Chem 20 Review Unit 1

Alberta Chem 20 Unit 1 terms

Science

The study of the natural and technological world to describe, explain, and predict substances and charges.

Chemistry

The physical science that deals with the composition, properties, and changes in matter; the study of chemicals and their reactions, associated technologies, and environmental effects.

Empirical knowledge

Knowledge gained through observations.

Generalizations

Statements that summarize a limited number of empirical results.

Scientific Law

A major empirical concept that is based on a large body of empirical knowledge.

Empirical Hypotheses

Preliminary generalizations regarding observable properties that require further testing.

Empirical Definitions

Statements that define an object or a process in terms of observable properties.

Theoretical Knowledge

Knowledge that explains the unobservable through scientific observation.

Matter

Anything that has mass and occupies space; may be a pure substance or a mixture.

Pure Substances

Matter whose composition is constant and uniform; composed of only one kind of chemical.

Mixture

Matter whose composition includes two or more substances and may or may not be uniform throughout the sample.

Elements

Pure substances that cannot be broken down into simpler chemical substances by only physical or chemical means; consist of only one kind of atom.

Compounds

Pure substances that can be separated into their elements by heat or electricity; substances containing atoms/ions of more than one element in a definite fixed proportion.

Atom

The smallest entity of an element that is still characteristic of that element.

Periodic Law

The observation that chemical and physical properties of elements repeat themselves at regular intervals.

Metal

An element that is shiny, bendable, and a good conductor of electricity.

Nonmetal

An element that is not shiny, not bendable, and generally not a good conductor of electricity.

Semimetals

A class of elements that are distributed along the "staircase line" in the periodic table; also called metalloids.

Alkali metals

Soft, silver-colored metals that react violently with water; Group 1 elements.

Alkaline-earth metals

Light, reactive metals that form an oxide coating when exposed to air; Group 2 elements.

Halogens

Reactive nonmetal elements from Group 17.

Noble gases

Very unreactive gaseous elements from Group 18; elements with a full shell of valence electrons.

Theory

A concept or set of ideas that explains a larger number of observations in terms of non-observables.

Mass Number

The sum of protons and neutrons in the nucleus of an atom or nonatomic ion.

Atomic Number

The characteristic number of protons in the nucleus of an atom of a particular element.

Ion

An entity with a net positive or negative electrical charge due to the loss or gain of one or more electrons.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Ionic compound

A pure substance formed from a metal and a nonmetal.

Molecular compound

A pure substance that may be a solid, liquid, or gas at SATP; consists of covalently bonded nonmetal atoms.

Acid

A compound that forms electrically conducting aqueous solutions that turn blue litmus red, neutralize bases, and react with active metals to produce hydrogen gas.

Aqueous Solution

A homogeneous mixture of one or more solutes dissolved in water.

Polyatomic Ion

A group of atoms with a net positive or negative charge on the whole group.

Hydrate

A pure substance that decomposes at a relatively low temperature to produce water and other substances; a substance containing loosely bonded water molecules.