Alkali metals are a group of elements located in group IA in the periodic table, including lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (CS), and francium (FR). These elements share some common characteristics, and their properties are mainly influenced by their valence electron configurations. The atoms of alkali metal elements have one valence electron and they tend to lose this valence electron to form positive monovalent cations. Since this valence electron is the last electron of an alkali metal atom, they are highly active and easily react with other substances. Alkali metal elements have a large atomic radius, which makes their electron cloud susceptible to external influences, further enhancing their activity. The elemental nature of alkali metal elements is a silvery-white metal with low melting and boiling points. As the atomic number increases, the melting and boiling points of alkali metals gradually decrease. For example, lithium has a melting point of 180 degrees Celsius, sodium has a melting point of 98 degrees Celsius, and potassium has a melting point of 63 degrees Celsius. This is because as the atomic number increases, the interaction between the alkali metal atoms gradually weakens, making the lattice structure of the metal more loose. Alkali metal elements are reactive metallic elements that react very violently with oxygen. For example, sodium reacts with oxygen at room temperature to form sodium oxide, sodium peroxide when ignited, and potassium reacts with oxygen to form potassium superoxide when ignited. These reactions are exothermic reactions that can release a large amount of heat energy. The combustion of potassium is more severe than that of sodium, indicating that the chemical properties of potassium are more active than that of sodium.
In addition to the reaction with oxygen, alkali metal elements can also react with other non-metallic elements. For example, they can react with non-metallic elements such as chlorine and sulfur to form corresponding compounds. Most of these compounds are ionic compounds because the alkali metal elements are positive monovalent cations. Alkali metal elements can also react with water to produce corresponding hydrogen and hydroxides. For example, sodium reacts with water to produce hydrogen and sodium hydroxide, which are very violent and can release a lot of heat. For this reason, some substances containing large amounts of alkali metal elements cannot be stored in water to prevent danger. The chemical activity of sodium, potassium and cesium increased sequentially.
The hydroxides of alkali metal elements are strong bases and corrosive. Sodium hydroxide and potassium hydroxide are strong bases commonly used in laboratories to neutralize acidic substances. In addition to common non-metallic elements such as hydrogen, oxygen, nitrogen, chlorine, etc., alkali metal elements can also form compounds with other non-metallic elements. For example, lithium can react with nitrogen to form lithium nitride (Li3N), which is an ionic compound. Lithium can also react with iodine to form lithium iodide (Lii), which is a covalent compound. These compounds all have special properties and uses. Alkali metal elements are a group of elements with unique properties. Their atoms have a valence electron and tend to lose this valence electron to form a positive monovalent cation. This characteristic determines their high activity and the nature of their easy reaction with other substances. With the increase of atomic number, the melting and boiling points of alkali metal elements gradually decrease, and the reactivity gradually increases. These properties make alkali metal elements have a wide range of applications in industry, science and life. For example, in industry, sodium hydroxide and potassium hydroxide are used to make various compounds; In scientific experiments, elements such as lithium, sodium, and potassium are used to study the properties and changes of substances.