Physical Science: Nucleosynthesis, Atomic Theory, Element Synthesis, and Electronegativity

Vocabulary practice flashcards covering nucleosynthesis, stellar evolution, Big Bang theory, historical atomic theories, synthesis of transuranium elements, and molecular electronegativity.

Stellar Nucleosynthesis

The process by which chemical elements heavier than beryllium are formed within stars through nuclear fusion reactions.

Stellar Evolution

The sequence of radical changes that a star undergoes during its lifetime, primarily determined by its initial mass.

Protostar

A superhot, contracting stellar core formed from fragmented clumps of a collapsing nebula or molecular cloud before nuclear fusion begins.

Main Sequence Star

A star in gravitational equilibrium where core contraction has halted due to the outward pressure generated by hydrogen fusion into helium via proton-proton chain reactions.

Brown Dwarf

A substellar object with insufficient mass to sustain hydrogen fusion, capable only of briefly sustaining deuterium fusion reactions before cooling over hundreds of millions of years.

Red Giant

A luminous evolved star formed when core hydrogen is depleted; helium burns to carbon in the core via alpha processes while hydrogen fusion continues in an outer shell, expanding the outer layers.

White Dwarf

The dense, hot, and inert carbon or carbon-oxygen remnant left behind by a low-mass star after its outer layers are expelled into space as a planetary nebula.

Multiple-Shell Red Giant

An evolved massive star characterized by concentric fusion shells fusing sequentially heavier elements (carbon to oxygen, oxygen to neon, neon to silicon, and silicon to iron).

Supernova

A cataclysmic stellar explosion triggered when a massive star's core can no longer resist gravitational collapse, producing high-energy neutrinos and neutrons that synthesize elements heavier than iron.

Extinction (Astronomy)

The absorption and scattering of electromagnetic radiation by interstellar gas and dust particles positioned between an emitting celestial body and an observer.

Physical Cosmology

The branch of science that studies the physical origin, large-scale structures, evolution, and ultimate fate of the universe using observational data and scientific laws.

Creatio Ex Nihilo

A cosmological and philosophical concept describing the creation of all matter in the universe out of nothing by a creator deity.

Redshift

The phenomenon observed by Vesto Slipher and Carl Wilhelm Wirtz wherein the spectral lines of light from distant spiral galaxies are shifted toward longer wavelengths, indicating expansion and recession from Earth.

Cosmic Microwave Background Radiation (CMBR)

A faint, uniform thermal radiation filling the universe, discovered in $1965$ by Robert Wilson and Arno Penzias as remnant energy from the Big Bang.

Singularity

An infinitely dense, extremely hot initial point containing all space, time, matter, and energy prior to the rapid inflationary expansion of the universe.

Annihilation

A high-energy reaction in which a matter particle collides with its corresponding antimatter counterpart, destroying both and converting their mass back into pure radiation energy.

Recombination

The primordial epoch in the cooling universe during which free electrons bound with ionized atomic nuclei to form neutral atoms.

Big Bang Nucleosynthesis (BBN)

The production of primordial light nuclei—specifically isotopes of hydrogen, helium, lithium, and beryllium—within the first few minutes after the Big Bang expansion.

Deuterium Bottleneck

The early phase of the universe where high temperatures and energetic photons disintegrated newly formed deuterium ($^2\text{H}$) until temperatures dropped below the threshold required for its stability.

Binding Energy

The quantity of energy required to disassemble an intact atomic nucleus into its individual constituent protons and neutrons.

Chondrites

Primitive, un-melted stony meteorites that preserve the ancient chemical compositions and primordial elemental ratios of the early solar system.

Atomos

The ancient Greek concept proposed by Leucippus and Democritus defining the ultimate, indivisible, and indestructible building blocks of all matter.

Law of Conservation of Mass

The fundamental scientific law formulated by Antoine Lavoisier stating that mass can neither be created nor destroyed in a chemical reaction within an isolated system.

Dalton's Atomic Theory

The early chemical theory proposed by John Dalton stating that all matter is made of indivisible atoms, that atoms of a given element are identical in mass and properties, and that compounds form in small whole-number ratios.

Law of Definite Proportions

A chemical law established by Joseph Proust in $1806$ stating that any given chemical compound always contains its constituent elements in fixed, unvarying ratios by mass.

Law of Multiple Proportions

A chemical law formulated by John Dalton stating that when two elements form more than one compound, the varying masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers.

Binary Compound (Dalton)

In John Dalton's system, a compound consisting of the pairing of exactly two atoms, such as carbon monoxide ($\text{CO}$) or diatomic nitrogen ($\text{N}_2$).

Ternary Compound (Dalton)

In John Dalton's system, a compound formed from the chemical union of three atoms, such as nitrogen dioxide ($\text{NO}_2$).

Daltonism

A form of congenital color blindness named after John Dalton, who experienced the condition and described it scientifically.

Atomic Number ($Z$)

The fundamental property of an atom indicating its total number of protons and nuclear charge, derived from the German word Zahl, which uniquely dictates the element's identity and properties.

X-ray Spectroscopy

An analytical method developed by Henry Moseley involving bombarding elemental targets with electrons to measure their characteristic X-ray frequencies, mathematically correlating spectral lines to atomic number.

Nuclear Transmutation Reaction

A nuclear process involving the conversion of one chemical element or isotope into another, first accomplished by Ernest Rutherford in $1919$ by bombarding nitrogen with alpha particles.

Particle Accelerator

An electromagnetic apparatus that accelerates subatomic particles to relativistic speeds, enabling them to overcome electrostatic repulsive forces and induce nuclear reactions with target nuclei.

Cyclotron

A compact particle accelerator invented by Ernest Lawrence that employs an alternating electric field and a magnetic field to accelerate charged particles along an expanding spiral trajectory.

Technetium ($\text{Tc}$)

The first artificially synthesized chemical element ($Z = 43$), discovered in $1937$ by Carlo Perrier and Emilio Segrè from cyclotron components and named after the Greek word technêtos ('artificial').

Astatine ($\text{At}$)

A synthetic radioactive halogen ($Z = 85$) produced in $1940$ by Dale Corson, Kenneth Mackenzie, and Emilio Segrè by bombarding bismuth ($Z = 83$) with alpha particles, named from astatos ('unstable').

Transuranium Elements

The synthetic, radioactive chemical elements that possess atomic numbers greater than $92$ ($Z > 92$, beyond uranium), produced via particle accelerators or nuclear reactors.

Electronegativity ($\chi$)

A relative chemical measure of an atom's tendency to attract shared electron pairs toward itself within a covalent bond.

Pauling Electronegativity Scale

A numerical scale formulated by Linus Pauling based on thermochemical bond dissociation energies, ranking elements according to their electron-attracting power in bonds.

Electron Affinity

The measure of energy released when an electron is added to an isolated gaseous neutral atom, differing from electronegativity which measures attraction in a chemical bond.

Electronegativity Difference ($\Delta\chi$)

The absolute value of the difference between the electronegativity values of two bonded atoms ($\Delta\chi = |\chi_1 - \chi_2|$), utilized to describe the polarity of a chemical bond.