These 3 definitions for a base are as follows:. Arrhenius Concept : Any compound which furnishes OH - ions in its aqueous solution is termed as a base. This is a simplest definition of a base. In general bases are the compounds that react with acids to produce salt.
This definition covers some of the bases but leaves out many. So, other definitions of bases were given by different scientists. Bronsted Lowry Concept : Any compound that is capable of accepting a proton i. By this definition, even H 2 O can act as a base as it can acquire a proton to form hydronium ion i. So, another definition of a base was given by Lewis.
Lewis Concept : Any compound that can donate a lone pair or can donate a pair of electrons is termed as a base. For instance: NH 3 is a Lewis base. It has a lone pair which it can donate. So, according to this definition any compound, ion or element which can donate a pair of electrons to the other species can act as a base.
It can be CuO, ZnO. It is a more generalized definition. Therefore, Lewis concept covers most of the aspects of a base. The emission of this electron is easy; thus, alkali metals are very reactive.
Further, the reactivity increases down the group 1 of the periodic table. These metals form ionic compounds with other electronegative atoms. More accurately, the term alkali refers to the carbonate or the hydroxide of an alkali metal. They also have basic properties. They are bitter in taste, slippery, and react with acids, to neutralize them. Arrhenius defines it as a substance that donates OH- ions to the solution.
Bronsted- Lowry defines a base as a substance that can accept a proton. According to Lewis, any electron donor is a base. According to the Arrhenius definition, a compound should have a hydroxide anion and the ability to donate it as a hydroxide ion to be a base. For instance, NH 3 is a Lewis base, because it can donate the electron pair on nitrogen. Bases have a slippery soap like feeling and a bitter taste. They react easily with acids producing water and salt molecules. Caustic soda, ammonia, and baking soda are some of the common bases.
We can categorize these compounds into two groups, depending on their ability to dissociate and produce hydroxide ions. In essence, all alkalis are bases but not the other way. When an alkali is added to any other acid the PH increases. In contrast, when an acid is added to an alkali the PH decreases due to the removal of alkali. The difference between alkali and base is that alkali dissolves in the water fast. Bases, on the other hand, do not dissolve in water. Alkali metals are soft, shiny, and not very heavy.
They have a weak metallic bond and that is why they are soft. They can easily be sliced into two using a knife. A base is a substance used to neutralize acids. Metal oxides and metal hydroxides are examples of bases that form neutral products with acids. Bases are slippery and bitter when you taste. They produce molecules and water when they react with acids. Alkalis are chemical compounds. They contain one electron in their outermost layer of electrons. To get rid of the outermost electron from an alkali metal require less energy.
Ionization energy is the energy required to remove an electron from the outer shell of alkali. They are soft metals as a result of the metallic bonding. As such, you can cut them using a knife. Still, they have low boiling and melting points. Alkalis are reactive metals. They are kept in solutions such as kerosene to prevent them from reacting with the atmosphere.
When burning with oxygen, they form colored flames. The density of alkali metals is lower compared to other metals. And they are good conductors of heat and electricity. A base is a substance that is used to neutralize the acid.
They may or may not be soluble in water. Those that dissolve in water are known as alkalis. Bases are bitter to taste and this is a feature of all bases.
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