An alkali metal is an element present in group 1A of the periodic table defined by their reactivity and having one valence electron.
The alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). Alkali metals are very reactive which is why they are very rarely found by themselves as a single element. They form strong bases with water capable of neutralizing acids. Alkali metals have high thermal and electrical conductivity. They have one valence electron in its outermost shell. They are most commonly found with an oxidation state of +1. They also have low ionization energy, low electron affinity, and low electronegativity. Alkali metals easily lose one electron to form univalent cations and react readily with nonmetals and all have 1 electron in the s subshell having the common electronic structure Xs1, where X is the period the element is in.
Key Points
• Alkali metals have a single valence electron
• They have low ionization energy, low electron affinity, and low electronegativity
• They want to lose an electron to achieve empty valence shell
• Highly reactive
• Most commonly have an oxidation state of +1
Key Terms
valence electron: an outer shell electron that can participate in chemical bonds
ionization energy: the energy required to remove an electron from the valence shell of a gaseous atom
electron affinity: the energy change that occurs when an atom gains an electron
electronegativity: a measure of the ability of an atom to attract the electrons in a bond
oxidation state: a number assigned to an element in chemical combination which represents the number of electrons lost
univalent: having one valence electron
electronic structure: the descriptive numerical assignments to electrons in different energy levels and spin states in an atom