[Li] Lithium (least reactive alkali metal)
- A soft, silvery metal. It has the lowest density of all metals. It reacts vigorously with water
An example of a reaction between lithium and chlorine
Lithium has a melting point of 181 degreesC
lithium + chlorine → lithium chloride
2Li(s) + Cl2(g) → 2LiCl(s)
- Sodium is a soft metal that tarnishes within seconds of being exposed to the air. It also reacts vigorously with water.
Sodium reacts with Chlorine to form NaCl (table salt)
Sodium and the other alkali metals are so reactive that they're never found alone in nature. They're always bonded with at least one other element to form compounds.
- A soft, silvery metal that tarnishes in air within minutes.
Potassium is essential to life. Potassium ions are found in all cells. It is important for maintaining fluid and electrolyte balance.
Pure potassium is a highly reactive metal. Exposed to water, it explodes with a purple flame, so it's usually stored under mineral oil for safety.
Because it's so reactive, potassium isn't found free in nature
Rubidium is a silvery-white and very soft metal — and one of the most highly reactive elements on the periodic table.
Rubidium has a density about one and a half times that of water and is solid at room temperature.
Rubidium reacts violently with water, oxidizes when reacting with oxygen, and ignites due to humidity in the air, so great care must be taken when working with the element.
Scientists treat rubidium as a toxic element.
- Caesium is a rare, silver-white, shiny metal with brilliant blue spectral lines.
It is the softest metal, with a consistency of wax at room temperature. It would melt in your hands — if it didn't explode first, as it is highly reactive to moisture.
Cesium is a naturally occurring element, although almost never on its own.
- Francium is extremely rare. Because of this its chemical and physical properties are not known.
- It has been studied by radiochemical techniques, which show that its most stable state is the ion Fr+.
- Francium is the least electronegative of all the known elements.
No use has been found for what little francium can be produced.
Francium occurs naturally to a very limited extent in uranium minerals.
Nevertheless it has been estimated that there might be from 340 to 550 grams of francium in the earth's crust at any one time.
Francium is the second rarest element in the crust, after astatine.
Written by Bryant Wong (Chemistry)