Structure 1.2 The Nuclear Atom and Mass Spectrometry Flashcards

Vocabulary flashcards covering atomic structure, subatomic particles, historical atomic models, isotopes, and mass spectrometry based on IB Chemistry topic S1.2.

Nucleon

A proton or neutron located inside the nucleus of an atom.

Atomic number ($Z$)

The number of protons in the nucleus of an atom, which uniquely identifies the element.

Mass number ($A$)

The total number of protons and neutrons present in the nucleus of an atom.

Isotope

Atoms of the same element that contain the same atomic number ($Z$) but different mass numbers ($A$) due to a different number of neutrons.

Radioisotope

An isotope of an element that possesses an unstable nucleus and emits radiation as it decays to attain nuclear stability.

Relative atomic mass ($A_r$)

The weighted average of the masses of the naturally occurring isotopes of an element relative to $\frac{1}{12}$ of the mass of a carbon-12 atom.

Natural abundance ($NA$)

The percentage of atoms of a specific isotope found naturally in a sample of an element.

Proton

A positively charged subatomic particle located in the nucleus with a relative charge of $+1$ and a relative mass of approximately $1$.

Neutron

A neutral subatomic particle located in the nucleus with a charge of $0$ and a relative mass of approximately $1$.

Electron

A negatively charged subatomic particle located outside the nucleus in the electron cloud, with a relative charge of $-1$ and a relative mass of approximately $\frac{1}{1836}$.

Atomic radius vs. Nuclear radius

The atomic radius is on the order of $10^{-10}\text{ m}$, whereas the nuclear radius is on the order of $10^{-14}\text{ m}$.

Plum Pudding Model

An atomic model proposed by J.J. Thomson in which negatively charged electrons are embedded within a sphere of positive charge.

Rutherford's Nuclear Model

An atomic model established following the gold foil experiment, demonstrating that an atom consists mostly of empty space with its positive charge and mass concentrated in a tiny central nucleus.

Bohr's Atomic Model

An atomic model proposing that electrons travel around the nucleus in fixed circular orbits corresponding to quantized energy levels.

Quantum Mechanical Model

The modern atomic model formulated by Erwin Schrödinger where electrons exist in probability clouds called orbitals rather than defined planetary paths.

Atomic orbital

A region in space around the nucleus (such as s, p, d, or f) where there is a $90\text{\%}$ probability of finding an electron of a specific energy level.

Mass spectrometry

An analytical technique used to determine relative atomic masses and isotopic composition by vaporizing, ionizing, accelerating, and deflecting particles based on their mass and charge.

Mass-to-charge ratio ($m/z$)

The ratio of the mass number of an ion to its charge state, recorded by the detector in mass spectrometry.

Fragmentation pattern

The characteristic pattern of smaller ionic pieces formed when molecules break apart inside a mass spectrometer, used to determine molecular structure.

Atomic mass unit ($\text{amu}$)

A unit of mass defined such that $1\text{ amu} = 1.660539 \times 10^{-24}\text{ g}$.