Atoms and Radioactivity Vocabulary Flashcards

Vocabulary flashcards generated from lecture transcript covering basic atomic structure, periodic table properties, subatomic particles, isotopes, types of radiation, and radioactive decay.

Atom

The smallest continuous particle that creates an element, consisting of a central nucleus and surrounding electrons, where all atoms of a single element type share specific chemical and physical properties.

Nucleus

The infinitesimally small central region of an atom containing the bulk of the mass, composed of protons and neutrons, with a diameter of approximately $10^{-15}\,\text{m}$.

Proton

A subatomic particle located in the nucleus carrying a positive charge and defining the identity of a given element, possessing a mass of approximately $1\,\text{atomic mass unit}$ (about $1.7 \times 10^{-24}\,\text{g}$).

Neutron

A subatomic particle in the nucleus that carries no charge, possesses a mass of approximately $1\,\text{atomic mass unit}$ (slightly heavier than a proton), and adds to the mass and stability of the nucleus.

Electron

A subatomic particle that carries a negative charge and resides in the volume surrounding the nucleus, possessing a negligible mass of about $\frac{1}{1000}$ the mass of a proton or neutron.

Atomic Number

The number located at the top of an element's box on the periodic table that represents the exact number of protons in the nucleus of an atom of that element.

Mass Number

The exact total summation of the number of protons and neutrons contained within the nucleus of an individual atom.

Atomic Mass

The weighted averaging of the mass numbers for the various forms (isotopes) of a given element based on their natural relative abundances on Earth.

Isotopes

Different forms of the same element that share the same atomic number (number of protons) but possess variable numbers of neutrons in their nuclei.

Nuclear Radiation

Subatomic particles possessing mass or photons carrying electromagnetic energy that are emitted specifically from the nucleus of an atom.

Radioactive Decay

The process in which unstable isotopes emit radiation in the form of particles or energy photons into the environment to transition to a more stable state.

Radioisotopes

Unstable isotopes that exhibit radioactivity by spontaneously emitting nuclear radiation.

Alpha Particle

A form of radiation consisting of two protons and two neutrons with a $+2$ charge and a mass number of $4$ ($^{4}_{2}\text{He}$), equivalent to a helium nucleus lacking electrons.

Beta Particle

A radioactive particle carrying a $-1$ charge and negligible mass ($^{0}_{-1}\text{e}$), produced when a neutron in the nucleus ejects a negative charge and converts into a proton.

Gamma Ray

A high-energy photon of electromagnetic radiation emitted during nuclear decay that possesses no mass and no electrical charge.

Positron

A particle carrying a $+1$ charge and negligible mass ($^{0}_{1}\text{e}$), generated when an unstable proton in the nucleus loses its positive charge and converts into a neutron.

Neutron Emitter

A radioactive source that emits an uncharged subatomic particle with a mass number of $1$ and an atomic number of $0$ ($^{1}_{0}\text{n}$) directly from its nucleus.

Half-Life

The physical constant defining the amount of time required for exactly one-half of the radioactive atoms in a sample to decay into more stable nuclei.

Curie

A scientific unit used to quantify the rate of activity or amount of nuclear radiation emitted by a sample.