Chapter 22.1 Classifying Matter

2.1 Classifying Matter• ___________-Matter that always has exactly the same

composition. There is a fixed, uniform composition.• Substances can be classified into two categories:

▫ Elements A substance that cannot be broken down into simpler

substances. There are just over _____elements.▫ _____- The smallest particle of an element.

An element has a______composition because it contains only one type of atom.

• No two elements contain the ___________of atom.

•Examples:

Pure Substances Con’t.• Compounds

▫ A substance that is made from two or more _______ substances and can be broken down into those simpler substances. The ___________ of a compound differ from those of the

substances from which it is made. A compound always contains two or more elements

joined in a _________________.

Mixtures• Mixtures tend to retain _______of the

properties of their individual substances. ▫ The properties of a mixture can

vary because the composition of a mixture is ____fixed.

▫ ________________Mixtures - The parts of the mixture are noticeably different from one another. Examples: salads, salsa

Mixtures▫Homogeneous Mixtures - The substances

are so _________________that it is difficult to distinguish one substance in the mixture from another. Examples:

Solutions, Suspensions, and Colloids

Solutions, Suspensions, and Colloids•Based on the size of its largest particles, a

mixture can be classified as a _________, ____________, or ______________.▫ Solution- Substances dissolve and form a

______________ mixture. Examples:

▫ Suspensions- Heterogeneous mixture that separates into ______ over time. Examples:

Solutions, Suspensions, & Colloids• Colloids- Contains some particles that are

_________ in size between the small particles of solutions and the large particles of suspensions. Colloids will not separate and _____ be filtered. However, colloids will scatter light. (_____________) • Example:

Section 2.2 Physical Properties•Physical property- Any characteristic of a

material that can be ______________ without changing the ______________of the substance in the material. ▫Examples: viscosity, conductivity,

malleability, hardness, ____________, boiling point, and____________.

Physical Properties• _________- The tendency of a

liquid to keep from flowing. A resistance to flowing. ▫Example: _______ has a high

viscosity.

• Conductivity- A material’s ability to allow _____ to flow. ▫Example: _________over a stove.

Materials with a high conductivity are called _________. They are also a good conductor of electricity as well. Wood is a _______ conductor.

Physical Properties•Malleability- The ability of a solid to be

_____________________without shattering. ▫Example: Most__________can be made into

coins or foil.

Because gold is both malleable and beautiful, it is often used to make jewelry. These ancient gold medallions were made to form a necklace

Physical Properties• Hardness- One way to compare harness

of two materials is to see which of the materials can _______ the other. Stainless steel knife blades can scratch ______. _______ is the hardest known material.

This Tlingit carver is using an adze to carve a canoe from Western red cedar. Red cedar is a relatively soft wood

Physical Properties• Melting Point- Temperature at which a substance

changes from a ___________. Example: Ice melts because the melting point of water is 0ºC (32ºF).

•  Boiling Point- Temperature at which a substance changes from a _____________or vapor.

The table lists the melting points and boiling points for several substances.

Physical Properties

• Density- ________of the ______ of a substance to its _____. This can be used to test the purity of a substance. ▫Examples: ________ has a density of 10.5

g/cm3.

Using Physical Properties•Physical properties are used to _________ a

material, to _______a material for a specific purpose, or to__________the substances in a mixture. ▫Using properties to identify materials

First, decide which properties to____ Second, do tests on the ________sample Third, compare results with a ______ sample (This is used in crime scene investigations)

▫Using properties to choose materials Properties determine which materials are

_______ for which uses. Example: shoelaces wouldn’t be made from______ wood.

Using Physical Properties▫Using properties to

separate mixtures __________ and __________

are two common separation methods. Filtration- A process that

separates materials based on the _____ of their particles. Example: brewing coffee

Distillation- A process that separates the substances in a solution based on their ________________.

Example: Separate freshwater from seawater.

Recognizing Physical Changes•Physical change- Occurs when some of

the ________ of a material change, but the substances in the material remain the ______. Examples:

Braiding hair and cutting hair are examples of physical changes. Braiding is a reversible change. Cutting cannot be reversed

2.3 Chemical Properties•Chemical property- Any ability to produce

a change on the __________ of matter. •Chemical properties can only be observed

when the substances in a sample of matter are changing into ________________.▫Examples:

Chemical Properties

•Flammability- A material’s ability to ____ in the presence of oxygen. Examples: Anything that can be used as a _____. _______________.

•Reactivity- Describes how readily a substance __________ chemically with other _______. Example: Iron with oxygen and water will form _____ if you leave your bike out in the rain.

Recognizing a Chemical Change•Chemical change- Occurs when a substance

______ and forms one or more ___ substances. Examples: baking cakes, food digesting.

•Three common types of evidence for a chemical change are a change in ______, production of a _____, and formation of a ______________.

Evidence for a Chemical Change

•Color Change▫Silver bracelets will _______. (tarnish)▫Matches _____ and turn ________.▫Copper roofs turn _____.(patina)

Evidence for a Chemical Change•Production of a gas

▫Mixing vinegar with baking soda (_____________ gas)

▫Cakes have gas _______ in it

Evidence for a Chemical Change•Formation of a

precipitate▫Precipitate- _____

form and separate from a _______ mixture

▫_______ of milk- adding lemon juice

Is a Change Chemical or Physical?• Sometimes gas bubbles or color change is not a chemical

change. You must ask yourself: Are _______ substances present ________the change takes place.

• When matter undergoes a chemical change, the ________ of the matter changes. When matter undergoes a physical change, the composition of the matter _______________.

A blacksmith uses a hammer to shape a horseshoe that has been heated. Although the color of the iron horseshoe changes, ______________change is occurring