Vocabulary AP Chem Chapter 1-6

Random Error

An error that has an equal probability of being high or low.

Hypothesis

One or more assumptions put forth to explain the observed behavior of nature.

Model

A set of assumptions put forth to explain the observed behavior of matter. The models of chemistry usually involve assumptions about the behavior of individual atoms or molecules.

Precision

The degree of agreement among several measurements of the same quantity; the reproducibility of a measurement.

Uncertainty

The characteristic that any measurement involves estimates and cannot be exactly reproduced.

Scientific Method

The process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories by experimentation.

Law of Conservation of Mass

Mass is neither created nor destroyed.

Mass

The quantity of matter in an object.

Exponential Notation

Expresses a number as N × 10^M, a convenient method for representing a very large or very small number and for easily indicating the number of significant figures.

SI System

International System of units based on the metric system and units derived from the metric system.

Measurement

(Not explicitly defined in glossary - refers to the process of determining the dimensions, quantity, or capacity of something)

Natural Law

A statement that expresses generally observed behavior.

Theory

A set of assumptions put forth to explain some aspect of the observed behavior of matter.

Weight

The force exerted on an object by gravity.

Dimensional Analysis

(Not explicitly defined as separate entry - see Unit Factor Method)

Accuracy

The agreement of a particular value with the true value.

Significant Figures

The certain digits and the first uncertain digit of a measurement.

Systematic Error

An error that always occurs in the same direction.

Unit Factor Method

An equivalence statement between units used for converting from one unit to another.

Chemical Change

The change of substances into other substances through a reorganization of the atoms; a chemical reaction.

Elements

A substance that cannot be decomposed into simpler substances by chemical or physical means.

Solution

A homogeneous mixture.

Mixtures

(Not explicitly defined in glossary - a combination of two or more substances that are not chemically combined)

Heterogenous

(Spelled as "Heterogeneous" in glossary - see Heterogeneous equilibrium context: involving more than one phase)

Density

A property of matter representing the mass per unit volume.

Compound

A substance with constant composition that can be broken down into elements by chemical processes.

Solid

(Not explicitly defined as standalone - one of the condensed states of matter)

Homogenous

(Spelled as "Homogeneous" in glossary - see Homogeneous equilibrium context: all components in same phase)

Pure Substance

A substance with constant composition.

Physical Changes

A change in the form of a substance, but not in its chemical composition; chemical bonds are not broken in a physical change.

Chromatography

The general name for a series of methods for separating mixtures by using a system with a mobile phase and a stationary phase.

Liquid

(Not explicitly defined as standalone - one of the condensed states of matter)

Paper Chromatography

(Not explicitly defined in glossary - a type of chromatography using paper as the stationary phase)

Filtration

A method for separating the components of a mixture containing a solid and a liquid.

Gas

(Not explicitly defined as standalone - one of the states of matter)

Distillation

A method for separating the components of a liquid mixture that depends on differences in the ease of vaporization of the components.

States

The three different forms in which matter can exist: solid, liquid, and gas.

Matter

The material of the universe.

Atomic Number

the number of protons in the nucleus of an atom.

Law of Multiple Proportions

a law stating that when two elements form a series of compounds, the ratios of the masses of the second element that combine with one gram of the first element can always be reduced to small whole numbers.

Atomic Weights

the weighted average mass of the atoms in a naturally occurring element.

Isotopes

atoms of the same element (the same number of protons) with different numbers of neutrons. They have identical atomic numbers but different mass numbers.

Nucleus

the small, dense center of positive charge in an atom.

Law of Conservation of Mass

mass is neither created nor destroyed.

Cathode-Ray Tubes

the "rays" emanating from the negative electrode (cathode) in a partially evacuated tube; a stream of electrons.

Radioactivity

the spontaneous decomposition of a nucleus to form a different nucleus.

Chemical Bonds

the force or, more accurately, the energy that holds two atoms together in a compound.

Electrons

a negatively charged particle that moves around the nucleus of an atom.

Law of Definite Proportion

a given compound always contains exactly the same proportion of elements by mass.

Avogadro's Hypothesis

equal volumes of gases at the same temperature and pressure contain the same number of particles.

Atomic Masses

the weighted average mass of the atoms in a naturally occurring element.

