CHE 103 FINAL

Matter

Anything that has mass and volume.

Mass

Amount of matter in an object.

Volume

Amount of space occupied by matter.

Element

Pure substance made of one type of atom.

Compound

Substance made of two or more elements chemically bonded.

Molecule

Two or more atoms bonded together.

Mixture

Physical combination of substances.

Homogeneous mixture

Mixture with uniform composition throughout.

Heterogeneous mixture

Mixture with nonuniform composition.

Physical property

Characteristic observed without changing chemical identity.

Chemical property

Characteristic describing ability to undergo chemical change.

Physical change

Change that does not alter chemical identity.

Chemical change

Change producing new substances.

Accuracy

How close a measurement is to the true value.

Precision

How close repeated measurements are to each other.

Dimensional analysis

Method using conversion factors to solve problems.

Significant figures

Digits considered meaningful in a measurement.

Scientific notation

Method of expressing numbers using powers of ten.

Solid

State of matter with fixed shape and fixed volume.

Liquid

State of matter with variable shape and fixed volume.

Gas

State of matter with variable shape and variable volume.

Kinetic molecular theory

Theory stating particles are constantly moving.

Atom

Smallest unit of an element retaining its properties.

Proton

Positively charged particle in nucleus.

Neutron

Neutral particle in nucleus.

Electron

Negatively charged particle outside nucleus.

Atomic number

Number of protons in an atom.

Mass number

Total number of protons and neutrons.

Isotope

Atoms of same element with different numbers of neutrons.

Ion

Charged atom or molecule.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Metal

Element that tends to lose electrons and conduct electricity.

Nonmetal

Element that tends to gain electrons and is a poor conductor.

Metalloid

Element with properties between metals and nonmetals.

Alkali metals

Highly reactive Group 1 metals.

Alkaline earth metals

Reactive Group 2 metals.

Halogens

Reactive Group 17 nonmetals.

Noble gases

Mostly unreactive Group 18 gases.

Diatomic elements

H2, N2, O2, F2, Cl2, Br2, and I2.

Polyatomic ion

Charged group of covalently bonded atoms.

Ammonium

NH4+ polyatomic ion.

Nitrate

NO3− polyatomic ion.

Sulfate

SO4^2− polyatomic ion.

Hydroxide

OH− polyatomic ion.

Carbonate

CO3^2− polyatomic ion.

Mole

Amount of substance containing 6.022 × 10^23 particles.

Avogadro’s number

6.022 × 10^23 particles per mole.

Molar mass

Mass of one mole of a substance.

Empirical formula

Simplest whole-number ratio of atoms.

Molecular formula

Actual numbers of atoms in a compound.

Solution

Homogeneous mixture.

Solute

Substance dissolved in a solution.

Solvent

Substance doing the dissolving.

Aqueous solution

Solution in which water is the solvent.

Molarity

Moles of solute per liter of solution.

Percent composition

Percent by mass of each element in a compound.

Chemical equation

Representation of a chemical reaction.

Reactants

Starting substances in a reaction.

Products

Substances produced in a reaction.

Coefficient

Number placed before a chemical formula.

Law of conservation of mass

Matter is neither created nor destroyed.

Synthesis reaction

Reaction where substances combine.

Decomposition reaction

Reaction where a compound breaks apart.

Single replacement reaction

Reaction where one element replaces another.

Double replacement reaction

Reaction involving exchange of ions.

Combustion reaction

Reaction with oxygen producing heat.

Stoichiometry

Quantitative relationships in chemical reactions.

Mole ratio

Ratio between substances from balanced equation coefficients.

Limiting reactant

Reactant consumed first that limits product formed.

Excess reactant

Reactant remaining after reaction ends.

Theoretical yield

Maximum possible amount of product.

Actual yield

Amount of product actually obtained.

Percent yield

Actual yield divided by theoretical yield times 100.

Thermochemistry

Study of heat transfer in chemical reactions.

System

Part of universe being studied.

Surroundings

Everything outside the system.

Heat

Transfer of thermal energy.

Temperature

Measure of average kinetic energy.

Endothermic process

Process that absorbs heat.

Exothermic process

Process that releases heat.

Specific heat capacity

Energy required to raise 1 g by 1°C.

Calorimetry

Measurement of heat transfer.

Enthalpy

Heat change at constant pressure.

Hess’s law

Overall enthalpy equals sum of reaction steps.

Electromagnetic radiation

Energy traveling as waves.

Wavelength

Distance between wave peaks.

Frequency

Number of waves passing a point each second.

Photon

Packet of electromagnetic energy.

Bohr model

Model with electrons in fixed energy levels.

Ground state

Lowest-energy arrangement of electrons.

Excited state

Higher-energy arrangement of electrons.

Orbital

Region where electrons are likely found.

Aufbau principle

Electrons fill lowest-energy orbitals first.

Pauli exclusion principle

An orbital holds at most two electrons with opposite spins.

Hund’s rule

Electrons occupy equal-energy orbitals singly first.

Atomic radius

Size of an atom.

Ionization energy

Energy required to remove an electron.

Electronegativity

Ability of atom to attract electrons.

Chemical bond

Force holding atoms together.