Atomic Theory, Atomic Structure, and the Periodic Table

Vocabulary flashcards defining fundamental concepts of atomic structure, subatomic particles, atomic forces, periodic table notation, and isotopes.

Atom

The smallest unit of an element that still retains the properties of that element.

Element

A pure substance that cannot be broken down into anything simpler or more stable.

Atomic Theory

The concept that matter is composed of fundamental particles called atoms.

Proton

A positively charged subatomic particle ($+1$) located in the nucleus that determines the identity of an atom.

Neutron

A neutral subatomic particle ($0$) located in the nucleus that contributes to mass and stability without affecting charge.

Electron

A negatively charged subatomic particle ($-1$) located in constant motion outside the nucleus that determines bonding behavior and volume.

Nucleus

The dense center of an atom composed of protons ($p^+$) and neutrons ($n^0$), possessing an overall positive charge and containing nearly all of the atom's mass.

Electron Cloud

The space surrounding the nucleus filled with electrons in constant motion, having an overall negative charge and responsible for the atom's volume.

Valence Electrons

The electrons located in the outermost shell or energy level of an atom's electron cloud.

Electromagnetic Force

The force of attraction and repulsion between positive and negative charges that holds the electron cloud in place around the positive nucleus.

Strong Nuclear Force

The attractive force holding the nucleus together despite proton repulsion, driven by the strong attraction between quarks.

Quarks

The smallest known fundamental particles that make up both protons and neutrons.

Atomic Number

The number of protons ($p^+$) in an atom, which identifies the element and is found on the periodic table.

Average Atomic Mass

The weighted average mass of all known isotopes of an element, measured in atomic mass units ($amu$) and listed on the periodic table.

Mass Number

The sum of the protons ($p^+$) and neutrons ($n^0$) in an individual atom, which is not found on the periodic table.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Hyphen Form

A method of isotope notation written as the element name followed by a hyphen and the mass number (e.g., Potassium-40).

Nuclear Form

A method of isotope notation written with the mass number as a superscript to the left of the chemical symbol (e.g., $^{40}\text{K}$).