U N I T 2 . 1

Matter and Change

Chemistry

Chemistry is the study of the composition, structure, and properties of matter and the changes it undergoes.

Matter is anything that has mass and takes up space. Examples: desk, book, air, water Non examples: energy, electricity

Elements

An element is a pure substance made of only one kind of atom.

Everything is made from a combination of elements.

Each element has characteristic properties.

Each element has a symbol Hydrogen H sodium Na (first letter must be caps, 2nd lower case)

Periodic table

The periodic table organizes the elements so they are grouped into similar properties.

Mendeleev was the first scientist to put together a periodic table.

Periodic

Metals are shown on the left side of the periodic table. (exception: hydrogen) - Properties of metals: malleable, ductile, metallic luster, most are solids at room temperature. -Good conductors of heat and electricity Nonmetals are shown on the right side of the table. -Properties of nonmetals: solids are brittle - Poor conductors of heat and electricity Metalloids are the elements along the zig zag line between metals and nonmetals. (exception: Aluminum) -Has some characteristics of metals and some of nonmetals -Tend to be semiconductors of heat and electricity

A vertical column is called

a group or family. These elements react similarly

A horizontal row is called a period.

The periodic table

Names of groups

Group 1: alkali metals (except Hydrogen) Most reactive metals

Group 2: alkaline earth metals Group 3-12: transition metals Group 17: halogens Most reactive nonmetals

Group 18: noble gases Very stable, these do not bond naturally

UNIT 2.2

Matter and Change

The Organization of Matter

Matter

Mixtures: a) Homogeneous (Solutions) b) Heterogeneous

Pure Substances

Compounds Elements

Atoms

Nucleus Electrons

Protons Neutrons

Quarks Quarks

Pure Substances Each have a fixed composition Each a unique set of properties

Elements – a type of matter that cannot be broken down into two or more

pure substances

Compounds – A pure substance that contains two or more elements that are

chemically bonded. (properties are different than the elements that make it up)

Mercury,Hg

Chlorine gas, Cl2

Sodium metal, Na

Sodium Chloride, NaCl

Silver metal, Ag

Water, H2O

Separation of a Compound The Electrolysis of water

Compounds must be separated by chemical means. With the application of electricity, water can be separated into its elements

Mixtures

Contain two or more substances mixed together physically and combine in such a way that each substance retains its chemical identity. There is not a fixed composition. Homogeneous

Uniform mixture in which the composition is the same throughout.

Heterogeneous Not uniform, different in composition throughout.

Granite

Heterogeneous

Brass

Homogeneous

Copper Sulfate, heterogeneous

Mixtures can be separated.

By physical means only! Filtration Distillation Magnetic properties Chromatography evaporation Many more

Types of matter can be classified quickly using this chart and remembering what each is.

Phase Differences

Solid – definite volume and shape; particles packed in fixed positions. Liquid – definite volume but indefinite shape; particles close together but not in fixed positions Gas – neither definite volume nor definite shape; particles are at great distances from one another Plasma – high temperature, ionized phase of matter as found on the sun.

U N I T 2 . 3

Matter and Change

Properties of Substances

Chemical properties Observed when substances take part in a chemical reaction –

A change that converts it to a new substance.

Physical properties Observed without changing the chemical identity of a substance.

Melting point Boiling point Color Texture Density others

Properties of Gold are:

Physical: Melting point of 1063 oC (intensive)

Color gold (intensive)

Amount in weight (extensive)

Chemical: Gold can be stored in air without reacting chemically with oxygen

Changes in Matter

Matter can undergo physical and chemical changes Physical changes A change in a substance that does not involve a change in the

identity of the substance. Cutting, tearing, mixing Change of states (boiling, melting, freezing, etc.)

Chemical changes (chemical reaction) A change in which one or more substances are converted into

different substances. Iron rusting, milk going sour, a log burning

Chemical changes

Chemical changes can be observed by -a color change -a change in temperature -production of a gas (you’ll see bubbles)

-formation of a precipitate ( a solid forms from two liquids)