Classification of Elements & Periodicity — Visual Overview — Summary

Modern Periodic Table Source: Wikimedia Commons — Modern Long-Form Periodic Table showing all blocks and groups

Core Trend Diagram

Periodic Properties Comparison Table

Property	Direction of Increase	Key Exception	NEET Frequency
Atomic radius	Down group, R→L in period	—	Medium
$IE_{1}$	L→R in period, up group	Be>B; N>O	Very High
EGE	L→R in period, up group	Cl>F (EGE)	Very High
Electronegativity	L→R in period, up group	—	High
Ionic radius (isoelectronic)	Decreasing Z = increasing r	—	Very High
Metallic character	R→L in period, down group	—	Medium

Isoelectronic Series Quick-View

Ion	Protons	Electrons	Radius (pm)
$N^{3-}$	7	10	146 (largest)
$O^{2-}$	8	10	140
$F^{-}$	9	10	133
$Na^{+}$	11	10	98
$Mg^{2+}$	12	10	66
$Al^{3+}$	13	10	51 (smallest)

Pattern: same electron cloud (10 $e^{-}$ ), different nuclear pull. More protons = smaller ion.

Block Summary Diagram (Textual)

The periodic table is a 7-row, 18-column matrix. Columns 1–2 are the s-block (soft metals), columns 13–18 are the p-block (non-metals and noble gases), columns 3–12 are the d-block (transition metals), and the two 14-element rows below the main table are the f-block (rare earth elements). Understanding which block an element belongs to instantly tells you its valence subshell, bonding tendencies, and oxidation state range.