AP Chemistry Foundation Flashcard Deck

Comprehensive vocabulary flashcards covering basic chemical foundations, atomic structure, the mole, electron configuration, and introductory Photoelectron Spectroscopy (PES) as outlined in the AP Chemistry Foundations lecture notes.

Pure Substance

Matter with a constant composition and distinct chemical properties that cannot be separated by physical means. (Memory Hint: Pure = Same throughout.)

Element

A pure substance composed of only one type of atom that cannot be broken down chemically. (Memory Hint: Elemental = Single type.)

Compound

A pure substance composed of two or more different elements chemically bonded in a fixed ratio. (Memory Hint: Compound = Combined elements.)

Mixture

A physical combination of two or more substances that retain their individual identities and can be separated physically. (Memory Hint: Mixture = Merely mixed, not bonded.)

Atom

The basic unit of a chemical element, consisting of a dense nucleus surrounded by an electron cloud. (Memory Hint: Atom = Indivisible building block.)

Nucleus

The dense, positively charged center of an atom containing protons and neutrons. (Memory Hint: Nucleus = Core mass (+).)

Proton

A subatomic particle located in the nucleus with a positive charge ($+1$) and a mass of approximately $1\,amu$. (Memory Hint: P = Positive Proton.)

Neutron

A subatomic particle located in the nucleus with a neutral charge ($0$) and a mass of approximately $1\,amu$. (Memory Hint: N = Neutral Neutron.)

Electron

A subatomic particle orbiting the nucleus with a negative charge ($-1$) and negligible mass. (Memory Hint: E = External / Negative.)

Atomic Number (Z)

The number of protons in the nucleus of an atom, which uniquely identifies the element. (Memory Hint: Atomic Number = Proton ID.)

Mass Number (A)

The total number of protons and neutrons in an atom's nucleus. (Memory Hint: Mass = Protons + Neutrons.)

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons (different mass numbers). (Memory Hint: Iso-topes = Same proton top, different mass drop.)

Average Atomic Mass

The weighted average mass of all naturally occurring isotopes of an element, based on their relative abundances. (Memory Hint: Weighted average on Periodic Table.)

Relative Abundance

The percentage or fraction of a specific isotope found naturally on Earth for a given element. (Memory Hint: Abundance = How common it is.)

Coulomb's Law

A fundamental law stating that the force between charges is proportional to the product of their magnitudes and inversely proportional to the square of the distance between them ($F \propto \frac{q_1 q_2}{r^2}$). (Memory Hint: More charge = tight hold; more distance = weak fold.)

Mole (mol)

The SI unit for amount of substance, representing exactly $6.022 \times 10^{23}$ elementary entities. (Memory Hint: The chemist's dozen.)

Avogadro’s Number

The number of particles in exactly one mole of a substance, equal to $6.022 \times 10^{23}\,particles/mol$. (Memory Hint: $6.022 \times 10^{23} = 1\,mole$.)

Molar Mass

The mass in grams of one mole of a chemical substance, numerically equal to its atomic or formula mass in amu. (Memory Hint: Grams per mole ($g/mol$) from periodic table.)

Grams to Moles

Conversion achieved by dividing the given mass of a substance by its molar mass ($mol = \frac{g}{MM}$). (Memory Hint: Grams / Molar Mass = Moles.)

Moles to Grams

Conversion achieved by multiplying the given moles of a substance by its molar mass ($g = mol \times MM$). (Memory Hint: Moles \times Molar Mass = Grams.)

Particles to Moles

Conversion achieved by dividing the number of particles by Avogadro's number ($mol = \frac{particles}{N_A}$). (Memory Hint: Particles / $6.022 \times 10^{23} = Moles$.)

Moles to Particles

Conversion achieved by multiplying the moles of a substance by Avogadro's number ($particles = mol \times N_A$). (Memory Hint: Moles \times $6.022 \times 10^{23} = Particles$.)

Percent Composition

The percent by mass of each element in a compound, calculated as ($\text{mass of element} / \text{total molar mass}$) \times $100\%$. (Memory Hint: Part over whole times 100.)

Empirical Formula

The simplest chemical formula showing the lowest whole-number ratio of atoms of each element in a compound. (Memory Hint: Empirical = Most reduced ratio.)

Molecular Formula

The actual chemical formula showing the exact number of atoms of each element in a molecule of a compound. (Memory Hint: Molecular = Real deal formula.)

Ground State

The lowest energy, most stable configuration of electrons in an atom. (Memory Hint: Ground = Lowest floor.)

Excited State

A high-energy state achieved when an electron absorbs energy and jumps to a higher energy level. (Memory Hint: Excited = Jumped up a floor.)

Photon

A quantum of electromagnetic radiation released or absorbed when an electron transitions between energy levels. (Memory Hint: Photon = Light packet.)

Energy Level (Shell)

The quantized region around a nucleus designated by the principal quantum number ($n$) where electrons reside. (Memory Hint: Shell = Distance from core ($n=1,2,3$).)

Valence Electron

An electron in the outermost energy level of an atom that participates in chemical bonding. (Memory Hint: Valence = Outer rim bonding.)

Core Electron

An electron in an inner energy level that does not participate in chemical bonding and shields valence electrons. (Memory Hint: Core = Inner shield.)

Orbital

A three-dimensional region of space around the nucleus where there is a high probability ($90\%$) of finding an electron. (Memory Hint: Orbital = Electron house (max $2\,e^-$).)

Electron Configuration

A notation that describes the distribution of electrons among the various orbitals and subshells of an atom. (Memory Hint: Electron address/map (e.g., $1s^2 2s^2$).)

Aufbau Principle

The rule stating that electrons fill the lowest available energy orbitals first before moving to higher ones. (Memory Hint: Aufbau = Build up from bottom.)

Hund’s Rule

The rule stating that electrons occupy degenerate orbitals singly and with parallel spins before pairing up. (Memory Hint: Bus seat rule: sit alone before pairing.)

Pauli Exclusion Principle

The rule stating that no two electrons in an atom can have the exact same four quantum numbers; an orbital holds max $2$ electrons with opposite spins. (Memory Hint: Pauli = Two per room, opposite spins.)

s-block

The region of the periodic table (Groups 1, 2, and He) where valence electrons fill s-orbitals (spherical, max $2$ electrons). (Memory Hint: s = Sphere (Groups 1-2).)

p-block

The region of the periodic table (Groups 13-18) where valence electrons fill p-orbitals (dumbbell-shaped, max $6$ electrons). (Memory Hint: p = Peanut/Dumbbell (Groups 13-18).)

d-block

The region of the periodic table (Transition Metals) where electrons fill d-orbitals (clover-shaped, max $10$ electrons). (Memory Hint: d = Double clover (Transition Metals).)

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge. (Memory Hint: Ion = Charged particle.)

Cation

A positively charged ion formed when an atom loses one or more valence electrons. (Memory Hint: Ca+ion = Positive (t looks like +).)

Anion

A negatively charged ion formed when an atom gains one or more valence electrons. (Memory Hint: A-N-Ion = A Negative Ion.)

Photoelectron Spectroscopy (PES)

An experimental technique that measures the binding energy of electrons in a sample by bombarding it with high-energy photons. (Memory Hint: PES = Photons in, electrons out; proves electron shells.)

Binding Energy

The energy required to remove an electron from an atom; high binding energy corresponds to electrons closer to the nucleus. (Memory Hint: Binding = Hold strength (PES peak position).)