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37 Rb Rubidium 85.46783

Rubidium

ALKALI METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

Rubidium is a chemical element with symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group, with an atomic mass of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, such as very rapid oxidation in air.

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Quick Facts

Atomic Number 37
Period 5
Group 1
Phase Solid
Appearance grey white
About Alkali Metals

Alkali metals are highly reactive, soft, silver, and shiny metals found in Group 1. They readily lose their outermost electron to form positive ions (cations) with a charge of +1.

History

Discovered By Robert Bunsen
Named By Unknown

Physical Properties

Atomic Mass 85.46783
Density 1.532 g/L
Molar Heat 31.06 J/(mol·K)
Phase Transition (Melting & Boiling Points)

Rubidium melts at 312.45 K and boils at 961 K.

Atomic Properties

Electron Config [Kr] 5s1
Electronegativity 0.82
Electron Affinity 46.884 kJ/mol
Ionization Energy 403 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.

Photograph

Image of Rubidium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.