Chem Midterm - Chapters 1-3 Vocabulary

Scientific Method

A systematic approach and organized process used in scientific study to do research. It allows scientists to verify the works of others

Hypothesis

A tentative explanation for what has been observed in an experiment

Experiment

A set of controlled observations that test a hypothesis

Theory

An explanation of a natural phenomenon based on many observations and investigations

Scientific Law

A relationship in nature that is supported by many experiments

Independent Variable

The variable that you plan to change in an experiment

Dependent Variable

The variable that responds to the change in the independent variable

Scientific Notation

Expressing any number as a number between 1 and 10 multiplied by 10 raised to a power

Significant Figures

All known digits plus one estimated digit

Accuracy

How close a measured value is to an accepted value

Precision

refers to how close a series of measurements are to one another

Certainty

All numbers that are known

Unit Analysis

Proportional reasoning where a given measurement can be multiplied by a known proportion to give a result with a different unit or dimension

Conversion Factor

A ratio of equivalent values having different units

Law of Definite Proportions

A compound is always composed of the same elements in the same proportion by mass, no matter how large or small the sample is

Density

A ratio that compares the mass of an object to its volume

Substance

A matter that has a definite and uniform composition (also known as a chemical)

Matter

Anything that has mass and takes up space

Element

A pure substance that cannot be separated into simpler substances by physical or chemical means

Compound

A substance made up of two or more different chemical elements combined in a fixed ratio

Physical Property

A characteristic that can be observed/measured without changing the sample’s composition

Extensive Property

A characteristic that is dependent on the amount of a substance present

Intensive Property

A characteristic that is independent of the amount of a substance present

Chemical Property

The ability of a substance to combine with or change into one or more substances

States of Matter

The classification of all matter that exists naturally

Solid

A form of matter that has its own definite shape and volume

Liquid

A form of matter that flows, ahs constant volume, and takes the shape of its container

Gas

A form of matter that not only flows to conform to the shape of its container but also fills the entire volume of its container

Vapor →The gaseous state of a substance that is a solid or liquid at room temperature

Physical Change

A change that alters a substance without changing its composition

Chemical Change

A process that involves one or more substances changing into new substances

Law of Conservation of Mass

Mass is neither created nor destroyed during a chemical reaction (it is conserved)