Electrons in Atoms and the Periodic Table

A collection of vocabulary flashcards summarizing key concepts from the lecture 'Electrons in Atoms and the Periodic Table'.

Hydrogen

A reactive, diatomic element that exists as H2 and is highly reactive due to the presence of one electron in its outer shell.

Helium

An inert gas with a complete outer shell configuration, consisting of two protons and two electrons, making it stable.

Bohr Model

A model that describes electrons moving in fixed orbits around the nucleus and quantizes energy levels within those orbits.

Quantum-Mechanical Model

A model that replaces the Bohr model, representing electrons as probability maps rather than fixed orbits, explaining their locations as distributions.

Wavelength (λ)

The distance between adjacent wave crests, a defining property of light that is inversely related to frequency.

Frequency (ν)

The number of cycles or crests that pass through a stationary point in one second, inversely related to the wavelength of light.

Photon

A particle of light that carries energy; energy depends on the wavelength, with shorter wavelengths carrying greater energy.

Ionization Energy

The energy required to remove an electron from a neutral atom, which increases across a period and decreases down a group in the periodic table.

Valence Electrons

Electrons in the outermost shell of an atom that are involved in chemical bonding.

Noble Gases

Group of chemically inert elements with full valence shells, known for their minimal reactivity.

Excited State

A state of an atom where an electron has absorbed energy and moved to a higher energy level or orbital.

Core Electrons

Electrons that are not in the outermost shell and do not participate in bonding.

Atomic Emission Spectrum

The range of wavelengths emitted by an atom when its electrons transition between energy levels.

Group 1 Elements

Also known as alkali metals, these elements are highly reactive and typically lose one electron to form 1+ cations.

Group 7 Elements

Known as halogens, these elements are one electron short of a noble gas configuration, typically gaining one electron to form 1- anions.

Periodic Law

The principle stating that properties of elements repeat periodically when arranged by atomic number.

Electromagnetic Spectrum

The range of all types of electromagnetic radiation, organized by wavelength and frequency.

Diatomic Elements

Elements that naturally occur as molecules consisting of two atoms, such as hydrogen (H2) and oxygen (O2).

Excitation

The process in which an electron absorbs energy and moves to a higher energy level.

Ground State

The lowest energy state of an atom, where its electrons are in the lowest available energy levels.

Hund's Rule

A principle stating that electrons will fill degenerate orbitals singly before pairing up.

Pauli Exclusion Principle

A principle stating that no two electrons in an atom can have the same set of quantum numbers, implying opposite spins for paired electrons.

Principal Quantum Number (n)

A number that specifies the principal energy level of an orbital, indicating its size and energy.