Chemical Combinations

 

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In today’s class, we will be talking about chemical combinations. Enjoy the class!

CHEMICAL COMBINATIONS

2019 Definition of Laws Of Chemical Combinations|Dalton's Atomic ...

ELECTROVALENT (IONIC) BOND

Electrovalent bond is characterised by the transfer of electrons from metallic atoms to non-metallic atoms during the reaction. The metallic atom that donates electron becomes positively charged while the non-metallic atom that accepts electron becomes negatively charged. The strong electrostatic attraction that holds the oppositely charged ions together is called an ionic bond.

CHEMICAL COMBINATIONS CHEMISTRY SS1

ELECTRON DOT REPRESENTATION OF FORMATION OF IONIC COMPOUNDS
  • Formation of sodium chloride:

CHEMICAL COMBINATIONS CHEMISTRY SS1 2

  • Formation of calcium oxide:

CHEMICAL COMBINATIONS CHEMISTRY NOTES

PROPERTIES OF SOME IONIC COMPOUNDS
  1. They are solids at room temperature.
  2. They contain oppositely charged ions.
  3. They readily dissolve in water and other polar solvents like ethanol.
  4. They have high melting and boiling points
  5. They are good conductors of electricity when in molten or in aqueous form.

EVALUATION

  1. How is an ionic compound formed?
  2. State the properties of an ionic compound

COVALENT BOND

This involves the sharing of a paired electron between two reacting atoms. The shared electrons are each contributed by the reacting atoms and are called shared pair. A shared pair of an electron in the covalent bond is represented by a horizontal line (—-) between the two atoms

ELECTRON DOT REPRESENTATION OF FORMATION OF COVALENT COMPOUNDS
  • Formation of a hydrogen molecule:

CHEMICAL COMBINATIONS CHEMISTRY SS1 4

  • Formation of carbon (iv) oxide:

CHEMICAL COMBINATIONS CHEMISTRY SS1 5

PROPERTIES OF COVALENT COMPOUNDS
  1. They consist of molecules with a definite shape.
  2. They are gases or volatile liquids.
  3. They readily dissolve in non-polar organic solvents
  4. They have low melting and boiling points
  5. They do not conduct electricity because the molecules do not contain charged particles.

EVALUATION

  1. What is a covalent bond?
  2. Outline the properties of covalent compounds

COORDINATE COVALENT (DATIVE) BOND

In a coordinate covalent bond, the shared pair of electrons are supplied by one of the combining atoms. A coordinate covalent bond is often formed in molecules that have a lone pair of electrons, i.e. a pair of electron not directly concerned in an existing bond.

ELECTRON DOT REPRESENTATION TO SHOW FORMATION OF DATIVE BOND

Formation of hydroxonium ion (H3O+)

Chemical reaction

  • Formation of Ammonium ion (NH4+):

CHEMICAL COMBINATIONS CHEMISTRY SS1 7

Compounds containing coordinate covalent bond are similar in properties to purely covalent compounds. Both do not conduct electricity, but the presence of coordinate covalent bond tends to make a compound less volatile.

 

In our next class, we will be talking about Identification and Types of Alloys.  We hope you enjoyed the class.

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