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