Unit 1: Atomic Structure and Properties Flashcards

Vocabulary flashcards covering key concepts, formulas, and terminology from AP Chemistry Unit 1: Atomic Structure and Properties.

Avogadro's number

The constant $6.022 \times 10^{23}\,\text{mol}^{-1}$ that provides the quantitative connection between the number of moles in a pure sample of a substance and its actual number of constituent particles or formula units.

Mole

A unit containing approximately $6.022 \times 10^{23}$ particles, used by chemists to connect the laboratory mass of a substance to its actual number of microscopic particles.

Isotopes

Atoms of the same element that have different atomic masses because they contain different numbers of neutrons in their nucleus.

Mass Spectrum

A plot generated by mass spectrometry showing the mass or mass-to-charge ratio of an element's isotopes on the x-axis and their relative abundance or percent abundance on the y-axis.

Beer-Lambert Law

The chemical relationship defined by $A = \epsilon b c$, which directly relates the light absorbance ($A$) of a solution to its molar absorptivity ($\epsilon$), light path length ($b$), and solution concentration ($c$).

Empirical Formula

The chemical formula that represents the lowest whole-number ratio of atoms of each element in a compound.

Molecular Formula

A chemical formula that specifies the actual number of atoms of each element present in a molecule of a compound.

Law of Definite Proportions

The principle stating that the mass ratio of constituent elements in any pure sample of a given chemical compound is always constant.

Calibration Curve

A graph constructed using known concentration standards that allows the concentration of an unknown solution to be determined from a measurable physical property like absorbance.

Core Electrons

Electrons located in the inner energy shells of an atom, positioned closer to the positively charged nucleus than the outermost electrons.

Valence Electrons

Electrons occupying the outermost energy shell of an atom that govern chemical bonding, reactivity, and typical ionic charges.

Coulomb's Law

The fundamental force law represented by $F = \frac{q_1 q_2}{r^2}$, stating that the force between charged particles is proportional to their charges and inversely proportional to the square of the distance between them.

Aufbau Principle

The quantum mechanics principle stating that electrons sequentially fill the lowest available energy sublevels before filling higher ones.

Ionization Energy

The relative quantity of energy required to remove an electron from a specific subshell of a gaseous atom or ion.

Photoelectron Spectroscopy (PES)

An experimental technique measuring the binding energies of electrons in atoms, producing peaks where position indicates removal energy and peak height is proportional to the relative number of electrons in that subshell.

Effective Nuclear Charge

The net positive electrostatic attraction experienced by a specific electron in an atom, equal to the nuclear positive charge adjusted for core electron shielding.

Atomic Radius

The measure of atomic size, which increases down a group on the periodic table due to additional electron shells and decreases across a period due to increasing nuclear charge.

Electronegativity

The ability of a bonded atom within a molecule to attract shared valence electrons toward itself.