P.S./Chemistry Regents Practice - Vocabulary Flashcards

Vocabulary flashcards covering key terms and concepts from the lecture notes.

Atom

The basic unit of matter consisting of a nucleus and electrons; mostly empty space.

Nucleus

Center of the atom containing protons and neutrons.

Electron

Negatively charged subatomic particle that orbits the nucleus in electron shells.

Shell model

Arrangement of electrons in discrete energy levels or shells outside the nucleus.

Isotope

Atoms of the same element with different numbers of neutrons (different mass numbers).

Atomic mass

Weighted average mass of an element’s naturally occurring isotopes.

Atomic number

Number of protons in the nucleus; defines the element.

Ion

Atom or molecule with a net electric charge due to loss or gain of electrons.

Ionization energy

Energy required to remove an electron from an atom.

Electronegativity

A measure of an atom’s ability to attract electrons in a bond.

Periodic table

Organizes elements by increasing atomic number and recurring properties.

Metalloid

Element with properties between a metal and a nonmetal (e.g., Te).

Compound

Substance formed by chemically combining two or more elements in a fixed ratio.

Element

A substance consisting of one type of atom; cannot be broken down by chemical means.

Mixture

A physical combination of two or more substances that can be separated.

Homogeneous mixture

Uniform composition throughout (a solution is a type of this).

Heterogeneous mixture

Non-uniform composition with distinct phases.

Mole

Amount of substance containing Avogadro’s number of particles (6.022×10^23).

Molarity

Moles of solute per liter of solution.

Balanced equation

Chemical equation with equal numbers of atoms of each element on both sides.

Activation energy

Minimum energy required for a reaction to occur.

Catalyst

Substance that speeds up a reaction by lowering the activation energy.

Exothermic

Process that releases heat to the surroundings.

Endothermic

Process that absorbs heat from the surroundings.

Heat of reaction

The energy change that accompanies a chemical reaction.

Kinetic molecular theory

Model describing gas particles as tiny, fast-moving particles with elastic collisions and negligible volume.

Ideal gas

A hypothetical gas that perfectly follows the kinetic molecular theory.

STP

Standard temperature and pressure (0°C and 1 atm) used for gas calculations.

Polarity

Unequal distribution of electric charge in a molecule.

Electronegativity difference

Difference in electronegativity between bonded atoms; larger differences lead to polar/ionic bonds.

Polar molecule

Molecule with a net dipole moment due to uneven charge distribution.

Ionic bond

Bond formed by electron transfer creating oppositely charged ions with electrostatic attraction.

Covalent bond

Bond formed by sharing electron pairs between atoms.

Metallic bond

Bond in metals arising from a “sea” of delocalized electrons.

Hydrogen bond

Strong dipole-dipole interaction involving hydrogen bonded to N, O, or F.

Double bond

A bond formed by sharing four electrons between two atoms (as in C=C).

Unsaturated hydrocarbon

Hydrocarbon containing one or more double or triple bonds.

Alkane

Saturated hydrocarbon with only single bonds (no double/triple bonds).

Alkene

Unsaturated hydrocarbon with at least one C=C double bond.

Alkyne

Unsaturated hydrocarbon with at least one C≡C triple bond.

Saturated hydrocarbon

Hydrocarbon with only single bonds between carbon atoms.

Solubility

Ability of a substance to dissolve in a solvent at a given temperature.

Salt

Ionic compound formed from a neutralization reaction between an acid and a base.

Neutralization

Acid-base reaction producing water and a salt.

pH

A measure of how acidic or basic a solution is, from 0 to 14.

Hydronium ion

H3O+, the acidic species in aqueous solution.

Hydroxide ion

OH−, the basic species in aqueous solution.

Acid

Substance that donates a proton (H+) in aqueous solution.

Base

Substance that accepts a proton (H+) or donates OH−.

Lewis dot diagram

Diagram showing valence electrons as dots around the symbol of an element.

Valence electrons

Electrons in the outermost energy level involved in bonding.

Electron configuration

Arrangement of electrons in an atom’s energy levels and subshells.

Noble gas configuration

Stable electron arrangement achieved by complete outer shells (octet or filled shells).

Mass number

Total number of protons and neutrons in the nucleus (A).

Atomic mass unit

amu; unit for expressing atomic and molecular masses.

Mass number vs atomic number

Mass number (A) = protons+neutrons; atomic number (Z) = protons.

Nuclear fission

Splitting of a heavy nucleus into lighter nuclei with energy release.

Nuclear fusion

Joining of light nuclei to form a heavier nucleus with energy release.

Alpha particle

Helium-4 nucleus emitted in some radioactive decay processes.

Beta particle

High-energy electron (or positron) emitted in radioactive decay.

Half-life

Time required for half of a radioactive sample to decay.

Isotopes

Atoms of the same element with different numbers of neutrons; same Z, different A.

Periodic trends

Systematic changes in properties (e.g., radius, ionization) across periods/groups.

Solubility rules

Guidelines used to predict whether a compound will dissolve in water.

Collision theory

Reaction rate depends on effective collisions with correct energy and orientation.

Equilibrium

State where forward and reverse reaction rates are equal and concentrations are constant.

Lewis structure

A diagram showing the bonding electrons around atoms in a molecule.