Nuclear Atom

an atom having a dense center of positive charge (the nucleus) with electrons moving around the outside.

Molecule

a bonded collection of two or more atoms of the same or different elements.

Neutrons

a particle in the atomic nucleus with mass virtually equal to the proton's but with no charge.

Protons

a positively charged particle in an atomic nucleus.

Mass Number

the total number of protons and neutrons in the atomic nucleus of an atom.

Covalent Bonds

a type of bonding in which electrons are shared by atoms.

Acids

a substance that produces hydrogen ions in solution; a proton donor.

Alkali Metals

a Group 1A metal.

Alkaline Earth Metals

a Group 2A metal.

Anion

a negative ion.

Ball-and-stick Model

a molecular model that distorts the sizes of atoms but shows bond relationships clearly.

Binary Compounds

a two-element compound.

Binary Covalent Compounds

(Definition not explicitly provided in glossary, but refers to compounds formed between two nonmetals sharing electrons)

Binary Ionic Compounds

a compound that results when a metal reacts with a nonmetal to form a cation and an anion.

Cation

a positive ion.

Chemical Formula

the representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative numbers of atoms.

Groups/Families

a vertical column of elements having the same valence electron configuration and showing similar properties.

Halogens

a Group 7A element.

Ion

an atom or a group of atoms that has a net positive or negative charge.

Ionic Bonding

the electrostatic attraction between oppositely charged ions.

Ionic Solid

a solid containing cations and anions that dissolves in water to give a solution containing the separated ions, which are mobile and thus free to conduct an electric current.

Metals

an element that gives up electrons relatively easily and is lustrous, malleable, and a good conductor of heat and electricity.

Noble Gases

a Group 8A element.

Nonmetals

an element not exhibiting metallic characteristics. Chemically, a typical nonmetal accepts electrons from a metal.

Oxyanions

(Definition not explicitly provided in glossary as "oxyanions", but refers to polyatomic ions containing oxygen)

Periodic Table

a chart showing all the elements arranged in columns with similar chemical properties.

Periods

(Definition not explicitly provided in glossary, but refers to horizontal rows in the periodic table)

Polyatomic Ions

an ion containing a number of atoms.

Space-Filling Model

a model of a molecule showing the relative sizes of the atoms and their relative orientations.

Structural Formula

the representation of a molecule in which the relative positions of the atoms are shown and the bonds are indicated by lines.

A Mole Ratio

The process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories by experimentation.

Average Atomic Mass

the weighted average mass of the atoms in a naturally occurring element

Avogadro's Number

the number of atoms in exactly 12 grams of pure 12C, equal to 6.022 × 10²³

Balancing a Chemical Equation

(Not explicitly defined in glossary - refers to the process of ensuring equal numbers of each type of atom on both sides of a chemical equation)

Chemical Equation

a representation of a chemical reaction showing the relative numbers of reactant and product molecules

Chemical Stoichiometry

the calculation of the quantities of material consumed and produced in chemical reactions

Conceptual Problem Solving

(Not explicitly defined in glossary - refers to solving problems using understanding of concepts rather than just formulas)

Empirical Formula

the simplest whole-number ratio of atoms in a compound

Limiting Reactant

the reactant that is completely consumed when a reaction is run to completion

Mass Percent

the percent by mass of a component of a mixture or of a given element in a compound

Mass Spectrometer

an instrument used to determine the relative masses of atoms by the deflection of their ions on a magnetic field

Molar Mass

the mass in grams of one mole of molecules or formula units of a substance; also called molecular weight

Mole

the number equal to the number of carbon atoms in exactly 12 grams of pure 12C; Avogadro's number. One mole represents 6.022 × 10²³ units

Molecular Formula

the exact formula of a molecule, giving the types of atoms and the number of each type

Percent Yield

the actual yield of a product as a percentage of the theoretical yield

Products

a substance resulting from a chemical reaction. It is shown to the right of the arrow in a chemical equation

Reactants

a starting substance in a chemical reaction. It appears to the left of the arrow in a chemical equation

Stoichiometric Mixture

quantities of reactants mixed in exactly the correct amounts so that all are used up at the same time

Theoretical Yield

the maximum amount of a given product that can be formed when the limiting reactant is completely consumed