Atomic Structure Practice Flashcards

These vocabulary flashcards cover the fundamental concepts of atomic history, subatomic particles, ionization energy trends, and electronic configurations based on the lecture transcript.

Atom

The smallest part of an element that can take part in a chemical change.

Proton

A positively charged particle found in the nucleus of an atom, with a relative charge of $+1$ and a relative mass of $1$.

Neutron

An uncharged particle found in the nucleus of an atom, with a relative charge of $0$ and a relative mass of $1$, the same as a proton.

Electron

A negatively charged particle found in orbitals outside the nucleus with a relative charge of $-1$ and a negligible mass compared to a proton.

Nucleus

The small, dense, positively charged center of an atom that contains protons and neutrons.

Atomic Number ($Z$)

The number of protons in the nucleus of an atom, which defines the identity of the element.

Mass Number ($A$)

The total number of protons and neutrons in the nucleus of an atom, also referred to as the nucleon number.

Molecule

Two or more atoms that are chemically bonded together.

Demokritos

A Greek philosopher who proposed over 2000 years ago that all matter consists of very tiny, indivisible particles called atoms.

John Dalton

A scientist who provided experimental support for atoms, proposing that atoms of the same element have the same mass and that chemical reactions are the rearrangement of atoms.

Plum Pudding Model

J.J. Thomson's 1904 model describing the atom as a uniform sphere of positive charge with negatively charged electrons embedded within it.

Rutherford's Gold Foil Experiment

A 1911 experiment firing alpha particles at thin gold foil, which revealed that atoms are mostly empty space with a tiny, dense nucleus.

Bohr's Atomic Model

A 1913 model that applied quantum theory to explain that electrons revolve around the nucleus in specific, quantized orbits or energy levels.

Nanotechnology

A field focused on designing and building structures at the scale of atoms and molecules, involving objects only a few thousand atoms thick or smaller.

Chemical Element

A substance containing only one type of atom that cannot be broken down into simpler substances by chemical methods.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Ion

An electrically charged particle formed when an atom gains or loses electrons.

Electronic Configuration

The arrangement of electrons in different sub-shells and principal quantum shells of an atom or ion.

Principal Quantum Number ($n$)

A numbering system ($n = 1, 2, 3, \text{etc.}$) used to label principal energy levels according to their distance from the nucleus.

Orbital

A region of space outside the nucleus where there is a high probability of finding a particular electron, holding a maximum of two electrons.

Sub-shell

Regions within principal quantum shells named $s, p, d,$ and $f$, which represent different energy levels and orbital shapes.

First Ionisation Energy ($IE_1$)

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous $1^{+}$ ions.

Shielding Effect

The repulsion of outer shell electrons by inner shell electrons, which reduces the effective nuclear attraction on the outer electrons.

Spin-Pair Repulsion

The repulsion that occurs when two electrons occupy the same orbital, making them slightly easier to remove than unpaired electrons.

Atomic Radius

A measure of the size of an atom, often defined as half the distance between the nuclei of two bonded atoms.

Ionic Radius

The size of an ion; it decreases for cations as they lose electrons and increases for anions due to increased electron-electron repulsion.

Free Radical

A chemical species that possesses one or more unpaired electrons, making it highly reactive.

Successive Ionisation Energies

The energy values required to remove electrons one by one from an atom; large jumps between values indicate a change in principal quantum shells.

s Orbital

A spherical-shaped orbital found in every principal quantum shell.

p Orbital

An hourglass-shaped orbital (with two lobes) oriented along the $x, y,$ or $z$ axis; there are three such orbitals in every $p$ sub-shell.