Monday, August 19, 2019

General properties of p-block elements:

Atomic size:
       In p- block elements atomic size decreases from left to right. When we move down the group atomic size increases.
Example: Boron to Thallium

Ionization energy:
        In p-block elements ionization energy increases from left to right. when we move down the group ionization energy decreases.

Electronegativity:
        In p-block elements electronegativity increases from left to right. When we move down the group electronegativity decreases.

Electron affinity:
        In p-block elements electron affinity increases from left to right. when we move down the group electron affinity decreases.

Allotropy:
        Allotropy means one element can exist in many forms.

Elements in the p-block of the periodic table:

   Non-metals and metalloids exist only in the p-block of the periodic table.

METALS                     Non-METALS                            METALLOIDS
Aluminium                       Helium                                           Boron
Gallium                            Carbon                                           Silicon
Indium                              Nitrogen                                        Germanium
Thallium                          Oxygen                                          Arsenic
Tin                                   Fluorine                                         Antimony
Lead                                 Neon                                             Tellurium
                                         Phosphorous                                  Polonium
                                         Sulphur                                          Astatine
                                          Chlorine
                                          Argon
                                          Selenium
                                          Bromine
                                          Krypton
                                          Iodine
                                          Xenon
                                          Radon

Friday, May 1, 2015

Solidification

       In solidification reaction substances changes from a liquid to a solid when its temperature is lowered below its freezing point. It is also known as freezing.
Example:
  Water changing to ice.

Wednesday, April 29, 2015

Saponification

               Animal fats and vegetable oils are esters of carboxylic acids. These fats and oils are called triglycerides. Triglycerides reacted with sodium or potassium hydroxide to produce fatty acid salt and glycerol. The salt of fatty acid is called soap.
*Saponification process is a hydrolysis reaction.
*Soap is produced by saponification of a triglyceride.
*Soap is a salt composed of a mixture of carboxylate anion and univalent cations.
*Sodium hydroxide produce hard soap.
*Potassium hydroxide produce soft soap.
*Potassium soaps are more soluble than sodium soaps and readily produce lather.

How Soap Clean ?
       The hydrophilic (carboxylate) end of the soap molecules attached to water. The hydrophobic (hydrocarbon chain ) end attached to oil and grease. The more and more soap molecules embedded
into a grease to forming micelles around oil droplets. The hydrophobic ends of the soap molecules attached towards the grease while the hydrophilic ends of the soap face outward into the water, resulting is an emulsion of soapy grease particles suspended in the water. Then the oily particles are easily washed away. The water agitation can help to clean greasy and oil. The micelles are dispersed into the water.
                                          Hydrophilic -  ( water loving )
                                         Hydrophobic- ( water hating )
              Soap do not work well in hard water. Hard water containing calcium and magnesium ions. these ions react with soap to form an insoluble precipitate known as soap film. This precipitate is often seen as a gray line on a bathtub or sink and is often called scum.

Detergents:
       Detergents are similar to soaps. They work in both soft and hard water. The detergent removes the oil film and the dirt can be washed away.

Tuesday, April 28, 2015

Solidification

          Substance changes from a liquid phase to solid phase when its temperature is lowered below its freezing point. it is also known as freezing.

Saponification

              Triglycerides reacted with sodium or potassium hydroxide to produce fatty acid salt and glycerol.

Rusting of Iron

         Iron combine with oxygen in the presence of water molecule to form a iron oxides. (rust).