Matter

Anything that has mass and takes up space

Gram

The metric unit of mass

Mass

A measure of the amount of matter in an object

Liter

A metric unit of volume

Meter

The metric unit of length

Newton

The metric unit of force

Slug

The English unit of mass

Factor-label method

A method of conversion using the multiplication of fractions

Derived unit

A unit formed by the multiplication and/or division of other units

Graduated cylinder

A device used for measuring the volume of liquids

Meniscus

The curved surface of a liquid, typically in a glass container

Accuracy

An indication of how close a measurement is to the true value.

Precision

An indication of the scale on the measuring device that was used

Significant figure

A digit in a measurement that is either non-zero, a zero that is between two significant figures, or a zero at the end of the number and to the right of the decimal

Density

An object's mass divided by the volume that the object occupies

Energy

The ability to do work

Work

The force applied to an object times the distance that the object travels parallel to that force

Heat

Energy that is transferred as a consequence of temperature differences

Hypothesis

An educated guess that attempts to explain observations

Scientific law

A description of the natural world that has been confirmed by an enormous amount of data

Theory

A hypothesis that has been confirmed by experimental data

Joule

The metric unit for energy

Kinetic energy

Energy that is in motion

Potential energy

Energy that is stored

The First Law of Thermodynamics

Energy cannot be created or destroyed. It can only change form.

Celsius

A temperature scale defined so that water freezes at 0 and boils at 100

Fahrenheit

A temperature scale defined so that water freezes at 32o and boils at 212o

Kelvin

The absolute temperature scale: It is not possible to reach or go below 0 Kelvin.

Calibration

The process of using certain physical measurements to define the scale of a measuring device

Absolute temperature scale

The Kelvin temperature scale: It is not possible to reach or go below 0 Kelvin.

Calorie (cal)

The amount of heat necessary to warm one gram of water one degree Celsius

Food calorie (Cal)

1,000 chemistry calories (cal)

Specific heat

The amount of heat necessary to raise the temperature of 1 gram of a substance by 1 degree Celsius

Calorimetry

An experimental process that measures the heat released or absorbed during a chemical or physical change

Calorimeter

An experimental device that measures the heat released or absorbed during a chemical or physical change

Continuous theory of matter

The idea that substances are composed of long, unbroken blobs of matter

Discontinuous theory of matter

The idea that substances are composed of tiny, individual particles like grains of sand

The Law of Mass Conservation

Matter cannot be created or destroyed; it can only change forms.

Decomposition

The process by which a substance is broken down into its constituent elements

Element

Any substance that cannot be decomposed into less massive substances

Metal

An element that tends to give up its electrons. Metals are found on the left side of the jagged line on the Periodic Table of Elements, with the exception of hydrogen.

Nonmetal

An element that tends to take electrons from other elements. Non-metals are found on the right side of the jagged line on the Periodic Table of Elements. Hydrogen is also a non-metal, even though it is on the left side of the jagged line.

Compound

A substances that can be decomposed into elements by chemical means

The Law of Definite Proportions

The proportion of elements in any compound is always the same.

Dimensionless quantity

A quantity with no units

The Law of Multiple Proportions

If two elements combine to form different compounds, the ratio of masses of the second element that react with a fixed mass of the first element will be a simple, whole-number ratio.

Atom

The smallest chemical unit of matter

Molecule

More than one atom bound together to form a compound

Chemical formula

A notation that indicates the number of type of each element in a compound

Chemical symbol

An abbreviation for an element

Covalent compound

A compound formed by atoms that share electrons

Ionic compound

A compound formed by ions

Mixture

A substance that contains different compounds and/or elements

Pure substance

A substance that contains only one element or compound

Heterogeneous mixture

A mixture with a composition that is different depending on what part of the sample you are observing

Homogeneous mixture

A mixture with a composition that is always the same no matter what part of the sample you are observing

Chemical change

A change that affects the type of molecules or atoms in a substance

Physical change

A change in which the atoms or molecules in a substance stay the same

Boiling

The process by which a substance changes from its liquid phase to its gas phase

Condensing

The process by which a substance changes from its gas phase to its liquid phase

Freezing

The process by which a substance changes from its liquid phase to its solid phase

Melting

The process by which a substance changes from its solid phase to its liquid phase

Phase

One of three states of matter: solid, liquid, or gas

Phase change

The process by which a substance changes from one phase (solid, liquid, or gas) to another phase (solid, liquid, or gas)

Kinetic Theory of Matter

The theory that the atoms or molecules which make up a substance are in constant motion, and the higher the temperature, the greater their speed

Melting point

The temperature at which a substance changes from its solid phase to its liquid phase

Chemical equation

A representation of a chemical reaction

Chemical reaction

A process by which one or more substances change into one or more different substances

Homonuclear diatomic

A molecule composed of two identical atoms

Products

The substances found on the right side of a chemical equation

Reactants

The substances found on the left side of a chemical equation

Sublimation

The process by which a solid turns directly into a gas, without going through the liquid phase

Decomposition reaction

A reaction that changes a compound into its constituent elements

Formation reaction

A reaction that starts with two or more elements and produces one compound

Complete combustion reaction

A reaction in which O2 is added to a compound containing carbon and hydrogen, producing CO2 and H2O

Incomplete combustion reaction

A reaction in which O2 is added to a compound containing carbon and hydrogen, producing either CO or C, along with H2O

Catalytic converter

A device on an automobile that converts gaseous carbon monoxide produced by the engine into gaseous carbon dioxide

Atomic mass

The number on the periodic chart that is below an element's symbol. It represents the average mass of the atom's isotopes in atomic mass units.

