Atoms, Elements, Spectrums, and Electron Configurations

Flashcards covering key terms, atomic models, wave properties, light theories, and electron configurations from the lecture.

Democritus's Atomic Theory

An early idea stating that all matter is composed of small, indivisible particles.

Dalton's Atomic Model

Model proposing that there is one specific type of atom for each element and that atoms combine to form compounds.

Thomson's Model

Also known as the Plum-Pudding model; discovered electrons and described the atom as negative electrons floating in positive material.

Rutherford's Model

Model that established the presence of a dense, positively charged nucleus at the center of the atom, with electrons orbiting in mostly empty space.

Speed of Light ($c$)

The constant speed at which all electromagnetic waves move through space, equal to $3.00 \times 10^8,m/s$.

Origin

The base line level of energy in a wave.

Crest

The highest point on a wave.

Trough

The lowest point on a wave.

Amplitude

The vertical distance measured from the wave's origin to its crest.

Wavelength

The distance from crest to crest or peak to peak on a wave.

Frequency ($\nu$)

The number of wave cycles that pass a specified point per second, measured in hertz ($Hz$) or cycles per second.

Photoelectric Effect

The ejection of electrons from a metal surface when illuminated by light above a specific minimum frequency.

Quantum

The minimum discrete quantity of energy that can be gained or lost by an electron.

Photon

A particle of electromagnetic radiation with zero mass that carries a quantum of energy.

Ground State

The lowest possible energy state of an atom.

Excited State

A state in which an atom possesses a higher potential energy level than its ground state.

Emission Spectrum

The spectrum of light emitted when excited electrons in an element drop back down to lower energy levels.

Heisenberg Uncertainty Principle

Principle stating that it is impossible to know both the precise position and velocity of an electron simultaneously.

Quantum Mechanical Model

Atomic model derived from Schrödinger's wave equation that treats electrons as waves and calculates the probability of electron location.

Electron Cloud

A 3D region surrounding the nucleus where there is a $90\%$ or higher probability of finding an electron.

Principal Quantum Number ($n$)

Integer value ($n = 1, 2, 3, \\dots$) designating the main energy level or shell of an electron.

Maximum Electron Capacity Formula

Formula given by $2n^2$ that calculates the maximum number of electrons an energy level $n$ can hold.

Energy Sublevel

Subdivisions (s, p, d, f) within a principal energy level, ordered by increasing energy $s < p < d < f$.

Orbital

A region within a sublevel that can hold a maximum of two electrons with opposite spins.

s Orbitals

Spherical-shaped orbitals present in every energy level, holding a maximum of 2 electrons in 1 orbital.

p Orbitals

Dumbbell-shaped orbitals starting at energy level 2, consisting of 3 orbitals holding up to 6 electrons.

d Orbitals

Orbitals starting at energy level 3, consisting of 5 orbitals holding up to 10 electrons total.

f Orbitals

Orbitals starting at energy level 4, consisting of 7 distinct shapes holding up to 14 electrons total.

Degenerate Orbitals

Orbitals belonging to the same sublevel that possess equal energy.

Aufbau Principle

Rule stating that electrons occupy the lowest available energy orbitals first.

Pauli Exclusion Principle

Rule stating that an orbital can hold a maximum of two electrons, and they must have opposite spins.

Hund's Rule

Rule stating that single electrons with parallel spins must occupy each equal-energy orbital before pairing up.

Valence Electrons

Electrons located in the outermost energy level of an atom.

Electron Dot Diagram

A visual representation where the chemical symbol represents the atomic nucleus and inner electrons, surrounded by dots for valence electrons.