Element 37
Rubidium
Alkali metals
Rubidium (Rb) is in the s-block of the periodic table — group 1, period 5.
Rubidium is a chemical element with symbol Rb and atomic number 37.
Key data
- Atomic number
- 37
- Atomic mass
- 85.468 u
- Group / Period
- 1 / 5
- Block
- s-block
- Phase at STP
- Solid
- Density
- 1.532 g/cm³
- Melting point
- 39.3 °C
- Boiling point
- 687.9 °C
- Electron configuration
- [Kr] 5s1
Periodic table block
Rubidium is in the s-block (group 1, period 5). Elements land in the s-block when their highest-energy electrons fill an s subshell — this includes hydrogen, helium, and the reactive metals on the far left of the table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Atomic clocks
- •Specialty glass
- •Photocells
Discovery
Year: 1861
Discovered by: Robert Bunsen
Frequently asked questions
What is the atomic number of Rubidium?
Rubidium has atomic number 37. Its symbol is Rb and its atomic mass is 85.468 u.
What category of element is Rubidium?
Rubidium is classified as alkali metals. It sits in group 1, period 5 of the periodic table.
What block of the periodic table is Rubidium in?
Rubidium is in the s-block (group 1, period 5). Its highest-energy electrons occupy the s subshell — you can see this in its electron configuration, [Kr] 5s1.
What is Rubidium used for?
Common uses of Rubidium include: Atomic clocks, Specialty glass, Photocells.
When was Rubidium discovered?
Rubidium was discovered in 1861 by Robert Bunsen.
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