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Start with the full category, then apply the exact boundary: The first 30 elements. Element names and chemical symbols both count. You only need one qualifying answer. A longer name is not automatically rarer.
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CobaltCobalt (Co) has atomic number 27 on the IUPAC periodic table.
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ScandiumScandium (Sc) has atomic number 21 on the IUPAC periodic table.Aliases: Sc
96VanadiumVanadium (V) has atomic number 23 on the IUPAC periodic table.Aliases: V
94ManganeseManganese (Mn) has atomic number 25 on the IUPAC periodic table.Aliases: Mn
89BerylliumBeryllium (Be) has atomic number 4 on the IUPAC periodic table.Aliases: Be
88CobaltCobalt (Co) has atomic number 27 on the IUPAC periodic table.Aliases: Co
83ArgonArgon (Ar) has atomic number 18 on the IUPAC periodic table.Aliases: Ar
78ChromiumChromium (Cr) has atomic number 24 on the IUPAC periodic table.Aliases: Cr
77FluorineFluorine (F) has atomic number 9 on the IUPAC periodic table.Aliases: F
74BoronBoron (B) has atomic number 5 on the IUPAC periodic table.Aliases: B
72PhosphorusPhosphorus (P) has atomic number 15 on the IUPAC periodic table.Aliases: P
68NickelNickel (Ni) has atomic number 28 on the IUPAC periodic table.Aliases: Ni
64SulfurSulfur (S) has atomic number 16 on the IUPAC periodic table.Aliases: S · Sulphur
60TitaniumTitanium (Ti) has atomic number 22 on the IUPAC periodic table.Aliases: Ti
59ZincZinc (Zn) has atomic number 30 on the IUPAC periodic table.Aliases: Zn
57MagnesiumMagnesium (Mg) has atomic number 12 on the IUPAC periodic table.Aliases: Mg
54PotassiumPotassium (K) has atomic number 19 on the IUPAC periodic table.Aliases: K
52ChlorineChlorine (Cl) has atomic number 17 on the IUPAC periodic table.Aliases: Cl
50SiliconSilicon (Si) has atomic number 14 on the IUPAC periodic table.Aliases: Si
49LithiumLithium (Li) has atomic number 3 on the IUPAC periodic table.Aliases: Li
48NeonNeon (Ne) has atomic number 10 on the IUPAC periodic table.Aliases: Ne
47SodiumSodium (Na) has atomic number 11 on the IUPAC periodic table.Aliases: Na
42CalciumCalcium (Ca) has atomic number 20 on the IUPAC periodic table.Aliases: Ca
39NitrogenNitrogen (N) has atomic number 7 on the IUPAC periodic table.Aliases: N
38AluminiumAluminium (Al) has atomic number 13 on the IUPAC periodic table.Aliases: Al · Aluminum
35HeliumHelium (He) has atomic number 2 on the IUPAC periodic table.Aliases: He
26CopperCopper (Cu) has atomic number 29 on the IUPAC periodic table.Aliases: Cu
25IronIron (Fe) has atomic number 26 on the IUPAC periodic table.Aliases: Fe
20CarbonCarbon (C) has atomic number 6 on the IUPAC periodic table.Aliases: C
18HydrogenHydrogen (H) has atomic number 1 on the IUPAC periodic table.Aliases: H
15OxygenOxygen (O) has atomic number 8 on the IUPAC periodic table.Aliases: O
12Why these answers qualify
Each entry belongs to the bounded set defined by the prompt. The named source supports the underlying facts; our editorial scoring is a separate layer.
Source: IUPAC · Periodic table
Reference version: 2026-09-13. See our answer policy for how we handle aliases and omissions.