Structure of the Atom Practice Flashcards

Comprehensive vocabulary flashcards covering the history of atomic discovery, modern atomic theory, classification of atoms, bonding types, ionization, and radioactivity based on the provided lecture notes.

Leucippus

The figure most often associated with the earliest atomic theory.

Democritus of Abdera

Greek philosopher ($460-370$ BCE) who provided detailed expansion on the earliest atomic theory and believed atoms were indestructible.

Atomos

The Greek word meaning "indivisible" from which the term atom is derived.

The Four Essences

According to early Greeks, the four basic qualities (wet, dry, hot, and cold) that modified the four basic substances of matter.

John Dalton

English chemist who in $1808$ developed a sound atomic theory based on scientific evidence, stating elements are composed of unique atoms.

Dmitri Mendeleev

Scientist who advanced atomic theory by organizing known elements into a periodic table based on atomic mass and similar chemical properties.

Joseph John “J.J.” Thomson

Scientist who discovered the electron in $1890$ while studying cathode ray tubes and developed the plum pudding model.

Ernest Rutherford

Scientist who in $1911$ conducted experiments with alpha particles and proposed a model of the atom resembling a tiny solar system.

Niels Bohr

Scientist who in $1913$ proposed a modern atomic theory where atoms have three fundamental particles and electrons revolve in fixed orbits.

Fundamental Particles

The three components of an atom: protons, neutrons, and electrons.

Nucleon

A term for the particles contained in the nucleus, specifically protons and neutrons.

Quarks and Gluons

The components that make up a nucleon; quarks are held together by gluons.

Neutral Atom

An atom where the number of electrons is equal to the number of protons in the nucleus.

Atomic Mass Unit (AMU)

A measurement defined as the mass of a proton.

Anion

A negative ion formed when negative charges (electrons) outnumber the positive charges (protons).

Cation

A positive ion formed when positive charges outnumber the negative charges.

Binding Energy

A measure of the energy needed to split an atom; it creates a strong attraction in the nucleus to hold protons and neutrons together.

Atomic Number (Z)

The number of protons found in an atom; for example, Oxygen has an atomic number of $8$.

Electron Shells

Defined energy levels located at different distances from the nucleus where electrons orbit.

Centripetal Force

The force resulting from the attraction of opposite charges that maintains an electron's position in its orbit.

Centrifugal Force

The force that helps electrons maintain their distance from the nucleus by traveling in a circular or elliptical path.

Electron Shell Lettering

The naming convention for electron shells starting with "K" nearest the nucleus, followed by "L", "M", "N", "O", and "P".

Electron Shell Limit Formula

The formula used to determine the maximum number of electrons a shell can hold: $2n^2$, where $n$ is the shell number.

Molecules

Structures formed when atoms of various elements combine; these can further combine to form cells and tissues.

Compound

A structure formed by two or more atoms of different elements that bond together; the smallest particle of a compound is a molecule.

Isotopes

Atoms with the same number of protons but a different number of neutrons (same atomic number, different atomic mass).

Isotones

Atoms with the same number of neutrons but a different number of protons.

Isobars

Atomic nuclei that have the same atomic mass number but different atomic numbers (different number of protons).

Isomers

Identical atoms with the same atomic number and atomic mass number that exist at different energy states due to nucleon arrangement.

Ionic Bonding

A chemical bond based on the attraction of opposing charges where one atom gives up an electron and another takes an extra electron.

Covalent Bonding

The most common form of chemical bonding where atoms share unpaired electrons, often described as a "figure-$8$" pattern.

Ionization

The process of adding or removing an electron from an atom, which results in an atom that is no longer neutral.

Ion Pair

The result of an ionization interaction, consisting of the ejected negative electron and the remaining positive ion.

Radioactivity

The spontaneous emission of particles and energy by radionuclides in order to become stable; also known as Radioactive Decay.

Radioactive Half-Life

The time required for a quantity of radioactivity to be reduced to one-half ($1/2$) of its original value.

Curie (Ci)

The unit used for measuring radioactive material.

Beta Emission

Radioactive decay where an electron created in the nucleus is ejected, conversion of a neutron to a proton occurs, and the atomic number increases by $1$. ($Z \rightarrow Z+1$).

Alpha Emission

Radioactive decay occurring in extremely unstable nuclei where an alpha particle ($2$ protons and $2$ neutrons) is emitted, losing $4$ amu of mass.

Gamma Rays

Electromagnetic radiation consisting of photons that are emitted from the nucleus of a radioisotope.

X-Rays

Electromagnetic radiation produced outside the nucleus in the electron shells.