Chem Unit 1

Chemistry

The study of the composition, properties, and interactions of matter

Hypothesis

A tentative explanation of observations that acts as a crude for gathering/checking information

The Laws of Science

Summarize a wast number of experimental observations and describe/predict some facet of the natural world

Scientific Theories

Well sustained, comprehensive, testable explanations of particular aspects of nature

Are accepted because they provide satisfactory explanations, but can change if new data becomes available

The Scientific Method

Includes:

1. An observation/curiosity

2. Forming of a hypothesis

3. Preform an experiment and make observations

4. Experiment contributes to body of knowlodge

5. If more testing supports hypothesis; hypothesis becomes theory

6. If more testing yields content observations; observations become law

7. If results are inconsistent with prediction; form a new hypothesis (back to the drawing board)

Macroscopic domain

The realm of everyday things that are large enough to be sense directly by human touch/sight

Includes things we observe/measure physically and chemically

Microscopic domain

The realms of objects and events that can’t be seen by the naked eye and require a microscope

Includes biological cells, molecules, and atoms

Symbolic domain

Specialized language used to represent components of the Macro. and Micro. domain

Help interpret behavior of Macro. domain in terms of the components of the Micro. domain

Includes periodic table symbols, chemical formulas, chemical equations, graphs, drawings, calculation, etc.

Matter

Anything that occupies space and has mass; Includes solids, liquids, gases, and plasma

Solid

A form of matter that is rigid and possesses a definite shape

Liquid

A from of matter that flows and takes the shape of its container, except when it forms a flat/slightly curved upper surface

Gas

A form of matter that takes both the shape and volume of its container

Plasma

A gaseous state of matter that contains appreciable numbers of electrically charged particles

Occurs naturally in stars; most common matter in the universe

Mass

The measure of the amount of matter in an object; can be measure by amount of force used to move an object

Weight

The force gravity exerts on an object; weight changes when gravity changes, mass doesn’t

The Law of Conversion of Matter

“There is no detectable change in the total quantity of matter present when matter covers from one type to another (a chemical change) or changes around solid, liquid, or gaseous states (a physical change)

Pure substance

Has constant composition; all specimens of a pure substance have exactly the same makeup and properties

Divided into elements and compounds

Elements

Pure substances that can’t be broken down into simpler substances by chemical change

Compounds

Pure substances that consist of 2 or more elements

Mixture

Composed of 2 or more types of matter, can be present in varying amounts and can be separated by physical changes (ex: vaporation, etc.)

Divided into heterogenous and homogenous mixtures

Heterogenous mixture

A mixture with a composition that varies point to point

Homogenous mixture (solution)

A mixture that has a uniform composition and appears visually the same throughout

Atom

The smallest particle of an element that has the properties of that element and can enter into a chemical combination; stems from Greek word atoms, meaning indivisible

Molecule

2 or more atoms connected by chemical bonds

Physical property

Characteristic of matter that isn’t associate with a change in it’s chemical composition (density, color, etc.)

Physical change

A change in the state/properties of matter without Anya accompanying change in the chemical identities of the substances contained in the matter (wax melting, sugar dissolving in liquids, etc.)

Chemical property

The ability/inability to change from one matter to another (flammability, toxicity, acidity, other react ability)

Chemical change

Always produces one or more types of matter that differ from the matter present before the change

Extensive property

Depends on the amount of matter present (mass, volume, etc.)

Intensive property

Doesn’t depend on amount of matter present (temperature, etc.)

Scientific/Exponential notation

Simplified large numbers (298,000=10^5)

Units

Standards of comparison for measurements (lbs., cm., mL., etc.)

International system of units/SI units

Units that are fixed by international agreement, established during the French Revolution

Includes:

Length (meters m)

Mass (kilogram kg)

Time (second s)

Temperature (kelvin K)

Exact number

A value known with complete certainty and zero uncertainty (1 ft. - 12 in., there are 12 people in the room, etc.)

Uncertainty

The estimated range of values around a (lab) measurment