What is the Difference Between Alkali and Alkaline?

The terms "alkali" and "alkaline" are often used to describe substances with a high pH level (greater than 7), making them basic rather than acidic. However, there are some differences between the two terms:

1. Alkali:

• Refers to a base dissolved in a solvent, usually water.
• Acts as a noun, indicating a specific substance.
• Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

1. Alkaline:

• Refers to the adjective form of a substance with a high pH level.
• Can be used interchangeably with the term "base".

In a non-scientific context, the terms "alkali" and "alkaline" can be used to describe the same thing, as they both refer to substances with a high pH level. However, when discussing the terms in a chemical context, there is a difference:

• Alkali:
• Refers to any of the elements in the first group of the Periodic Table, such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
• These elements have one free electron in their outermost shell, making them highly reactive.
• Alkaline Earth Metals:
• Refers to any of the elements in the second group of the Periodic Table, such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
• These elements have two electrons in their outermost shell, making them less reactive than alkali metals.

In summary:

• Alkali: A base dissolved in a solvent, usually water, and refers specifically to the elements in the first group of the Periodic Table.
• Alkaline: An adjective used to describe substances with a high pH level or a base.

Comparative Table: Alkali vs Alkaline

The difference between alkali and alkaline lies in the elements they represent and their properties. Here is a table comparing the two:

In summary, alkali metals are highly reactive and have one valence electron, while alkaline earth metals are less reactive and have two valence electrons. Alkali metals are softer and have lower melting points than alkaline earth metals, and they form +1 cations, while alkaline earth metals form +2 cations.