Atomic Structure & Nuclear Chemistry Flashcards

Flashcards about Atomic Structure & Nuclear Chemistry: Models of the Atom, Subatomic Particles, Atomic Mass, Nuclear Radiation & Equations, Half-Life, Uses & Applications of Nuclear Chemistry

Atom

The smallest identifiable unit of an element.

Element

A substance that cannot be broken down into simpler substances.

Atomos

Tiny, indestructible particles that make up matter, according to Democritus.

Dalton's Atomic Theory - Part 1

Each element is composed of tiny, indestructible particles called atoms.

Dalton's Atomic Theory - Part 2

All atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements.

Dalton's Atomic Theory - Part 3

Atoms combine in simple, whole-number ratios to form compounds.

Electron

A smaller and more fundamental particle inside the atom discovered by J.J. Thomson.

Thomson's Discoveries about Electrons

Electrons are negatively charged, much smaller and lighter than atoms, and uniformly present in many different kinds of substances.

Plum-Pudding Model

Negatively charged electrons are held in a sphere of positive charge.

Rutherford’s Gold Foil Experiment Results

Most of the alpha particles passed directly through the foil; a few were deflected at sharp angles. Conclusion: the atom is mostly empty space with a dense, positively charged nucleus.

Nucleus

Dense, positively charged — at atom’s core — contains protons and neutrons.

Bohr Model

Planetary Model: Electrons travel around the nucleus in circular orbits only at specific, fixed distances from the nucleus.

Orbitals

Electrons are likely to be found.

Neutrons

Neutral particles in the nucleus of the atom.

Atomic Mass Unit (amu)

One-twelfth of the mass of the carbon atom with 6 protons and 6 neutrons.

Atomic Mass Unit

A relative scale used to express the mass of atoms.

Electrical Charge

A fundamental property of protons and electrons.

Atomic Number (Z)

Number of protons in the nucleus of an atom.

Mass Number

Number of protons + the number of neutrons.

Isotopes

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

Mass Number (A)

The sum of the number of protons (Z) and the number of neutrons.

Isotope Notation

Chemical symbol (or chemical name) followed by a hyphen and the mass number of the isotope.

Ions

Atoms often lose or gain electrons to form charged particles.

Cations

Positive Ions

Anions

Negative Ions

Ion Charge

The charge of an ion depends on how many electrons were gained or lost.

Atomic Mass

Calculated based on the weighted average of all naturally occurring isotopes.

Radioactivity

The spontaneous emission of rays/particles from certain elements.

Nuclear Radiation

The rays/particles emitted from a radioactive element; the process of emitting is called a nuclear reaction.

Radioisotopes

Unstable isotopes.

Radioactive Decay

A spontaneous process that does not require the input of energy.

Alpha (α) particles

Identical to a helium nucleus.

Beta (β) particles

High-energy electrons.

Gamma (γ) rays

Pure energy.

Alpha (α) particle

A helium nucleus with 2 protons, 2 neutrons, a mass number of 4, and a charge of 2+.

Beta (β) particle

A high-energy electron with a mass number of 0 and a charge of 1-.

Positron (β+)

Equivalent to a positive electron with a mass number of 0 and a charge of 1+.

Gamma (γ) ray

High-energy radiation with a mass number of 0 and a charge of 0.

Ionizing Power

The ability of radiation to ionize molecules and atoms.

Penetrating Power

The ability of radiation to penetrate matter.

Half-Life

The time for the radiation level to decrease to one-half of its original value.

Transmutation

The conversion of an atom of one element into an atom of another element.

Nuclear Fission

A large nucleus is bombarded with a small particle.

Mass Defect

Missing mass converted to energy.

Chain Reaction

A rapid increase in the number of high-energy neutrons available to react with more uranium.

Nuclear Fusion

Combines small nuclei into larger nuclei.

Ionizing Radiation

Radiation emitted by radioisotopes that has enough energy to knock electrons off some atoms of a bombarded substance producing ions.