AP Chem Unit 1

Compound

A theory stating that a compound consists of atoms of two or more elements.

Fundamental Charge of Electron

1.6 x 10^-19 C is the fundamental charge of an electron.

Unified Atomic Mass (u)

1/12 the mass of a single carbon-12 isotope, also referred to as Dalton (Da) or Atomic Mass Unit (amu).

Isotopes

Atoms of the same element with different numbers of neutrons, separated based on their mass-to-charge ratio in mass spectroscopy.

Mass Spectroscopy

An analytical tool useful for measuring the mass-to-charge ratio (m/z) of the molecules in a sample.

Molecular Formula

A chemical formula representing the actual number of atoms in a molecule, always a whole number multiple of the empirical formula.

Mole

The amount of substance where there are 6.022 x 10^23 discrete atoms or molecules.

Ionization Energy

The minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule.

Cations and Anions

Cations are positively charged ions formed by losing electrons; anions are negatively charged ions formed by gaining electrons.

Effective Nuclear Charge (Zeff)

The pulling force that a valence electron actually feels, calculated as the number of protons minus the number of core electrons.

Hund's Rule of Maximum Multiplicity

Every orbital in a sublevel is singly occupied before any orbital is doubly occupied, all single electrons having the same spin.

Pauli’s Exclusion Principle

No two electrons can have the same set of quantum numbers and cannot be in the same energy state.

Binding Energy

The least energy required to remove a particle from a system of particles, indicative of how tightly an electron is held in an atom.

Ground State

The lowest energy state of an electron in an atom.

Excited State

A state in which an electron has absorbed energy and jumped to a higher energy level.

Coloumb's Law

F = (q1 * q2)/r², describes the electrostatic force between charged particles.

Ion Source (Mass Spectrometer)

The part of a mass spectrometer where a small sample is ionized.

Mass Analyzer

The component of a mass spectrometer that separates ions based on their mass-to-charge ratio.

Detector (Mass Spectrometer)

Measures and displays the counts of the separated ions in a mass spectrometer.

Electronegativity

The ability of an atom to attract electrons in a bond, which increases across a period and decreases down a group.

Atomic Radius

The distance from the nucleus to the valence shell of an atom, decreases as atomic number increases.

Limiting Reactant

The reactant that is present in the smallest stoichiometric amount and limits the extent of the reaction.

Photoelectron Spectroscopy (PES)

An experimental technique measuring the relative energy of electrons in atoms or molecules, utilizing photoionization.