The substance which produces hydroxide ions when dissolved in water is called Alkalis. Alkali is a base, however not all the bases are Alkalis. So, a basic hydroxide soluble in water would be identified as an Alkali.
These bases are very strong in nature and they can turn a red litmus paper into blue. They usually serve the purpose of neutralizing acids. An Alkali gets its alkaline properties due to Hydroxide ions OH-(aq). We would come across two kinds of Alkali: Alkaline Earth Metals and Alkali Metals.
ALKALI METAL
When the element is one of the following six elements of periodic table Group 1, then they are called Alkali Metals. Those six elements are Lithium (L), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr).
These metals have the electronic configuration of noble gases and are positively charged. And this is done when these metals donate their single outermost electron to the other electron accepting atom. Alkali Metals have special characteristics such as, these are soft in touch because they have low densities. They are also the most reactive metals on the periodic table
ALKALINE EARTH METALS
When the element belongs to one of these six elements of Group 2 of periodic table, then they are called Alkaline Earth Metals. Those six elements are Beryllium (Br), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba) and Radium (Ra).
Alkaline Earth Metals gain their stability by donating their outermost single electron to an electronegative atom. Alkaline Earth Metals are highly reactive and their place as mentioned above is found in the second group of periodic table. Alkaline Earth metals can be found in everything, as the world is quite literally made of them.
An interesting fact about Alkaline Earth metals is that before the 19th century, any substance which was nonmetallic in nature and also insoluble in water and immune to fire were called Earths. An example pf Earths would be Calcium Oxide otherwise known as Lime. Those Earths which shared some resemblance with Alkaline were considered Alkaline Earths.
This shows that a distinction between Alkaline Earth and Alkaline Metals was still present back then. Only in the early 1800, they discovered that what was considered as elements i.e. Earths, were in fact oxides. They were compounds of metal and oxygen. So, the metals whose oxides made the Alkaline Earth were later recognized as Alkaline Earth metals.
DIFFERENCE BETWEEN ALKALI METALS AND ALKALI EARTH METALS
| ALKALI METALS ALKALI EARTH METALS These metals are soft in touch Alkaline Earth Metals when touched are felt to be hard Alkali Metals consists of 1 electron Alkaline Earth Metals have 2 electrons The melting points of Alkali Metals is low Alkaline Earth Metal’s Melting points are relatively higher Hydroxides are strongly Basic in Alkali Metals Hydroxides are comparatively less basic in Alkaline Earth Metals In case of Alkali Metals, Carbonates do not decompose. In case of Alkaline earth Metals, Carbonates do decompose when exposed to the heating with high temperatures In case of Alkali Metals, Nitrates provide corresponding nitrates and oxygen as products In case of Alkaline Earth Metals, it gives oxides, nitrogen dioxide and oxygen as products In Alkali Metals, Bicarbonates exist in Solid form at room temperature In Alkaline Earth Metals, bicarbonates exist in solution form at room temperature Lithium (L), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr) will be the examples of Alkali Metals. Beryllium (Br), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba) and Radium (Ra) will be the examples of Alkaline Earth Metals. |
PROPERTIES OF ALKALI
Here I would like to discuss the general properties of Alkalis. You will find some Alkalis which will be corrosive in nature, an example of this would be NaOH and KOH. When put to a taste test, you will find that Alkalis are bitter in taste.
Their texture gives off this soapy and slippery feel. When talking about the pH scale any number above the 7 will indicate a stronger Alkali. When Alkali reacts with an acid it performs the process of neutralization which provides one with salt (NaCl) and Water (H2O).
Alkalis are capable of conducting electricity, and the credit for that goes to the mobile ions. For the identification of it on a universal indicator the color will change to either blue or purple. And on a litmus paper, it will turn it from red to blue. Alkalis as obvious by now are highly soluble in water.
USES OF ALKALI
Here I would mention some of the common uses of Alkalis.
Alkali which is also known as sodium hydroxide is commercially used in the manufacturing of soap, paper and detergents. It also serves an interesting purpose which is that in order to make soils or lakes less acidic, slaked lime which is calcium hydroxide it is added to it for the job. You can also find alkalis such as calcium carbonate in building materials.
Alkali also serves a purpose in the farming world which is to make acidic soil more alkaline, for that use the potassium hydroxide is chosen which helps the plants to grow more conveniently.
In human anatomy we can find the problem of indigestion which can be the direct result of excessiveness of HCl in our stomach, the common cure for that is using medicine which contains calcium carbonate or magnesium hydroxide which serves the purpose of neutralizing the acid.
A bee sting, a commonly occurring incident in country sides, can also be fixed by weak alkalis such as ammonia solution because bee sting is acidic in nature. Alkali also serves various purposes in the production of many chemicals.
HAZARDS
As discussed above, Alkalis are very reactive and a reaction such as the production of flammable hydrogen gas which can catch fire at any moment must be expected when alkali metals react with water.
Alkali metals may also produce hazardous substances such as caustic hydroxide solution an example would be Sodium hydroxide, when it comes in contact with water it can become extremely dangerous if bare contact of any kind is made to it. If it inhaled or splashes on skin or even worse digested, it may cause harm.
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