Elements 21–30 on the periodic table

Follow protons, not atomic weights

Each step adds one to the atomic number: scandium is 21, titanium 22 and vanadium 23, continuing through zinc at 30. An isotope can have a different number of neutrons while remaining the same element. Consequently, isotope masses and the rounded atomic weights printed on classroom tables cannot be used as the sorting key. The numerical table here supplies the exact quantity that defines each element, without mixing it with a measured average mass.

The cobalt–nickel trap

Cobalt precedes nickel because their atomic numbers are 27 and 28. Their standard atomic weights do not increase in that same order. This is a concrete example of why a memorised “lighter to heavier” rule can fail even within ten adjacent elements. If two references appear to disagree, first check whether one has been sorted by atomic weight. The periodic table’s modern ordering is by atomic number, which stays fixed across different samples and isotopic compositions.

Why some symbols seem unrelated to English names

Iron’s Fe and copper’s Cu are rooted in older names rather than the first letters of their modern English names. The game’s name directory accepts the associated element symbols as aliases, but the answer rows use full names. Chromium, manganese and magnesium are also easy to confuse: magnesium is number 12 and lies outside this range. Similar spelling does not imply adjacent positions, and a familiar two-letter symbol is often a better memory cue than a partial name.

A block is not a universal chemical category

These entries occupy the first d-block row, but the definition of a transition element is more specific than simply appearing in that block. Zinc’s filled d shell makes it an instructive boundary case. This puzzle avoids that classification dispute by stating atomic numbers directly. The same distinction matters in other science rankings: a precisely defined numerical interval can have an unambiguous answer set even when the broader category name has exceptions or competing classroom conventions.

Sources & further reading

• IUPAC — Periodic Table
• Royal Society of Chemistry: periodic table

Explanation updated Sunday, November 1, 2026. The puzzle’s original data date is listed below.