Z=11 vs Z=19
Place two elements side by side. Start from atomic number and position, then read the differences in the context of periodic trends rather than as isolated facts.
Z=11
Z=11
Obre l’element →Z=19
Z=19
Obre l’element →Mendeleev
Do not compare numbers without asking why they differ. Are the atoms in the same group? The same period? Has a new electron shell appeared? That is where the periodic table becomes an explanation rather than a list.