Alkali Metals

Definition

Alkali metals are a group of highly reactive metals found in Group 1 of the periodic table, including lithium, sodium, potassium, rubidium, cesium, and francium. These elements share similar properties, such as low melting and boiling points, low density, and the tendency to lose one electron to form cations with a +1 charge. Their reactivity increases as you move down the group, making them significant in various chemical reactions and applications.

5 Must Know Facts For Your Next Test

1. Alkali metals are stored under oil or in inert gases to prevent reactions with moisture and oxygen in the air.
2. They have low densities compared to other metals, with lithium being less dense than water.
3. Alkali metals react vigorously with water to produce hydrogen gas and a strong alkaline solution, exemplifying their reactivity.
4. The trend of reactivity among alkali metals increases down the group, with francium being the most reactive.
5. Due to their high reactivity, alkali metals are not found freely in nature but rather in compound forms.

Review Questions

• How does the reactivity of alkali metals change as you move down the group in the periodic table?
  • As you move down the alkali metal group in the periodic table, the reactivity increases. This is because the outermost electron becomes further away from the nucleus due to increasing atomic size, making it easier for the atom to lose that electron. For instance, while lithium reacts moderately with water, cesium reacts explosively. This trend is a key characteristic of alkali metals.
• Discuss the significance of alkali metals in chemical reactions and how their properties affect their applications.
  • Alkali metals are significant in chemical reactions due to their high reactivity, which allows them to easily form compounds. Their tendency to lose one electron makes them valuable in producing strong bases when they react with water. For example, sodium hydroxide, produced from sodium reacting with water, is widely used in industries. The unique properties of alkali metals make them essential for various applications in chemistry and manufacturing.
• Evaluate how the properties of alkali metals influence their behavior in different environments and their industrial uses.
  • The properties of alkali metals significantly influence their behavior in different environments. Their high reactivity necessitates storage under oil to prevent unwanted reactions with air and moisture. This reactivity also dictates their industrial uses; for instance, sodium is used in vapor lamps and lithium is essential in batteries. Understanding these properties helps predict how alkali metals will interact with other substances and informs safe handling practices.

Related terms

Ionization Energy:

The energy required to remove an electron from an atom or ion, which decreases down the group for alkali metals due to increased atomic size.

Electronegativity:

A measure of an atom's ability to attract and hold onto electrons; alkali metals have low electronegativity values.

Alkaline Earth Metals: The elements in Group 2 of the periodic table that are also metals but are less reactive than alkali metals.