Atomic number

The number on the periodic chart that is above an element's symbol. It represents the number of protons in the nucleus of the atom.

Atomic mass units

The mass unit used on the periodic chart: 1.00 amu = 1.66 x 10-24 g

Molecular mass

The mass of a single molecule

Mole

A group of atoms or molecules that number 6.02 x 1023

Avogadro's number

The number of molecules or atoms in a mole: 6.02 x 1023

Stoichiometry

The process by which the amount of one substance in a chemical reaction is related to the amount of another substance in a chemical reaction

Limiting reactant

The reactant that runs out first in a chemical reaction. It determines the amount of products made.

Excess reactant

The reactant or reactants that are left over at the end of a chemical reaction

Stoichiometric coefficients

The numbers that appear to the left of the chemical formulas in a chemical equation. They represent the number of moles of each substance.

Gay-Lussac's Law

The stoichiometric coefficients in a chemical equation relate the volumes of gases in the equation as well as the number of moles of substances in the equation.

Empirical formula

A chemical formula that tells you a simple, whole-number ratio for the atoms in a molecule

Molecular formula

A chemical formula that provides the number of each type of atom in a molecule

Molar mass

The mass of one mole of a given compound

Crookes tube

An experimental apparatus developed by William Crookes. It consists of a glass tube filled with a small amount of gas. Electrodes in the tube allow for the passage of electricity through the gas.

Cathode ray tube

Another name for a Crooke's Tube

Electron

One of the three particles that make up the atom. It is negatively charged and orbits the nucleus of the atom

Neutron

One of the three particles that make up the atom. It is electrically neutral and is in the nucleus of the atom

Proton

One of the three particles that make up the atom. It is positively charged and is in nucleus of the atom

Isotopes

Atoms with the same number of protons but different numbers of neutrons

Mass number

The total number of neutrons and protons in an atom

Isotopic enrichment

The process by which the abundance of one isotope in an element is increased. This is typically used in order to make the fuel for nuclear bombs.

Model

A constructed image of something that we cannot see with our eyes

Plum pudding model

A model that said the atom is made of a positive gel (the pudding) with negative particles (the plums) suspended in the gel

Planetary model

Another name for the Rutherford model

Rutherford model

A model that said the atom is made of a dense, postively-charged nucleus with electrons orbiting the nucleus in circles

Nucleus

The center of the atom that contains the neutrons and protons

Particle/Wave Duality Theory

The theory that light sometimes behaves as a particle and sometimes behaves as a wave

Photon

A "particle" of light

Amplitude

A measure of the height of the crests or the depths of the troughs on a wave

Wavelength

The distance between the crests (or troughs) of a wave

Visible spectrum

The range of light wavelengths that are visible to the human eye

Physical constant

A measurable quantity in nature that does not change

Frequency

The number of wave crests (or troughs) that pass a given point each second

Electromagnetic spectrum

The total range of wavelengths of light that come from the sun

Electromagnetic radiation

Another term for light, including all wavelengths, both visible and not visible

Planck's constant

The physical constant that relates the energy of light to its frequency

Cones

The cells on the eye's retina that detect different energies of light. These cells are responsible for our ability to see colors.

Rods

The cells on the eye's retina that detect low levels of light

Spectrometer

A device that analyzes light emitted or absorbed by a substance

Spectroscopy

The process by which individual wavelengths of light emitted by a substance are analyzed. This process can be used to identify the elements in a substance.

Quantum assumption

The assumption that a physical quantity (such as energy) cannot have any value, but is restricted to have only discrete values

Orbital

A specific shape that confines the position of an electron relative to the nucleus

Quantum mechanical model

The modern-day model of the atom in which electrons whirl around the nucleus in various paths called "orbitals."

Ground state

The lowest possible energy state for a given substance

Electron configuration

A notation that lists the number of electrons that occupy each orbital in an atom

Valence electrons

The electrons that exist farthest from an atom's nucleus. They are generally the electrons with the highest energy level number.

Lewis structure

A schematic representation of the valence electrons in an atom or molecule

Octet rule

Most atoms strive to attain eight valence electrons.

Electron-dot diagram

Another name for a Lewis structure

Ion

An atom that has gained or lost electrons and thus has become electrically charged

Transition metal

An element that rests in the "d-orbital" block of the Periodic Table of Elements

Ionization

The process by which an atom turns into an ion by gaining or losing electrons

Ionization potential

The amount of energy needed in order to take an electron away from an atom

Periodic property

A characteristic of atoms that varies regularly across the periodic chart

Electronegativity

A measure of how strongly an atom attracts extra electrons to itself

Atomic radius

The average radius of an atom

Covalent bond

A shared pair of valence electrons that holds atoms together in covalent compounds

Double bond

A total of four electrons shared between atoms

Triple bond

A total of six electrons shared between atoms

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