Chemistry Regents Exam Review

These flashcards cover important concepts from the Chemistry Regents Exam, including atomic structure, chemical bonding, reactions, the periodic table, and more.

The Atom

A fundamental unit of matter, consisting of a nucleus surrounded by electrons.

Dalton’s Model

Proposed that elements are made of atoms and that atoms of the same element are identical.

Rutherford Experiment

An experiment that demonstrated that atoms are mostly empty space with a dense, positively charged nucleus.

Bohr Model

Depicts electrons in fixed orbits around the nucleus, which is positively charged.

Wave-Mechanical Model

Modern atomic theory describing electrons in probabilistic 'clouds' or orbitals around the nucleus.

Proton

A positively charged particle found in the nucleus of an atom.

Neutron

A particle with no charge found in the nucleus of an atom.

Electron

A negatively charged particle that orbits the nucleus of an atom.

Atomic Mass Unit (amu)

A unit used to measure the mass of atomic and subatomic particles, defined as 1/12 the mass of a carbon atom.

Ground State

The lowest energy state of an atom, where electrons occupy the lowest available energy levels.

Excited State

A state of an atom where one or more electrons have absorbed energy and moved to higher energy orbitals.

Valence Electrons

The outermost electrons in an atom that determine its chemical properties.

Stable Atom

An atom with filled valence shells, which is less likely to react chemically.

Isotope

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

Half-Life

The time required for half of a sample of a radioactive substance to decay.

Transmutation

The process of converting one element into another through nuclear reactions.

Chemical Bond

The force that holds atoms together in a chemical compound.

Ionic Bonding

A type of bonding that occurs when electrons are transferred from one atom to another.

Covalent Bonding

A bond formed when two atoms share electrons.

Metallic Bonding

Bonding that occurs when electrons are free to move within a lattice of metal atoms.

Electronegativity

The ability of an atom in a molecule to attract shared electrons to itself.

Polar Molecule

A molecule with a partial positive charge on one side and a partial negative charge on the other.

Nonpolar Molecule

A molecule with an even distribution of charge, resulting in no distinct poles.

Mixture

A combination of two or more substances that retain their individual properties.

Pure Substance

A material composed of only one type of particle, with a uniform composition.

Homogeneous Mixture

A mixture that is uniform in composition throughout.

Heterogeneous Mixture

A mixture that is not uniform in composition and varies from one region to another.

Endothermic Reaction

A reaction that absorbs heat from its surroundings.

Exothermic Reaction

A reaction that releases heat to its surroundings.

Phase Change

The transition of a substance from one state of matter (solid, liquid, gas) to another.

Heat of Fusion

The energy required to convert one gram of a substance from solid to liquid.

Heat of Vaporization

The energy needed to convert one gram of a substance from liquid to gas.

Specific Heat Capacity

The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.

Kinetic Molecular Theory (KMT)

A theory that explains the behavior of gases based on the movement of particles.

Concentration

The amount of solute present in a given volume of solvent.

Collision Theory

The theory that chemical reactions occur when particles collide with sufficient energy and proper orientation.

LeChatelier’s Principle

The principle stating that if an external change is applied to a system at equilibrium, the system will adjust to minimize that change.

Acid

A substance that increases the concentration of hydrogen ions in solution.

Base

A substance that increases the concentration of hydroxide ions in solution.

Titration

A laboratory method used to determine the concentration of a solution by reacting it with a solution of known concentration.

Oxidation

A process in which electrons are lost from an atom.

Reduction

A process in which electrons are gained by an atom.

Organic Chemistry

The branch of chemistry that studies the structure, properties, and reactions of organic compounds and materials.

Hydrocarbon

A compound consisting entirely of hydrogen and carbon.

Functional Group

A specific group of atoms within a molecule that is responsible for characteristic chemical reactions.

Electrolyte

A substance that produces an electrically conducting solution when dissolved in water.

Nuclear Fission

The process of splitting a nucleus into two or more smaller nuclei.

Nuclear Fusion

The process where two light atomic nuclei combine to form a heavier nucleus.

Noble Gasses

Group 18 elements that have filled valence levels and are generally unreactive.

Hydrogen Bond

A weak bond formed between a hydrogen atom and an electronegative atom.

Spectroscope

An instrument used to study the properties of light and can be used to identify elements.

Chemical Reaction

A process that leads to the transformation of one set of chemical substances to another.

Empirical Formula

The simplest whole number ratio of elements in a compound.

Molecular Formula

Shows the actual number of atoms of each element in a molecule.

Structural Formula

Shows the arrangement of atoms within a molecule.

Balanced Chemical Equation

An equation that has the same number of each type of atom on both sides.

Molar Mass

The mass of one mole of a substance expressed in grams.

Heat of Reaction

The change in enthalpy during a chemical reaction.

Entropy

A measure of disorder or randomness in a system.

Saturated Hydrocarbon

A hydrocarbon that contains only single bonds between carbon atoms.

Unsaturated Hydrocarbon

A hydrocarbon that contains one or more double or triple bonds.

Isomer

Compounds that have the same molecular formula but different structural arrangements.

Gas Laws

Laws that describe the behavior of gases, including relationships between pressure, volume, and temperature.

pH scale

A scale used to specify the acidity or basicity of an aqueous solution, ranging from 0 (acidic) to 14 (basic).

Neutralization Reaction

A chemical reaction in which an acid and a base react to form salt and water.

Coefficient in Chemical Equations

Numbers that precede compounds to indicate the number of moles of each substance involved in a reaction.

Graham's Law of Effusion

States that the rate of effusion of a gas is inversely proportional to the square root of its molar mass.

Gravitational Potential Energy

The energy an object possesses due to its position in a gravitational field.

Chemical Equilibrium

A state in a chemical reaction where the rates of the forward and reverse reactions are equal.

Total Energy

The sum of kinetic energy and potential energy in a system.

Enthalpy

A measure of the total heat content of a system.

Calorimetry

The measurement of heat changes in chemical reactions.

Atomic Number

The number of protons in the nucleus of an atom, which determines the element's identity.

Metal

An element characterized by high electrical conductivity, ductility, and malleability.

Non-Metal

Elements that are typically poor conductors of heat and electricity.

Metalloid

An element with properties intermediate between metals and non-metals.

Chemical Change

A change that results in the formation of new chemical substances.

Physical Change

A change that affects one or more physical properties of a substance without altering its chemical composition.