Inside the Atom: Protons, Neutrons, and Electrons

Flashcards covering fundamental atomic concepts, subatomic particles, isotope notation, and atomic structure rules from Chemistry Chapter 5.

Atomic Number

The number that increases uniformly from left to right across the periodic table, representing the total number of protons in an atom's nucleus.

Mass Number

The total count of protons and neutrons ($\text{P} + \text{N}$) contained inside the nucleus of an atom.

Nucleus

The central region of an atom where virtually all of the atomic mass is concentrated.

Isotope

Atoms of the same element that share the same number of protons but have different numbers of neutrons.

Neutron Calculation

The mathematical method used to find the number of neutrons in an atom by subtracting the atomic number from the mass number ($\text{Mass Number} - \text{Atomic Number}$).

Average Atomic Mass

The decimal value listed on the periodic table that represents the weighted average mass of all naturally occurring isotopes of an element.

Isotope Notation

A standard format where the mass number is placed in the upper left-hand corner and the atomic number is placed in the lower left-hand corner of the chemical symbol (e.g., $^{12}_{6}\text{C}$).

Carbon-12

A specific carbon isotope denoted as $^{12}_{6}\text{C}$, characterized by an atomic number of $6$ and a mass number of $12$.

Potassium-39

An isotope of potassium ($\text{K}$) containing an atomic number of $19$ and a mass number of $39$, written in isotopic notation as $^{39}_{19}\text{K}$.

Chlorine-36

An isotope of chlorine ($\text{Cl}$) containing an atomic number of $17$ and a mass number of $36$, written in isotopic notation as $^{36}_{17}\text{Cl}$.

Mass Number vs. Atomic Number Pattern

The periodic trend observed for all elements beyond hydrogen where the mass number is consistently larger than the atomic number.

Proton

A subatomic particle located within the atomic nucleus whose total count defines the element's atomic number.

Electron

A subatomic particle whose count in a neutral atom equals the number of protons and the atomic number.