Periodic Table
19
K
39.098
Potassium
Alkali MetalViolet/lilac flame; very reactive; vital electrolyte (K⁺).
Electronic Configuration
[Ar] 4s¹or1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Electron shells
2e⁻n=1
8e⁻n=2
8e⁻n=3
1e⁻n=4
Properties
Atomic number
19
Atomic mass
39.098 u
Category
Alkali Metal
Block / Group / Period
s · 1 · 4
Valence electrons
1
Oxidation states
+1
Electronegativity
0.82
Atomic radius
243 pm
Ionization energy
419 kJ/mol
Electron affinity
48 kJ/mol
Melting point
336 K / 63 °C
Boiling point
1032 K / 759 °C
Density
0.862 g/cm³
State at 25 °C
solid
JEE / NEET notes
- Forms superoxide KO₂ on burning (paramagnetic, O₂⁻).
- Flame colour seen through blue glass appears crimson.
Flame test
Lilac / violet
Ores & extraction
Ores: Sylvite (KCl), Carnallite (KCl·MgCl₂·6H₂O)
Uses
Fertilisers (potash) · KO₂ in breathing apparatus · Gunpowder (KNO₃)
Important compounds
KClKOHKNO₃KO₂
Personal Notes
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