Alkali Metals: Elements in Group 1 of the Periodic Table
Alkali metals and alkaline earth metals combine so readily with other elements that they are not found as free elements in nature. In this lesson and the next, you will learn how to identify these metals.
The Alkali Metals
The elements in Group 1 of the periodic table are the alkali metals. Like other metals, Group 1 metals are shiny, malleable, and ductile. They are also good conductors of heat and electricity. However, they are softer than most other metals.
The alkali metals are the most reactive of all the metals. They react rapidly—sometimes violently—with oxygen and water, as shown in the image below. Because they combine so readily with other elements, alkali metals don’t occur in nature in their elemental form and are stored in substances that are unreactive, such as an oil.
Each atom of an alkali metal has one electron in its outer energy level. This electron is given up when an alkali metal combines with another atom. As a result, the alkali metal becomes a positively charged ion in a compound such as sodium chloride, NaCl, or potassium bromide, KBr.
Alkali metals and their compounds have many uses. You and other living things need potassium and sodium compounds to stay healthy. Doctors sometimes use lithium compounds to treat bipolar disorder. The lithium keeps chemical levels that are important to mental health within a narrow range.
A photocell is a solid-state device that converts light into electrical energy by producing a voltage, as in a photovoltaic cell, or uses light to regulate the flow of current, as in a photoconductive cell. The operation of some photocells depends upon rubidium or cesium compounds.
Francium, the last element in Group 1, is extremely rare and radioactive. A radioactive element is one in which the nucleus breaks down and gives off particles and energy. You can find francium in uranium minerals, but only 25 g to 30 g of francium are in all of Earth’s crust at one time.
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