Matter and ChangeChapter 2

Properties of Matter• Matter is anything that has a mass and takes up

space.

• Mass—is a measure of the amount of matter the object contains.• The properties of matter describe the characteristics and

behavior of matter, including the changes that matter undergoes.

• Describes an object’s action and it’s state and any changes it undergoes. • Ex: helium is a gas, it tends to float and explode

Identifying Substances• Substance—matter that has a uniform and

definite composition.

• Pure Substance—substance that has identical intensive properties because every sample has the same composition.• Ex: gold and copper

• Physical properties—a quality or condition of a substance that can be observed or measured without changing the substance’s composition.• Ex: hardness, color, conductivity, and malleability

States of Matter• 3 states of matter• Solids• Liquids• Gases

Solids• A form of matter that has definite shape and

volume.• The shape of the solid does not depend on the shape of

the container.

• Key Characteristics• Definite shape• Definite volume• Not easily compressed

Liquids• A form of matter that has indefinite shape, flows,

and has a fixed volume.

• Key Characteristics• Indefinite shape• Definite volume• Not easily compressed

Gas• A form of matter that takes both the shape and

volume of its container.

• Key Characteristics• Indefinite shape• Indefinite volume• Easily compressed

Physical Changes• Physical change—when some properties of the

material changes, but the composition of the material does not change.

• 2 categories to classify physical changes• Reversible • irreversible

Physical Changes cont’• Examples of physical changes include: • Boiling,• Freezing,• Evaporating,• Melting,• Dissolving,• And crystallizing

Mixtures• Mixture—physical blend of two or more components.

• 2 classifications of mixtures• Heterogeneous mixture—a mixture in which the composition is

not uniform.• Ex: chicken noodle soup

• Homogeneous mixture—a mixture in which the composition is uniform.• AKA Solution

• Phase—any part of a sample with uniform composition and properties.• Homogeneous mixture has a single phase.• Heterogeneous mixture has multiple phases.

Separating Mixtures• Filtration—process that separates a solid from the

liquid in a heterogeneous mixture.

• Distillation—process that separates one liquid from another.• Boil the liquid to produce a vapor that is then condensed

to a liquid.

• Alloys are solid solutions that contain different metals and sometimes nonmetallic substances.

Solutions• When you dissolve sugar in water, sugar is the

solute—the substance being dissolved. • The substance that dissolves the solute, in this

case water, is the solvent. • When the solvent is water, the solution is called

an aqueous solution.

Elements and Compounds• Element—the simplest form of matter that has a

unique set of properties.

• Compound—is a substance that contains two or more elements chemically combined in a fixed proportion.• Ex: Carbon, oxygen, and hydrogen combine to form

sucrose.

Symbols & Formulas• Symbols for elements are based on the Latin

names for the elements.• System was developed by Swedish Chemist Jons Jacob

Berzelius (1779-1848)

• Each element is represented by one or two-letter chemical symbol.• Ex: H—Hydrogen, Au—Gold (table 2.2 pg 52)

Two Types of Substances • Of the known elements, only about 90 occur

naturally on Earth. The remainder are synthesized, usually in barely detectable amounts, in high-energy nuclear experiments.

• Less than half of the 90 naturally occurring elements are abundant enough to play a significant role in the chemistry of everyday stuff.

Organizing the Elements• The periodic table organizes elements in a way

that provides a wealth of chemical information—much more than is evident to you now. It shows the chemical symbols for the elements.

• Their symbols usually correspond to their names in Latin.

Compounds Are More Than One Element

• A more complete definition is that a compound is a chemical combination of two or more different elements joined together in a fixed proportion with a unique set of chemical and physical properties.

• More than 10 million compounds are known and the number keeps growing.

• Some new compounds are discovered and isolated from natural chemical sources such as plants and colonies of bacteria and are synthesized in laboratories for many different uses.

Suspensions & Colloids• Suspension—is a heterogeneous mixture that

separates into layers over time.

• Colloid—contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension.• Colloids do not separate into layers.

Examples of Physical Properties• Physical property—is any characteristic of a

material that can be observed or measured without changing the composition of the substances in the material.• Examples of physical properties• Viscosity• Conductivity• Malleability• Hardness• Melting point • Boiling point• Density

Physical Properties cont’• Viscosity—the tendency of a liquid to keep from

flowing; resistance to flowing.

• Conductivity—a material’s ability to allow heat or electric charges to flow.

• Malleability—the ability of a solid to be hammered without shattering.

• Hardness of a substance is determined by seeing which of the materials can scratch the other.

Physical Properties cont’• Melting point—temperature at which a substance

changes from solid to liquid.

• Boiling point—temperature at which a substance boils.

• Density—is the ratio of the mass of a substance to its volume.• Used to test the purity of a substance.

Assignment• Section 2.2 Assessment• Reviewing Concepts• #1-6

Chemical Properties• Chemical Properties—is any ability to produce a

change in the composition of matter.

• 2 examples of chemical properties:• Flammability• Is a material’s ability to burn in the presence of

oxygen.• Reactivity • How readily a substance combines chemically with

other substances.

Chemical Change• Chemical change—occurs when a substance

reacts and forms one or more new substances.

• 3 common types of evidence for a chemical change:• Change in color• Production of a gas• Formation of a precipitate

Assignment• Reviewing Content• #1-10

• Understanding Concepts• #11-16