Chemistry Regents Exam Review - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the provided lecture notes for the Chemistry Regents exam review.

Dalton's Model

Elements are composed of identical atoms; compounds form from combinations of atoms.

Rutherford experiment

Atoms are mostly empty space with a small, dense, positively charged nucleus.

Bohr Model

Nucleus with electrons in circular orbits and fixed energy levels.

Wave-Mechanical Model

Electrons occupy an electron cloud (orbitals) around a dense nucleus; energy levels exist.

Valence electrons

Outermost electrons that determine chemical properties; typically up to 8 (2 for H/He).

Isotope

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

Half-life

The constant time for exactly half of a radioactive sample to decay.

Transmutation

Change in the nucleus turning one element into another; natural or artificial.

Fission

Splitting of a heavy nucleus into lighter nuclei, releasing energy.

Fusion

Light nuclei combine to form heavier nuclei, releasing energy (sun’s power).

Ionic bond

Bond formed by transfer of electrons; high melting points; forms crystals; conducts when dissolved or molten.

Covalent bond

Bond formed by sharing electrons between nonmetals; molecules; lower melting/boiling points.

Polar covalent

Covalent bond with unequal sharing due to electronegativity difference.

Hydrogen bond

Strong intermolecular force between H and O/F/N; raises boiling/melting points.

Lewis structures

Electron-dot diagrams showing valence electrons and bonding; aims for octet.

Pure substance

Substance with fixed composition and uniform properties (elements or compounds).

Mixture

Two or more substances physically combined; homogeneous or heterogeneous.

Physical change

Change in form or state without changing identity; e.g., freezing, boiling.

Heat of fusion

Energy to convert 1 g of solid to liquid at melting point.

Specific heat

Energy to raise 1 g of substance by 1°C; water = about 4.18 J/g·K.

Kinetic energy

Energy of motion; KE = 1/2 mv^2.

Potential energy

Stored energy due to position.

Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed.

Exothermic

Reactions that release heat to the surroundings.

Atomic number

Number of protons in an atom; identifies the element.

Atomic mass

Sum of protons and neutrons in the nucleus; electrons contribute negligibly.

Alkali metals

Group 1 metals; highly reactive; form compounds.

Halogens

Group 17 elements; highly reactive nonmetals; form salts with alkali metals.

Noble gases

Group 18; filled valence shells; generally inert.

Periods

Rows on the periodic table; indicate energy level count.

Groups

Columns on the periodic table; share valence configuration and similar properties.

Empirical formula

Simplest whole-number ratio of elements in a compound.

Molecular formula

Actual number of atoms of each element in a molecule.

Balanced equation

Equation with equal numbers of atoms on both sides; mass is conserved.

Mole ratio

Proportions from coefficients to relate amounts of reactants/products.

Solution

Homogeneous mixture of solute dissolved in solvent.

Solvent

Substance that dissolves the solute.

Solubility

Ability of a solute to dissolve; depends on temperature and nature.

Like dissolves like

Polar dissolves polar; nonpolar dissolves nonpolar.

Boiling point elevation

Solute raises the boiling point of the solvent.

Collision theory

Reactions occur when particles collide with proper energy and orientation.

Equilibrium

Forward and reverse reactions occur at equal rates; concentrations constant.

Le Chatelier’s principle

System at equilibrium shifts to counteract a stress (pressure, concentration, temp, etc.).

Activation energy

Minimum energy required for a reaction to proceed.

Catalyst

Substance that provides an alternative path with lower activation energy.

Arrhenius theory

Acids yield H+ in solution; bases yield OH-; electrolytes.

pH

Measure of how acidic or basic a solution is; 0-14 scale; 7 neutral.

Neutralization

Acid reacts with base to form salt and water; net ionic: H+ + OH- → H2O.

Hydronium

H3O+; another way to represent H+ in solution.

Oxidation

Loss of electrons; increase in oxidation number.

Reduction

Gain of electrons; decrease in oxidation number.

Oxidation number

Formal charge used to track electron transfer in a reaction.

Electrochemical cell

Device that converts chemical energy to electrical energy (voltaic) or uses electricity to drive chemical change (electrolytic).

Hydrocarbon

Compound consisting of carbon and hydrogen only.

Saturated hydrocarbon

Hydrocarbon with only single C–C bonds.

Unsaturated hydrocarbon

Contains at least one C=C or C≡C bond.

Functional group

Specific group of atoms defining properties and reactivity of organic molecules.

Isomer

Compounds with same molecular formula but different structures.

Scientific method

Systematic process for investigating natural phenomena.

Graph

A visual data representation used to show trends and relationships.

Significant figures

Rules for precision in measurements to reflect uncertainty.

Lab safety

Practices to prevent accidents and injuries in the laboratory.