Rubidium

Definition

Rubidium is a soft, silvery-white alkali metal that is the second most electropositive and reactive of the stable elements. It is commonly found in the Earth's crust and has various applications in electronics and nuclear technology.

5 Must Know Facts For Your Next Test

1. Rubidium is the fifth most abundant element in the Earth's crust, behind oxygen, silicon, aluminum, and iron.
2. Rubidium has a low ionization energy, making it highly reactive and readily forms positive ions when it loses its valence electron.
3. The reactivity of rubidium increases as you move down the alkali metal group, with rubidium being more reactive than the earlier alkali metals.
4. Rubidium has a low melting point of 39.3°C, making it one of the most reactive solid elements at room temperature.
5. Rubidium is used in photocells, optical glasses, and specialized electronics due to its unique optical and electrical properties.

Review Questions

• Explain how the position of rubidium in the periodic table relates to its reactivity.
  • Rubidium is an alkali metal located in group 1 (the alkali metal group) of the periodic table. As you move down the group, the alkali metals become increasingly reactive due to their low ionization energies and the ease with which they lose their valence electrons to form positive ions. Rubidium, being the fifth element in the group, is more reactive than the earlier alkali metals like lithium and sodium. This high reactivity is a defining characteristic of rubidium and a key reason for its various applications in electronics and nuclear technology.
• Describe the role of electronegativity in understanding the properties of rubidium.
  • Electronegativity is a measure of an atom's ability to attract shared electrons in a chemical bond. Alkali metals, including rubidium, have very low electronegativities, meaning they readily lose their valence electrons to form positive ions. This low electronegativity is a result of rubidium's large atomic size and the relatively weak nuclear charge holding its valence electrons. The low electronegativity of rubidium contributes to its high reactivity and the ease with which it can participate in chemical reactions, a key aspect of the periodic trends observed for the alkali metals.
• Evaluate how the unique properties of rubidium, such as its low melting point and high reactivity, influence its practical applications.
  • Rubidium's low melting point of 39.3°C, combined with its high reactivity, makes it a valuable element in specialized electronic and optical applications. The low melting point allows rubidium to be used in photocells, where its photoelectric effect can be leveraged. Additionally, rubidium's reactivity enables its use in certain nuclear technologies, such as in the construction of atomic clocks, where its stable isotopes can provide highly accurate time-keeping capabilities. These practical applications highlight how the periodic trends and unique properties of rubidium, rooted in its position in the periodic table, contribute to its versatility and usefulness in various industries.

Related terms

Alkali Metals:

A group of highly reactive elements in the periodic table, including lithium, sodium, potassium, rubidium, cesium, and francium.

Electronegativity:

A measure of an atom's ability to attract shared electrons in a chemical bond.

Periodic Trends:

The patterns and changes observed in the properties of elements as you move across a period or down a group in the periodic table.