37. Rubidium

Name: Rubidium
Symbol: Rb
Atomic Number: 37
Atomic Mass: 85.4678 amu
Melting Point: 38.89 °C (312.04 °K, 102.002 °F)
Boiling Point: 688.0 °C (961.15 °K, 1270.4 °F)
Number of Protons/Electrons: 37
Number of Neutrons: 48
Classification: Alkali Metal
Crystal Structure: Cubic
Density(293 K): 1.532 g/cm3
Color: silver

Rubidium can be liquid at ambient temperature, but only on a hot day given that its melting point is about 40°C. It is a soft, silvery-white metallic element of the alkali metals group (Group 1). It is one of the most most electropositive and alkaline elements. It ignites spontaneously in air and reacts violently with water, setting fire to the liberated hydrogen. As so with all the other alkali metals, it forms amalgams with mercury. It alloys with gold, caesium, sodium, and potassium. It colours a flame yellowish-violet.

Rubidium (Latin rubidus, meaning deepest red) was discovered in 1861 by Robert Bunsen and Gustav Kirchhoff in the mineral lepidolite through the use of a spectroscope. However this element had minimal industrial use until the 1920s. Historically, the most important use for rubidium has been in research and development, primarily in chemical and electronic applications.

Rubidium reacts violently with water and can cause fires. To ensure both safety and purity, this element must be kept under a dry mineral oil, in a vacuum or in an inert atmosphere.

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Non-metals H, C, N, O, P, S, Se
Halogens F, Cl, Br, I, At
Alkali metals Li, Na, K, Rb, Cs, Fr
Alkaline Earth Be, Mg, Ca, Sr, Ba, Ra
Transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Uub
Metalloids B, Si, Ge, As, Sb, Te, Po
Other metals Al, Ga, In, Sn, Tl, Pb, Bi
Rare Earth Lu, Lr, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No
Noble gases He, Ne, Ar, Kr, Xe, Rn

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