Summer Chem FINAL EXAM

Atom

The basic particles of the chemical elements. Consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms.

Element

More than one hundred substances that cannot be chemically broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms.

Compound

A chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds.

Law of Conservation of Matter

Matter cannot be created or destroyed, only changed

Valence Electrons

Electrons in the outermost shell of an atom

Atomic Number

Number of protons found in the nucleus of an atom of that element

Mass Number

Sum of the number of protons and neutrons present in the nucleus of an atom

Isotopes

Sum of the number of protons and neutrons present in the nucleus of an atom

Average Atomic Mass

The weighted average of the masses of all naturally occurring isotopes of an element

Radioactive Decay

the process by which an unstable atomic nucleus loses energy by emitting radiation

Fusion

A process where two or more atomic nuclei come together to form a heavier nucleus. This process releases a significant amount of energy. Fusion is the fundamental energy source of stars, including our Sun, where hydrogen nuclei fuse to form helium and release energy in the form of light and heat.

Fission

A nuclear reaction in which a heavy atomic nucleus splits into two or more smaller nuclei, along with a few neutrons and a significant amount of energy. This process is the principle behind nuclear power plants and atomic bombs.

Cations

Positively charged ions that are formed when an atom or molecule loses one or more electrons. This loss of electrons results in a net positive charge because the number of protons (positively charged particles) in the nucleus exceeds the number of electrons (negatively charged particles) surrounding the nucleus.

Anions

Negatively charged ions that are formed when an atom or molecule gains one or more electrons, resulting in a net negative charge because the number of electrons exceeds the number of protons in the nucleus.

Electronegativity

A measure of the ability of an atom in a bond to attract electrons

Aufbau Principle

Electrons fill the lowest energy orbital first

Pauli Exclusion Principle

No two electrons in the same atom can have the same set of quantum numbers

Chemical Bond

A force/mutual electrical attraction that holds atoms together in a substance

Molecule

Compound formed when 2 or more elements are covalently bonded

Ionic Bond

Formed when electrons are transferred from the cation to the anion

Polyatomic Ion

A positively or negatively charged, covalently bonded group of atoms

Transition Metal

Metals that “transition” because they can form many different ions

Metallic Bond

An interaction that holds metal atoms together through a shared pool of valence electrons

Covalent Bond

The bond between nonmetallic atoms that share electrons

Electron Domain

The space occupied by electrons

Lone Pairs

Electrons NOT in a bond

Bonding Pairs

Electrons shared in a bond

Polar Molecules

Covalent compounds with partial charges in different locations within the overall neutral molecule

Nonpolar Molecules

Covalent compounds with no partial charges because the electrons are equally shared

Intermolecular Forces

The attractive forces between particles in a substance

Chemical Equilibrium

A dynamic process where there is no net change occurring in the amount of reactants and products in the system, thus no visible change

Le Chatelier’s Principle

When conditions change for a system at equilibrium, the system responds by reducing the effect of the change

Mole

Unit of measurement for the amount of a substance

Molar Mass

The mass of one mole of pure substance (measured in g/mol)

Limiting Reactant

The reactant that limits the amount of product that can be made

Excess Reactant

The reactant that isn’t completely used up in the reaction

Actual Yield

The measured amount of product actually made from a reaction

Theoretical Yield

The maximum amount of product that could be made from a given amount of reactant

Percent Yield

The ratio of what could have been produced to what actually was produced

Kinetic Energy

Energy in motion

Temperature

Measure of the average kinetic energy of particles in an object

Pressure

Force per unit area on a surface

Solubility

A measure of how well one substance dissolves in another

Dissolution

The process of dissolving, where the solute separates and is surrounded by molecules of solvent

Dissociation

The separation of ions from an ionic compound as it dissolves

Molarity

(M) the concentration of solution expressed in number of moles of solute per liter of solution

Saturated Solution

A solution containing the max amount of dissolved solute at a given temperature

Supersaturated Solution

A solution containing more dissolved solute than a saturated solution in the same conditions; above its max capacity

Unsaturated Solution

A solution containing less dissolved solute than a saturated solution in the same conditions; below its max capacity

Salt

An ionic compound made from the cation of a base and an anion from an acid

Arrhenius Acid

A chemical compound that increases the concentration of hydrogen ions in an aqueous solution

Arrhenius Base

A substance that increases the concentration of hydroxide ions in an aqueous solution

Bronsted-Lowry Acid

A proton donor (in the form of a hydrogen ion)

Bronsted-Lowry Base

A proton acceptor (in the form of a hydrogen ion)

Amphoteric

A substance that can act as an acid or a base, depending on what else is in the solution with it

pH

A mathematical scale representing the concentration of H₃O⁺ ions on a scale of 0-14.

pOH

A mathematical scale representing the concentration of OH^- ions on a scale of 0-14.

Thermal Energy

The total amount of energy in particles in a sample

Activation Energy

The minimum amount of energy needed to get particles to collide with enough force to start a chemical reaction

Endothermic

A reaction with a net absorption of energy (+ΔH)

Exothermic

A reaction with a net release of energy (-ΔH)

Catalyst

A substance that speeds up the rate of the reaction by lowering the activation energy without being changed by it

Enthalpy

Refers to energy as heat content in a system

Entropy

A measure of the degree of randomness of particles in a system