Group 2 Property Trends

Element	Config	$IE_{1}$ (kJ/mol)	$IE_{2}$ (kJ/mol)	Ionic radius $M^{2+}$ (pm)	Flame Color
Be	[He]2 $s^{2}$	899	1757	27	— (no characteristic flame)
Mg	[Ne]3 $s^{2}$	738	1451	72	No distinct flame (UV emission)
Ca	[Ar]4 $s^{2}$	590	1145	100	Brick red / orange-red
Sr	[Kr]5 $s^{2}$	549	1064	118	Crimson red
Ba	[Xe]6 $s^{2}$	503	965	135	Apple green

Compound Type	Trend Down Group 2	Key Examples
Sulphates ( $SO_{4}^{2-}$ )	↓ Decreases ( $BeSO_{4}$ most soluble; $BaSO_{4}$ insoluble)	$BaSO_{4}$ used as barium meal (X-ray)
Hydroxides ( $OH^{-}$ )	↑ Increases (Be(OH){2} barely soluble; Ba(OH){2} strongly soluble)	Ba(OH)_{2} used in titrimetry
Carbonates ( $CO_{3}^{2-}$ )	↓ Decreases ( $BeCO_{3}$ most soluble; $BaCO_{3}$ least soluble)	All are sparingly soluble
Nitrates	All soluble	—

Memory trick: "Sulphate decreases ↓, Hydroxide increases ↑ going down Group 2."