Matter and Change

Introduction to Chemistry

Chemistry is a physical science.Chemistry is the study of the composition,

structure, and properties of matter and the changes that matter undergoes.

Chemistry contributes to other natural sciences including biology, geology, and physics.

Chemistry overlaps into the areas of agriculture, medicine, and a variety of manufacturing industries.

Branches of ChemistryOrganic chemistry Inorganic chemistry Physical chemistryAnalytical chemistryBiochemistryTheoretical chemistry

ChemistryBasic research accumulates knowledge for

its own sake. It is a branch of pure science.Applied research focuses on problem

solving.Technological development involves the

production and use of products that improve our quality of life.

Is

End of Section 1.1

Alchemy and the Birth of Chemistry

Chemistry was around before people acknowledged it as a science.

Greek philosophers began to question the structure and behavior of matter by using logic. Atomists Aristotlians

Alchemists had the goal of turning common metals into gold. This process was called transmutation.

Alchemy and the Birth of ChemistryRoger Bacon believed that experimentation was

the key to understanding but that idea was not popular until the 17th century when Robert Boyle emphasized it.

Lavoisier introduced measurement and is called the founder of modern chemistry for this reason.

Henri Becquerel and Marie Curie made discoveries that revived the idea of transmutation.

Matter

Matter is anything that has mass and takes up space.

Mass is the amount of matter that an object or substance possesses.

Space is also known as volume.

MatterMatter is composed of atoms, which are the

smallest particles of matter which retain the identity of the matter.

There are two major classes of matter.

Two Classes of Matter Pure Substances

Uniform composition Definite composition Homogeneous Identical properties Cannot be separated and

maintain its identity

Mixtures Physical

combination(blend) of two or more substances

Separable by physical means

Variable composition Components retain their

properties

Two Kinds of Mixtures Homogeneous

Also called a solution Physical combinations Uniform throughout a given

sample Components uniformly

distributed Composition may vary

from sample to sample Separable by physical

means

Heterogeneous Physical combinations Nonuniform within a

sample Components are

distinguishable Separable by physical

means

Two Kinds of Substances Elements

All samples are identical.

Approximately 120 Approximately 90 are

naturally occurring May be metal,

metalloid, or nonmetal Exist as solids, liquids,

or gases

Compounds All samples are identical. Chemical combinations Cannot be physically separated

and keep identity. New properties that are different

from component properties Definite composition Homogeneous Can be broken into elements by a

chemical change.

End of Section 1.2

Elements Elements are summarized on the Periodic Table. They are represented by symbols of 1, 2, or 3 letters. The vertical columns are groups or families whose

members have similar properties. The horizontal rows or periods have members whose

properties change regularly as one moves from left to right.

All elements may be classified as representative (Gps 1-2 and 13-18) or transition (Gps 3-12).

The lanthanides and actinides are the lower transition elements.

Metallic ElementsConduct heat and electricity.Are malleable.Are ductile.Have luster.Are solids, except for mercury which is a liquid.Have high tensile strength.Are found on the left side of the zig zag line on the

Periodic Table.

Nonmetallic ElementsDo not conduct well.Are brittle.Are dull in color.May be gases or solids, except bromine which is a

liquid.Are found on the right side of the zig zag line on

the Periodic Table.

Elemental AbundanceThe most abundant element in the Earth’s crust is

oxygen. (Si, Al, Fe, Ca)The most abundant metal in the Earth’s crust is

aluminum.The most abundant element in our atmosphere is

nitrogen. (O2, Ar) The most abundant element in our universe is

hydrogen. The most abundant element in the human body is

oxygen.(C, H2)

Properties of Matter Physical properties are those which can be

observed or measured without causing a substance to change its identity. A new substance is not formed. A physical change occurs. It is easily reversible.

Some examples of physical properties are form, color, size, smell, melting point and conductivity.

There are two types of physical properties: extensive and intensive.

Extensive properties are those dependent upon amounts present.

Intensive properties are all others.

Properties of Matter Chemical properties are those which cause a substance to

change its features into something else. A new substance is formed when a chemical property is observed. A chemical change occurs in which one or more substances are converted into something new.

There are several evidences that a chemical change has occurred. They may include large energy change, evolution of gas, change in color, formation of a precipitate, odor change and difficulty of reversal.

In a chemical reaction the starting substances are called reactants while the ending substances are called products.

Changes Matter Undergoes Physical changes are those in which the matter

maintains its identity but may be changed in form, color, temperature, mass or some other easily reversible way.

Chemical changes are those in which the identity of the matter and, hence its properties, is changed into another kind of matter.

End Section 1.3

Forms of Matter

SolidsDefinite volume, shapeUsually high densityAlmost incompressibleExpand only slightly when heatedTrue solids have definite melting points.True solids break along a face; they do not shatter.

Forms of MatterLiquidsDefinite volumeTake shape of containerExperience flowAlmost incompressibleLess dense than solid formExpand slightly when heatedMaintain horizontal surface

Forms of MatterGasesNo definite volume or shape.Volume depends on temperature and pressure.Very compressible.Less dense than the liquid formExperience flowVery large spaces between the particles.High energy form of matter.

Forms of Matter Plasma is a high temperature physical state of matter in

which atoms lose their electrons and become ionized. The sun is a good example of a plasma as is a fluorescent bulb.

Bose-Einstein Condensate(BEC) Newest form of matter Occurs at very low temperatures Easiest to make with Group IA elements Called “fuzzy matter”

State Changes are physical changes.When one form of matter changes into another

form of matter, a state ,or phase, change occurs. Solid to liquidLiquid to gasSolid to gasLiquid to solidGas to liquidGas to solid

End Section 1.4