Gym · Periodic trends

Periodic trends: read the table, not the slogan

The periodic table is a database with patterns, and the patterns have exceptions. These drills ask you to compare sourced values — covalent radius, first ionization energy, electronegativity — across periods and down groups, to predict common ions from group position, and to order elements by ionization energy. Every answer is checked against the curated data behind the Valence Table; when the data breaks the naive rule, the explanation names the exception instead of pretending the rule is a law.