oil and vinegar do not want to be mixed together. Droplets of oil will try to find and combine with other oil droplets. The oil droplets will continue to combine with each other until they are completely separated from the vinegar. When small droplets recombine to form bigger ones, the process is called coalescence

Colloids consist of fine particles of one substance mixed into another. The fine particles in a colloid are suspended and dispersed throughout the substance.

There are: Sols, Gels, Foams, Aerosols, Emulsions

Solute:

the substance that is dissolved in the solution. The solute is mixed into the solution completely so that it seems to almost disappear. The solute is usually the substance that is present in a lesser quantity. (There is usually a smaller amount of it in the solution.)

If a substance does not dissolve, it is ...

insoluble.

A substance that dissolves in another substance is ...

soluble.

Pure substance:

something that has a specific composition (makeup) that does not change.

Solvent:

the substance that does the dissolving. The solvent is usually the substance that is present in a greater quantity. (There is usually a greater amount of it in the solution.)

Rules for pure substances:

• Pure substances can be either elements or compounds. • Pure substances have the same composition throughout.

Is water a compound

• Pure water is a compound of hydrogen and oxygen atoms bound together in a 2:1 ratio. The ratio means that 2 hydrogen atoms are joined to 1 oxygen atom. Therefore, the chemical formula for water is H2O. Other familiar compounds include table salt (NaCl), glucose (C6H12O6), and sulfuric acid (H2SO4).

Rules for Mixtures

• The chemical structure (composition) of each part of a mixture stays the same. Therefore, scientists can separate mixtures into their original parts (see the subsection on Physical and Chemical Separations). • The different parts of a mixture are arranged randomly.