Comprehensive Physics and Chemistry Review

Comprehensive practice flashcards defining core terms, laws, principles, and concepts across physical chemistry, atomic structure, stoichiometry, thermochemistry, reaction kinetics, and Newtonian mechanics.

Atomic Number

The number of protons found in the nucleus of an atom, which uniquely determines the element's identity and corresponds to the smaller number on most periodic tables.

Mass Number

The total sum of protons and neutrons in the nucleus of an atom, which accounts for virtually all of the atom's mass.

Isotopes

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers due to differing numbers of neutrons, resulting in identical chemical reactivity but slightly different physical properties.

Valence Electrons

The electrons situated in the outermost energy level (valence shell) of an atom that participate in chemical bonding and determine an element's position on the periodic table.

Quantum Mechanical Model

An atomic model that determines the allowed energies an electron can have and predicts the probability of locating an electron within an electron cloud (estimating its position roughly $90\%$ of the time).

Atomic Orbital

A three-dimensional region of space within an electron subshell where there is a high probability of finding an electron, categorized into $s$, $p$, $d$, and $f$ sublevels.

s Orbital

A spherically symmetrical atomic orbital found in every principal energy level that has the lowest energy of the subshells and can hold a maximum of $2$ electrons.

p Orbital

A dumbbell-shaped atomic orbital that exists as a set of three mutually perpendicular orientations ($p_x$, $p_y$, $p_z$) capable of holding up to $6$ electrons in total.

Aufbau Principle

The rule governing electron configurations stating that electrons occupy the orbitals of lowest energy first (starting from $1s$) before occupying higher-energy sublevels.

Pauli Exclusion Principle

The quantum mechanical principle stating that an orbital can hold a maximum of two electrons, and those two electrons must have opposite spins (represented as clockwise and anticlockwise).

Hund's Rule

The rule stating that electrons occupy degenerate orbitals singly with parallel spins before any orbital is doubly occupied by a second electron with opposite spin.

Condensed Electron Configuration

A shorthand notation (noble gas notation) in which the symbol of the preceding noble gas represents the inner core shells, followed explicitly by the configuration of the valence electrons.

Alkali Metals

The elements in Group 1 of the periodic table, characterized by having $1$ valence electron, being soft and shiny, and reacting violently with water to form alkaline solutions.

Halogens

The highly reactive non-metallic elements in Group 17 that have $7$ valence electrons and readily gain $1$ electron to form salts with alkali metals.

Noble Gases

The unreactive, colorless, inert gases in Group 18 of the periodic table whose outermost electron shells are completely filled.

Metalloids

Elements positioned along the stair-step line of the periodic table that possess physical and chemical properties intermediate between those of metals and non-metals.

Dmitri Mendeleev

The Russian chemist who created the first accepted periodic table in 1869 by arranging elements according to atomic mass and leaving open spaces for predicted undiscovered elements.

Synthesis Reaction

A chemical reaction in which two or more simple reactants combine together to form a single, more complex product ($A + B \rightarrow AB$).

Decomposition Reaction

A chemical reaction in which a single compound breaks down into two or more simpler substances ($AB \rightarrow A + B$).

Single Displacement Reaction

A chemical reaction in which an uncombined element replaces another element from a compound ($A + BC \rightarrow AC + B$).

Double Displacement Reaction

A chemical reaction in which parts of two ionic compounds exchange ions to form two new compounds ($AB + CD \rightarrow AD + CB$).

Combustion Reaction

A rapid chemical reaction in which a hydrocarbon fuel reacts with oxygen gas ($O_2$) to produce carbon dioxide ($CO_2$), water ($H_2O$), and heat.

Oxidation

The process during a chemical reaction where an atom, ion, or molecule loses electrons (summarized by the mnemonic LEO: Lose Electrons Oxidation).

Reduction

The process during a chemical reaction where an atom, ion, or molecule gains electrons (summarized by the mnemonic GER: Gain Electrons Reduction).

Law of Conservation of Matter

The fundamental principle stating that matter cannot be created or destroyed in a closed system, requiring the total mass and atom counts of reactants to equal those of products.

Stoichiometric Coefficient

A whole number placed directly before a chemical formula in a reaction equation to balance the number of atoms on both sides without modifying chemical subscripts.

Precipitation Reaction

A specific class of double displacement reactions occurring in aqueous solution that results in the formation of an insoluble solid product called a precipitate.

Rate of Reaction

The change in the amount or concentration of a reactant or product per unit of time ($\text{Rate} = \frac{\Delta \text{amount}}{\Delta t}$), always expressed as a positive quantity.

Initial Rate

The instantaneous speed of a chemical reaction at the moment it begins ($t = 0$), measured from the slope of the tangent to the curve at the origin when reactant concentration is highest.

Instantaneous Rate

The reaction speed at a single specific instant in time, determined graphically by calculating the gradient of the tangent to the concentration-time curve at that specific point.

Average Rate

The overall rate of reaction measured across an extended time interval, computed by dividing the total concentration change by the total elapsed time.

