Atoms, Molecules, and Ions - Vocabulary Flashcards

Vocabulary flashcards defining key historical scientists, fundamental chemical laws, atomic subatomic particles, atomic models, isotopes, and bonding types from Chapter 2.

Georg Bauer

A 16th-century scientist who laid foundations for modern chemistry by developing systematic metallurgy.

Paracelsus

A 16th-century scientist who laid foundations for modern chemistry by discovering the medicinal application of minerals.

Robert Boyle

A scientist (1627–1691) who performed quantitative experiments measuring air pressure and volume, and developed the first experimental definition of an element.

Element (Boyle's Definition)

A substance that is considered an element unless it can be broken down into two or more simpler substances.

Joseph Priestley

An 18th-century scientist who discovered oxygen gas.

Georg Stahl

A scientist who suggested that phlogiston flowed out of burning material and postulated that burning stops in closed containers because air becomes saturated with phlogiston.

Antoine Lavoisier

A scientist (1743–1794) who explained the true nature of combustion, verified the law of conservation of mass, and regarded measurement as the essential operation of chemistry.

Law of Conservation of Mass

The law stating that mass is neither created nor destroyed in a chemical reaction.

Joseph Proust

A scientist (1754–1826) who proposed the principle of constant composition of compounds, also known as Proust's law or the law of definite proportion.

Law of Definite Proportion

The law stating that a given compound always contains exactly the same proportion of elements by mass.

Law of Multiple Proportions

John Dalton's law stating that when two elements form a series of compounds, the ratios of the masses of the second element that combine with $1\,\text{g}$ of the first element can always be reduced to small whole numbers.

Dalton's Atomic Theory

The theory stating that elements consist of tiny particles called atoms, atoms of a given element are identical, compounds form when atoms combine in fixed relative ratios, and chemical reactions involve atom reorganization.

Joseph Gay-Lussac

A scientist (1778–1850) who measured the volumes of gases that reacted with each other under identical temperature and pressure conditions.

Avogadro's Hypothesis

The hypothesis stating that at the same temperature and pressure, equal volumes of different gases contain the same number of particles.

J. J. Thomson

A scientist who studied cathode-ray tubes in 1897, discovered the electron, determined its charge-to-mass ratio ($\frac{e}{m} = -1.76 \times 10^8\,\text{C/g}$), and proposed the plum pudding model.

Cathode-Ray Tube

A partially evacuated tube used to study electrical discharges, which produced a stream of negatively charged particles when high voltage was applied.

Plum Pudding Model

An atomic model proposed by J. J. Thomson picturing an atom as a diffuse cloud of positive charge with negative electrons embedded randomly within it.

Robert Millikan

A scientist who conducted charged oil drop experiments to determine the magnitude of electron charge and calculated the electron mass as $9.11 \times 10^{-31}\,\text{kg}$.

Henri Becquerel

A scientist who discovered radioactivity by observing spontaneous emission of radiation by uranium on a photographic plate in the absence of light.

Gamma Rays ($\gamma$)

A form of radioactive emission consisting of high-energy light.

Beta Particles ($\beta$)

A form of radioactive emission consisting of high-speed electrons.

Alpha Particles ($\alpha$)

A form of radioactive emission with a $2+$ charge and a mass $7300$ times that of an electron.

Rutherford's Metal Foil Experiment

A 1909 experiment directing $\alpha$ particles at a thin metal foil, demonstrating that atoms are mostly open space with a massive positive central nucleus.

Proton

A nuclear subatomic particle with a positive charge equal in magnitude to an electron's negative charge ($1.60 \times 10^{-19}\,\text{C}$) and a mass of $1.673 \times 10^{-27}\,\text{kg}$.

Neutron

A nuclear subatomic particle with no charge and a mass of $1.675 \times 10^{-27}\,\text{kg}$, which is virtually equal to the mass of a proton.

Isotopes

Atoms of the same element having the same number of protons but different numbers of neutrons, displaying almost identical chemical properties.

Atomic Number ($Z$)

The number of protons in an atom's nucleus, written as a subscript in isotope notation.

Mass Number ($A$)

The total number of protons and neutrons in an atom's nucleus, written as a superscript in isotope notation.

Covalent Bond

A chemical bond formed when atoms share electrons with each other.

Structural Formula

A depiction of a molecule that shows individual bonds and may or may not represent its actual three-dimensional shape.

Space-Filling Model

A molecular model that illustrates the relative sizes of atoms and their relative orientation within a molecule.

Cation

A positively charged ion formed when a neutral atom or group of atoms loses one or more electrons.

Anion

A negatively charged ion formed when a neutral atom or group of atoms gains one or more electrons.

Ionic Bonding

The electrostatic force of attraction between oppositely charged ions.