Atomic Structure Concepts
13 concepts · Grades 6-8, 9-12 · 19 prerequisite connections
This family view narrows the full chemistry map to one connected cluster. Read it from left to right: earlier nodes support later ones, and dense middle sections usually mark the concepts that hold the largest share of future work together.
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Concepts flow left to right, from foundational to advanced. Hover to highlight connections. Click any concept to learn more.
Connected Families
Atomic Structure concepts have 10 connections to other families.
All Atomic Structure Concepts
Atom
The smallest unit of an element that retains the chemical properties of that element.
Element
A pure substance consisting entirely of atoms with the same number of protons (same atomic number), which cannot be broken down into simpler substances by any chemical reaction. There are 118 known elements, organized in the periodic table.
Proton
A positively charged subatomic particle found in the nucleus of every atom, whose count defines the element's identity.
Neutron
A neutral subatomic particle found in the nucleus of an atom that has no electric charge but contributes to the atom's mass.
Electron
A negatively charged particle found outside the nucleus, occupying energy shells around the atom.
Atomic Number
The number of protons in an atom's nucleus, which uniquely identifies the element.
Mass Number
The total count of protons and neutrons (collectively called nucleons) in an atom's nucleus, always a whole number, used to identify specific isotopes of an element.
Isotope
Atoms of the same element that have the same number of protons but different numbers of neutrons, giving them different mass numbers.
Electron Shell
A discrete energy level surrounding the atomic nucleus where electrons reside, with each shell ($n = 1, 2, 3, ...$) holding a maximum of $2n^2$ electrons. Lower shells have less energy and fill first.
Valence Electron
An electron residing in the outermost (highest-energy) occupied shell of an atom, available for participation in chemical bonding through sharing, gaining, or losing. The number of valence electrons determines an element's bonding behavior and chemical reactivity.
Ion
An atom or group of atoms that has gained or lost one or more electrons, resulting in a net positive charge (cation) or net negative charge (anion). The number of protons remains unchanged; only the electron count changes.
Electron Configuration
The arrangement of electrons in an atom's orbitals, described using quantum numbers and subshell notation.
Radioactivity
The spontaneous emission of particles or energy from an unstable atomic nucleus.