Chapter 2 Notes II CHEMICAL AND PHYSICAL CHANGES

PROPERTIES OF MATTER

• What is matter?

• What is mass?

Anything that has mass and takes up space

The amount of matter an object contains

SUBSTANCES

• A substance is matter that has a definite and uniform composition

One type of “stuff”

MIXTURES

• A mixture is a physical blend of two or more substances. They can be physically separated. How?

One type of “stuff” More than one type of

“stuff” together

HETEROGENEOUS vs. HOMOGENEOUS

• There are two different types of mixtures.

• A heterogeneous mixture is one that has more than one phase (part of uniform composition)

• A homogeneous mixture has only one phase.

MIXTURES

Not uniform Uniform throughout

physically

separable

HETEROGENEOUS OR HOMOGENEOUS?

• Saltwater• Spaghetti sauce• Muddy water• Cough syrup• Salad• Brass

TYPES OF SUBSTANCES

• There are two different types of substances:

AND

ELEMENTS

• An element is the simplest forms of matter.

• Each element is represented by a chemical symbol.

COMPOUNDS

• A compound is a substance that can be separated into simpler substances only by chemical means

TYPES OF MATTER

physically

separable

chemically

separable

PHYSICAL PROPERTIES

color odorDensity and

hardness Melting point

Boiling point

solubility

• A quality or condition of a substance that can be observed or measured without changing the substance’s composition

• What are some examples?

STATES OF MATTER

• Matter’s state is a physical property

Definite shape, definite volume

solid

No definite shape, definite volume

liquid

No definite shape, no definite volume

gas

SIDENOTE:

• A gaseous substance that is found as a solid or liquid at room temperature is called vapor.

PHYSICAL CHANGES

• A physical change is one that does not involve altering the chemical composition.

CHEMICAL REACTIONS

• The ability of a substance to react and form new substances is called a chemical property.

• In a chemical reaction, one or more substances change into new substances.

• A reaction starts with the reactants, and the substances formed are called products.

4 CLUES TO CHEMICAL REACTION

Color

change Gas

formed

Heat/light

produced/

absorbed

Solid from

a liquid

CHEMICAL OR PHYSICAL CHANGE?

• Baking cookies• Boiling water• Dissolving salt• Burning firewood• Milk spoiling• Metal rusting• Tearing paper• Melting ice

LAW OF CONSERVATION OF MASS

• During any chemical reaction, the quantity of matter is unchanged. The mass of the products always equals the mass of the reactants.