Introduction to Atomic Structure and Radioactive Isotopes

These flashcards cover key concepts related to atomic structure, electron configuration, nuclear radiation, and the behavior of radioactive isotopes.

Quantum mechanical model

A model of atomic structure where electrons exist in defined energy levels around the nucleus.

Valence Electrons

Electrons in an atom's outermost occupied energy level that determine chemical properties.

Electron dot structures

Diagrams that represent valence electrons as dots around the atomic symbol.

Radioactive isotopes (radioisotopes)

Atoms that emit nuclear radiation and undergo nuclear change.

Alpha particle (α)

A type of nuclear radiation consisting of two protons and two neutrons, emitted from a radioactive isotope.

Beta particle (β)

An electron emitted from the nucleus of a radioactive isotope during beta decay.

Positron (β+)

A positively charged electron emitted from a radioactive isotope during positron emission.

Gamma ray (γ)

High energy electromagnetic radiation emitted during a nuclear decay process.

Nuclear radiation

The particles and energy released during a nuclear change, including alpha and beta particles.

Max # of electrons formula

The formula for calculating the maximum number of electrons in an energy level is 2n^2.

Electron Energy Levels

Concentric shells around the nucleus where electrons reside, with increasing energy upon moving outward.

Sulfur's electrons in n=3

Sulfur has 6 electrons in its third energy level.

Balanced reactions in nuclear decay

The principle that the sum of mass numbers and charges must remain the same on both sides of the nuclear equation.

Nuclear change

The process involving a change to atomic nuclei, often resulting in the formation of new atoms.

Maximum electrons for Energy Level 1

2 electrons can fit in the first energy level.

Maximum electrons for Energy Level 2

8 electrons can fit in the second energy level.

Maximum electrons for Energy Level 3

18 electrons can fit in the third energy level.

Atom

The basic unit of matter, consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons.

Atomic Number (Z)

The number of protons in an atom's nucleus, which uniquely identifies an element.

Mass Number (A)

The total number of protons and neutrons in an atom's nucleus.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons (and thus different mass numbers).

Half-life

The time required for half of the radioactive atoms in a sample to decay.

Alpha decay

A type of radioactive decay where an atomic nucleus emits an alpha particle (_2^4He) and transforms into a new nucleus with a mass number decreased by 4 and an atomic number decreased by 2.

Beta decay

A type of radioactive decay where a neutron in the nucleus is converted into a proton, emitting a beta particle (_-1^0e) and an antineutrino, increasing the atomic number by 1 while the mass number remains the same.

Positron emission

A type of radioactive decay where a proton in the nucleus is converted into a neutron, emitting a positron (_+1^0e) and a neutrino, decreasing the atomic number by 1 while the mass number remains the same.