Elements And Atomic Number

                          Many different types of atoms are called elements. Each element has a unique set of physical and chemical properties. Elements are a type of matter that can not be broken down into a simpler substance by chemical reaction. Some familiar elements are oxygen, carbon, sodium, gold, and hydrogen.

                          Elements are identified by the number of protons in their nucleus, known as the atomic number ( Z ). An element's atomic number ( Z ) also indicates the same number of electrons in the neutral atom.

For Example :

Hydrogen                                                                    Helium

Z = 1                                                                           Z = 2

Proton - 1                                                                    Proton - 2

Electron - 1                                                                 Electron - 2

(Remember atoms have an equal number of protons and electrons.)

                All elements are organized according to their atomic number in the periodic table. In the periodic table, the order of an element's atomic number increases from left to right and top to bottom. Elements are further organized as columns based on their properties. Elements in the same column have similar physical and chemical properties. Many elements are represented by their English names and chemical symbols.

Example:

Hydrogen - H

Helium - He

            Some elements are represented by their Latin names and chemical symbols. 

Example:

Mercury - chemical symbol Hg. It comes from the Latin name of Hydrargyrum.

Lead - chemical symbol Pb. It comes from the Latin name of Plumbum.

                In the periodic table, the boxes of each element will always contain atomic number, chemical symbol, name, and atomic mass.

Explanation:

                 At the top of the box Hydrogen atomic number is 1. Below that Hydrogen chemical symbol H followed by its name Hydrogen. The bottom number is the Atomic mass. Hydrogen atomic mass 1.008

Atomic Structure ( Atoms )

 Atomic Structure:

       The arrangements of protons, neutrons, and electrons within an atom.

What are atoms?

    Atoms are basic units of matter and building blocks of everything in the universe. They maintain all the properties of chemical elements. Atoms comprise smaller subatomic particles called protons, neutrons, and electrons.

Structure of atoms:

            outside the nucleus, we have electron clouds. The dense region at the center of an atom is the nucleus. It's made up of protons and neutrons. Neutrons have no charge ( neutral ). Protons are positively charged (1+). Electrons are negatively charged ( 1- ).

       The unit we used to express the masses of subatomic particles is the abbreviation of unified atomic mass unit ( u ) AMU. Protons and neutrons have similar mass unit 1u. All the mass of an atom is the nucleus not in the electron cloud.

Properties Of Boric Acid

                Boric acid reacts with sodium hydroxide to form sodium metaborate and sodium tetraborate. 

                   H₃BO₃  +  NaOH  ———>  NaBO₂  +  2H₂O

                  4H₃BO₃  +  2NaOH  ———>  Na₂B₄O₇  +  7H₂0

Action Of Heat:

              Boric acid heated above 170 degree Celsius to gives metaboric acid.

                                 4H₃BO₃  ———>  4HBO₂  +  H₂0

              Boric acid heated above 300 degree Celsius to gives tetraboric acid.

                               4HBO₂   ———>  H₂B₄O₇  +  H₂O

             Tetraboric acid heated above 330 degree celsius to gives boron trioxide.

                               H₂B₄O₇  ———>  2B₂O₃  +  H₂O

Action Of Ethyl Alcohol:

              Boric acid reacts with ethyl alcohol in the presence of concentrated sulphuric acid to form triethylborate. The ethyl borate burns with green edged flame.

                              4H₃BO₃  +  3C2H5OH   ———>   B(OC2H5)3  +  3H2O

Action Of Calcium Fluoride:

            Boric acid reacts with calcium fluoride in the presence of concentrated sulphuric acid to gives boron trifluoride.

                            2H3BO3  +  3CaF₂  +  3H₂SO₄   ———>  2BF₃  +  3CaSO₄  +  6H₂O

Preparation Of Boric Acid

 Boric Acid:

             A mixture of concentrated sulphuric acid reacts with borax to form boric acid.

Na₂B₄O₇  +  H₂SO₄  +  5H₂O ———>      Na₂So₄          +          4H₃BO₃

                                                          ( Sodium sulfate )        ( Boric acid ) 

Boric acid can be extracted from colemanite. 

Ca₂B₆O₁₁  +  11H₂O₄  +  SO₂  ———>  Ca(HSO₃)₂  +  6H₃BO₃

Uses Of Boric Acid

• Boric acid is used in the manufacture of pottery glaze glass, enamels and pigments.
• Boric acid is used as an antiseptic, insecticide and flame retardants.
• Boric acid is used as a food preservatives.
• Boric acid is used in the production of LCD flat panel display.
• Boric acid is used to prevent existing wet and rot in timber etc....

Uses Of Borax

 Borax Uses:

• Borax is used fir the identification of colored metal ions.
• Peroxoborate present in washing powder. It's a cleaning and bleaching agent.
• Borax is a flux for soldering. And also acts as a good preservative.
• In the manufacture optical and borosilicate glass, enamels and glazes for pottery.
• Borax is used as fungicide, fire retardant and in softening water.
• Borax is used for stiffening agent for candle wicks. 
• Borax is used as antiseptic soaps.

Properties Of Borax

Properties Of Borax:

• Borax is a white crystalline solid, less soluble in water but more soluble in hot water.
• Borax dissolved in hot water to gives the alkaline solution of boric acid and sodium hydroxide.

                    Na₂B₄O₇  +  7H₂O  ———>  4H₃BO₃  +  2NaOH

• On heating, borax loses its water of crystallization and swells up to form a puff mass. On further heating, it melts into a clear liquid which solidified to a transparent glass like bead. Which consist of sodium metaborate and boric anhydride. This glass bead is commonly called as borax bead.                                                                                

                     Na₂B₄O₇.10H₂0 ———> Na₂B₄O₇ ———> 2Na₂BO₂ + B₂O₃

• Borax beads are used in laboratory to identify some metals in salts, through borax beads test. Nickel salts give brown colored bead. Cobalt slats give blue colored bead. White chromium salt gives green bead in flame.
• Borax reacts with acids like sulphuric acid and hydrochloric acid to form sparingly soluble boric acid.

                              Na₂B₄O₇ + 2HCl + 7H₂O  ———> 4H₃BO₃  +  2NaCl

                              Na₂B₄O₇  +  H₂SO₄  +  5H₂O  ———>  4H₃BO₃  +  2Na₂SO₄

• Borax reacts with Ammonium Chloride to form boron nitride.

                              Na₂B₄O₇  +  2NH₄Cl  ———>  2NaCl  +  2BN  +  B₂O₃  +  2H₂O

• Borax heated with ethyl alcohol and concentrated sulphuric acid, to forms vapors of triethylborane. When ignited these vapor burn with green edged flame.

                  Na₂B₄O₇  +  H₂SO₄  +  5H₂O ———> Na₂SO₄  +  4H₃BO₃

                  H₃BO₃  +  3C₂H₅OH  ———>  B(OC₂H₅)₃  +  3H₂O