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The 174 pages that link to Atomic number, each with the reason it gives.

• ActiniumRelated: Actinium’s 89 protons distinguish it from every other element.

• AmericiumRelated: Americium’s 95 protons distinguish it from every other element.

• ChalcogenRelated: Atomic number orders group 16 from oxygen to livermorium.

• Frederick SoddyRelated: Soddy’s isotope concept distinguished elemental identity from atomic weight.

• OsmiumRelated: Osmium is element 76 because every osmium nucleus contains 76 protons.

• AstatineRelated: Astatine's 85 protons distinguish it from every other element.

• CaliforniumRelated: Californium’s 98 protons distinguish it from neighboring elements.

• Element naming controversyRelated: Evidence for a new element must establish a previously unknown atomic number.

• Isotopes of hydrogenRelated: All hydrogen isotopes have atomic number one.

• LawrenciumRelated: Lawrencium's 103 protons distinguish it from every other element.

• Rubidium-87Related: Its 37 protons identify rubidium-87 as rubidium.

• BerkeliumRelated: Berkelium's 97 protons define its position in the periodic table.

• FranciumRelated: Francium’s atomic number, 87, defines its identity.

• GadoliniumRelated: Gadolinium’s atomic number, 64, distinguishes it from every other element.

• Lead(II) ionRelated: Lead’s atomic number, 82, remains unchanged when its atoms form Pb²⁺.

• NiobiumRelated: The atomic number 41 uniquely identifies niobium.

• ProtiumRelated: Protium’s single proton gives it hydrogen’s atomic number of one.

• EuropiumRelated: Europium’s atomic number 63 distinguishes it from every other element.

• HafniumRelated: Hafnium’s 72 protons distinguish it from every other element.

• LutetiumRelated: Lutetium’s 71 protons distinguish it from every other element.

• RheniumRelated: Rhenium’s 75 protons distinguish it from every other element.

• CaesiumRelated: Caesium’s 55 protons distinguish it from every other element.

• DubniumRelated: Dubnium's 105 protons define its identity as element 105.

• EinsteiniumRelated: Ninety-nine protons distinguish einsteinium from every other element.

• Group 10 elementRelated: Atomic number fixes the sequence from nickel through darmstadtium in the group.

• Isotopes of oxygenRelated: Every oxygen isotope has atomic number eight.

• UnquadpentiumRelated: The number 145 determines both the hypothetical element's identity and its systematic name.

• Group 11 elementRelated: Atomic number sets the sequence that places copper, silver, gold, and roentgenium in the column.

• History of atomic theoryRelated: It replaced atomic mass as the fundamental identifier of an element.

• MeitneriumRelated: The value 109 distinguishes meitnerium from every other element.

• MendeleviumRelated: Mendelevium’s 101 protons distinguish it from neighboring elements.

• Period 3 elementRelated: Period 3 runs consecutively from atomic number 11 to 18.

• ThalliumRelated: Thallium’s 81 protons distinguish it from every other element.

• Helium atomRelated: Helium’s atomic number is two, fixing its identity across all isotopes.

• History of the periodic tableRelated: Ordering elements by proton count resolved conflicts in weight-based arrangements.

• Period 2 elementRelated: Increasing atomic number from 3 to 10 orders the elements across this period.

• Period 7 elementRelated: Atomic number orders period 7 from francium through oganesson.

• ProtactiniumRelated: Protactinium's 91 protons distinguish it from every other element.

• UnpentquadiumRelated: The value 154 specifies the proton count that defines this hypothetical element.

• Whole-number ruleRelated: It fixes one part of the nucleus's integer particle count.

• Atomic propertiesRelated: Proton count determines elemental identity and shapes the atom’s electron arrangement.

• BohriumRelated: The value 107 distinguishes bohrium from every other element.

• Charles BarklaRelated: Characteristic X-ray frequencies vary systematically with the element’s atomic number.

• Decay productRelated: Changes in proton number determine whether a product is a new element.

• Group 3 elementRelated: Atomic number fixes the sequence in which Group 3 candidates appear.

• Isotopes of nitrogenRelated: Nitrogen's atomic number remains seven across all its isotopes.

• Isotopes of uraniumRelated: Every uranium isotope has atomic number 92, regardless of its neutron count.

• Period 1 elementRelated: The two elements in Period 1 have atomic numbers 1 and 2.

• Primordial nuclideRelated: It distinguishes elements while neutron number distinguishes their nuclides.

• UnbienniumRelated: The number 129 fixes which hypothetical element Unbiennium names.