Atoms and Subatomic Particles Review

Flashcards covering Bohr’s atom, the periodic table, electron configuration, valence electrons, the Octet Rule, and periodic trends.

Bohr's Atom

A model describing the positively-charged nucleus containing protons surrounded by electrons in fixed energy levels or orbits.

Quantization of Energy

The concept that electrons exist in fixed energy levels surrounding the nucleus.

Excited state (electron)

The state an electron is in when it has absorbed energy and moved to a higher energy level.

Relaxation (electron)

The process where an electron travels back to lower energy levels, releasing energy, often in the form of a photon of light.

Ground state

The lowest energy level(s) possible for an atom's electrons.

Orbit (Bohr's Theory)

Bohr's term for the fixed energy levels where electrons are found.

Atomic orbital

A specific region of a sub-level containing a maximum of two electrons, a refinement to Bohr's theory.

Dmitri Mendeleev & Lothar Meyer

Scientists who independently developed the precursor to the modern Periodic Table based on atomic mass.

Periodic Law

The principle stating that the physical and chemical properties of the elements are periodic functions of their atomic numbers.

Periodic Table

A visual representation of the periodic law, organizing elements by atomic number and properties.

Atomic number

The number of protons in an element, which uniquely distinguishes all elements.

Period (Periodic Table)

A horizontal row of elements in the periodic table.

Groups (or families)

Vertical columns of elements in the periodic table whose elements share many similar properties.

Representative elements (Group A)

Elements belonging to Groups 1-2 and 13-18 of the periodic table.

Transition elements (Group B)

Elements belonging to Groups 3-12 of the periodic table.

Alkali metals

The common name for elements in Group 1 (or IA) of the periodic table.

Lanthanide series

A series of 14 elements chemically and physically similar to lanthanum, inserted in Period 6 of the periodic table.

Actinide series

A series of 14 elements similar to actinium, inserted in Period 7 of the periodic table.

Metals

Elements that tend to lose electrons, characterized by malleability, ductility, high thermal/electrical conductivity, and lustre.

Non-Metals

Elements that tend to gain electrons and form ionic species (anions), characterized by poor conductivity, dullness, and brittleness.

Metalloids (semi-metals)

Elements with properties similar to both metals and non-metals, such as silicon.

Quantum mechanics

Erwin Schrödinger's theory that refined Bohr's model, incorporating principal energy levels, sub-levels, and atomic orbitals.

Principal Energy Levels (shells)

Regions where electrons may be found, assigned integer values (n = 1, 2, 3, …) and related to distance from the nucleus.

Sub-levels (sub-shells)

A set of energy-equal orbitals within a principal energy level, designated as s, p, d, and f, increasing in energy in that order.

Electron Configuration

The arrangement of electrons in atomic orbitals within an atom.

Aufbau Principle

A principle stating that electrons fill the lowest-energy orbital that is available first (s < p < d < f).

Pauli Exclusion Principle

A principle stating that each atomic orbital can hold a maximum of two electrons, and these electrons must have opposite spins.

Hund’s Rule

A rule stating that each orbital in a sub-level is half-filled (with one electron) before any orbital becomes completely filled (with two electrons).

Shorthand Electron Configurations

An abbreviated way to write electron configurations using the symbol of the preceding noble gas to represent inner electrons.

Valence Electrons

Electrons in the outermost shell of an atom that are involved, or have the potential to be involved, in chemical bonding.

Octet Rule

The principle that elements usually react to attain eight electrons in their outermost (valence) shell, achieving stability similar to noble gases.

Ions

Electrically charged particles that result from a gain or loss of one or more electrons by a parent atom.

Cation

A positively charged ion that results from the loss of electrons by a parent atom.

Anion

A negatively charged ion that results from the gain of electrons by a parent atom.

Atomic Size Trend

Increases down a group (valence shell is farther from nucleus) and decreases across a period (increased nuclear charge pulls electrons closer).

Cation Size

Generally smaller than their parent atom due to the loss of valence electrons and increased nuclear charge effectively pulling remaining electrons closer.

Anion Size

Generally larger than their parent atom due to the gain of electrons, which increases electron-electron repulsion and reduces the nucleus's pull on each electron.

Ionization Energy

The energy required to remove an electron from an isolated atom, decreasing down a group and increasing across a period.

Electron Affinity

The energy released when a single electron is added to an isolated atom, generally decreasing down a group and increasing across a period.