For the alkali metals, amalgamation is exothermic, and distinct chemical forms can be identified, such as KHg and KHg2.[1] KHg is a gold-coloured compound with a melting point of 178 ??C, and KHg2 a silver-coloured compound with a melting point of 278 ??C. These amalgams are very sensitive to air and water, but can be worked with under dry nitrogen.