Collision Theory

A model stating that for a chemical reaction to occur, reactant particles must collide with each other, possess sufficient activation energy, and collide in the correct geometric orientation.

Activation Energy

The minimum kinetic energy that colliding particles must possess to overcome repulsive forces and initiate a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed by providing an alternative reaction pathway with a lower activation energy.

Molecular Mass

The sum of the atomic masses of all atoms present in a molecular formula, measured in atomic mass units ($\text{amu}$).

Avogadro's Number

The fundamental constant equal to $6.02 \times 10^{23}$, defining the number of representative particles (atoms, molecules, or ions) present in one mole of a pure substance.

Molar Mass

The mass in grams of one mole of a substance, quantitatively identical to the formula weight in atomic mass units but expressed with units of $\text{g}\cdot\text{mol}^{-1}$.

Limiting Reactant

The reactant that is completely consumed first in a chemical reaction, thereby limiting the theoretical yield of product that can be formed.

Theoretical Yield

The maximum quantity of product that can be generated in a reaction, calculated from complete consumption of the limiting reactant under ideal stoichiometric conditions.

Percent Yield

The ratio of the experimentally measured actual yield to the calculated theoretical yield, expressed as a percentage: $\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$.

Empirical Formula

The simplest chemical formula of a compound showing the lowest whole-number ratio of atoms of each element present.

Thermochemistry

The study of energy transformations and heat transfers that take place during chemical reactions and physical phase transitions.

System and Surroundings

The conceptual division where the 'system' represents the chemical reaction itself, and the 'surroundings' represent everything outside the reaction container that exchanges energy with it.

Enthalpy Change (\Delta H)

The heat exchanged between a system and its surroundings at constant pressure, calculated as the difference between the enthalpies of products and reactants ($\Delta H = H_{\text{products}} - H_{\text{reactants}}$).

Exothermic Reaction

A chemical reaction that releases excess heat energy to its surroundings ($\Delta H < 0$), causing the temperature of the reaction mixture and environment to rise.

Endothermic Reaction

A chemical reaction that absorbs thermal energy from its surroundings ($\Delta H > 0$), causing the temperature of the reaction mixture to fall.

Newton's First Law of Motion

The principle of inertia stating that an object maintains its velocity (constant speed and straight-line direction) or remains at rest unless acted upon by a net unbalanced external force ($\Sigma \mathbf{F} = \mathbf{0}$).

Inertia

The inherent physical property of a mass that resists changes in its state of rest or constant-velocity motion.

Newton's Second Law of Motion

The physical law stating that the acceleration of a body is directly proportional to the net external force acting on it and inversely proportional to its mass ($\mathbf{F}_{\text{net}} = m\mathbf{a}$).

Newton's Third Law of Motion

The interaction law stating that when body A exerts a force on body B, body B simultaneously exerts an equal and opposite force on body A ($\mathbf{F}_{A\text{ on }B} = -\mathbf{F}_{B\text{ on }A}$), acting on two separate bodies.

Free Fall

The vertical motion of an airborne object when gravity is the sole force acting upon it, unaffected by air drag or buoyant forces.

Acceleration Due to Gravity (g)

The constant downward acceleration experienced by all objects in free fall near Earth's surface, possessing an exact magnitude of $9.8\,\text{m/s}^2$.

Linear Momentum

A vector quantity representing the product of an object's mass and its velocity ($\mathbf{p} = m\mathbf{v}$), measured in kilogram metres per second ($\text{kg}\cdot\text{m/s}$).

Impulse

The product of the net force acting on an object and the time interval of impact ($\mathbf{J} = \mathbf{F}\Delta t$), measured in Newton-seconds ($\text{N}\cdot\text{s}$).

Impulse-Momentum Theorem

The physical theorem derived from Newton's Second Law stating that the impulse delivered to an object is identically equal to its change in momentum ($\mathbf{F}\Delta t = \Delta \mathbf{p}$).

Gravitational Potential Energy (E_p)

The energy stored in an object due to its vertical position within a gravitational field, calculated as $E_p = mgh$, where $h$ is vertical displacement.

Kinetic Energy (E_k)

The energy an object possesses by virtue of its mass and speed, calculated using the relationship $E_k = \frac{1}{2}mv^2$.

Isolated System

A physical system of interacting bodies subject to zero net external force ($\Sigma \mathbf{F}_{\text{ext}} = \mathbf{0}$) and exchanging no matter with its surroundings.

Law of Conservation of Momentum

The law stating that within an isolated system, the total vector momentum before any interaction or collision is equal to the total vector momentum afterwards ($\Sigma \mathbf{p}_{\text{initial}} = \Sigma \mathbf{p}_{\text{final}}$).

Elastic Collision

A collision between bodies in which both total vector momentum and total kinetic energy ($E_k$) are fully conserved, with no energy lost to heat, sound, or permanent deformation.

Inelastic Collision

A collision in which total momentum is conserved, but total kinetic energy is not conserved because some energy transforms into thermal, sound, or deformation energy.