Grade 11 Chemistry Vocabulary Flashcards

A comprehensive vocabulary list from Grade 11 Chemistry covering Atomic Structure, Bonding, States of Matter, Kinetics, Equilibrium, and Organic Chemistry.

Atomos

A term suggested by the Greek philosopher Democritus (460–370 BC) meaning "indivisible," referring to tiny, indestructible particles that make up matter.

Dalton’s Atomic Theory

An early atomic theory developed by John Dalton in 1808 based on the law of conservation of mass and the law of definite proportions.

Cathode Rays

Rays that originate from the negative electrode (cathode) in an evacuated glass tube; J.J. Thomson concluded they consist of a beam of negatively charged particles (electrons).

Radioactivity

The spontaneous emission of particles and/or radiation from the unstable nuclei of certain atoms such as uranium or radium.

Alpha ($\alpha$) Rays

Radioactive emissions consisting of positively charged particles identical to helium nuclei, which have a mass about four times that of a hydrogen atom and twice the charge magnitude of an electron.

Beta ($\beta$) Rays

Electrons coming from inside the nucleus that are deflected by a negatively charged plate during radioactive decay.

Gamma ($\gamma$) Rays

High-energy rays emitted by radioactive substances that have no charge and are not affected by external electric or magnetic fields.

Neutron

A nuclear particle discovered by James Chadwick leads in 1932 that has no electric charge and a mass ($1.67493 \times 10^{-27}\,kg$) almost identical to that of a proton.

Atomic Number (Z)

The number of protons in the nucleus of each atom of an element, which identifies the element.

Mass Number (A)

The total number of protons and neutrons in the nucleus of an atom.

Isotopes

Atoms of the same element that have the same atomic number but different numbers of neutrons and different mass numbers.

Electromagnetic Radiation (EMR)

The emission and transmission of energy in the form of electromagnetic waves, characterized by wavelength ($\lambda$), frequency ($\nu$), and speed ($c$).

Quantum

The smallest discrete quantity of energy that can be emitted or absorbed, as proposed by Max Planck.

Photoelectric Effect

A phenomenon in which electrons are ejected from the surface of certain metals exposed to light of at least a certain minimum threshold frequency ($\nu_0$).

Photons

Particles of light or energy packets that make up electromagnetic radiation.

Wave-Particle Duality

The concept proposed by de Broglie that matter and energy show both wave and particulate properties, especially significant at the atomic level.

Heisenberg Uncertainty Principle

A principle stating it is not possible to know with great certainty both an electron’s position and its momentum at the same time.

Orbital

A region in space around the atom's nucleus where there is a high probability (about 90%) of finding an electron.

Principal Quantum Number ($n$)

A quantum number that describes the main energy level or shell an electron occupies; it can be any positive integer ($1, 2, 3...$).

Angular Momentum Quantum Number ($\ell$)

Also called the azimuthal quantum number, it designates the shape of the atomic orbitals and takes values from $0$ to $n-1$.

Aufbau Principle

A scheme used to reproduce ground state electron configurations by filling orbitals in order of increasing energy ($1s$, then $2s$, $2p$, etc.).

Hund’s Principle

A rule stating that equal energy (degenerate) orbitals are each occupied by a single electron before a second electron with opposite spin enters the same orbital.

Pauli’s Exclusion Principle

A principle stating that no two electrons in an atom can have the same set of four quantum numbers.

Valence Electrons

The electrons in the outermost principal quantum level of an atom, which are involved in chemical bonding.

Ionic Bond

A bond formed by the electrostatic attraction between positive and negative ions resulting from the transfer of electrons.

Lattice Energy ($U$)

The enthalpy change that occurs when 1 mol of an ionic solid separates into gaseous ions; it indicates the strength of ionic interactions.

Covalent Bond

A bond formed when a pair of electrons is shared between two atoms, resulting in greater electron density between the nuclei.

Resonance

A condition in which two or more valid Lewis structures can be written for a molecule, and the actual structure is a composite (hybrid) of them.

Electronegativity

A measure of the extent to which an atom in a bond attracts the shared electron pair toward itself.

Dipole Moment ($\mu$)

A quantity defined as the product of the magnitude of the partial charge ($\delta$) and the distance ($d$) separating the charges in a polar molecule.

VSEPR Model

Valence Shell Electron Pair Repulsion model; a simple method for predicting molecular geometry based on minimizing repulsion between electron pairs.

Hydrogen Bond

A strong dipole-dipole attraction occurring between a partially positive hydrogen atom and a highly electronegative atom (N, O, or F) in another molecule.

London (Dispersion) Forces

Weak attractive forces resulting from instantaneous, temporary dipoles caused by varying electron positions around nuclei.

Metallic Bonding

The chemical bonding resulting from the attraction between metal cations and a surrounding "sea" of delocalized valence electrons.

Hybridization

An imaginary mixing process in which atomic orbitals rearrange to form new, equivalent hybrid orbitals ($sp$, $sp^2$, $sp^3$, etc.).

Sigma ($\sigma$) Bond

A localized covalent bond in which the highest electron density lies along the axis connecting the two nuclei.

Pi ($\pi$) Bond

A covalent bond formed by the sideways overlap of parallel $p$ orbitals, with electron density located above and below the sigma bond axis.

Plasma

The fourth state of matter; an ionized gas existing at extremely high temperatures, composed of positive ions and electrons.

Ideal Gas

A hypothetical gas whose pressure, volume, and temperature behavior is completely explained by the ideal gas equation ($PV = nRT$).

Diffusion

The process by which gas molecules spread rapidly and randomly through a container or another medium.

Vapor Pressure

The partial pressure of a vapor in dynamic equilibrium with its liquid in a closed container at a given temperature.

Chemical Kinetics

The area of chemistry concerned with the rates (speeds) of chemical reactions.

Activation Energy ($E_a$)

The minimum amount of energy required for a collision between reactant molecules to result in a chemical reaction.

Catalyst

A substance that increases the rate of reaction by providing an alternative reaction mechanism with a lower activation energy ($E_a$).

Dynamic Equilibrium

A state in a reversible reaction where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.

Le Châtelier’s Principle

A principle stating that if a change is imposed on a system at equilibrium, the position of the equilibrium will shift to reduce that change.

Reaction Quotient ($Q_c$)

A ratio of product concentrations to reactant concentrations used to determine the direction in which a reaction will proceed to reach equilibrium.

Haber Process

The industrial synthesis of ammonia ($NH_3$) from nitrogen ($N_2$) and hydrogen ($H_2$) using high pressure, heat, and an iron catalyst.

Contact Process

The industrial process for manufacturing sulfuric acid ($H_2SO_4$) involving the catalytic oxidation of sulfur dioxide ($SO_2$) to sulfur trioxide ($SO_3$).

Alcohols

Derivatives of hydrocarbons in which one or more hydrogen atoms have been replaced by a hydroxyl group ($-OH$).

Ethers

Organic compounds in which an oxygen atom is bonded to two alkyl or aryl substituents ($R-O-R'$).

Carbonyl Group

A functional group consisting of a carbon atom double-bonded to an oxygen atom ($C=O$).

Saponification

The process of base-catalyzed hydrolysis of an ester, commonly used to make soap.

Triglycerides

Triesters of glycerol and fatty acids; commonly known as fats (solids) or oils (liquids) depending on their physical state at room temperature.

Rancidity

The deterioration of fats and oils resulting in an unpleasant odor and flavor, caused by hydrolysis of ester linkages and oxidation of double bonds.