What is the heaviest alkali metal?

The heaviest alkali metal is francium (Fr), with an atomic number of 87. Francium is an extremely rare and highly unstable element, making it difficult to study and obtain significant amounts of it. It is a member of the alkali metal group, located in the first column of the periodic table.

Due to its high reactivity and radioactivity, francium is not found naturally on Earth and only trace amounts have been produced in laboratories. It is usually produced artificially through the decay of other radioactive elements, such as actinium or radium. Its short half-life of about 22 minutes further adds to the challenges of studying and observing its properties.

Being an alkali metal, francium shares similar characteristics with its lighter siblings: lithium, sodium, potassium, rubidium, and cesium. It has a single valence electron in its outermost energy level, giving it strong metallic properties such as high electrical and thermal conductivity. Like other alkali metals, it is highly reactive and reacts vigorously with water and oxygen.

Due to its scarcity and limited knowledge about its chemical properties, there are no known practical applications for francium. However, its radioisotopes have been used in scientific research, particularly in investigations related to nuclear structure and fundamental forces in physics.