The ionic bond consists of the union of ions with charges of opposite signs by electrostatic forces. It occurs with the transfer of electrons from one atom to another, forming cations (positive ions) and anions (negative ions), which attract each other.
This chemical bond, therefore, occurs between elements that have large electronegativity differences, forming ion agglomerates. The greater the electronegativity difference between these elements, the greater the ionic character of the bond.
It occurs between: metal + nonmetal and metal +
- 1 Features
- 2 Formation of ionic compounds
- 3 Examples
- 4 More examples
Features of ionic compounds :
Ionic compounds have a crystalline structure regardless of their nature. This fact gives all of them characteristic properties, among which are:
- At room temperature they are solid . The forces of attraction are so strong that in the crystalline network the ions continue to occupy their positions, even at hundreds of degrees Celsius of temperature. Therefore, they are hard and melt at high temperatures.
- They do not conduct current when they are in a solid state , but they are conductive when they dissolve or melt. By introducing two electrodes, one positive and the other negative, in an ionic solution, a flow of electric charges or ions is created: the anions are attracted by the anode and repelled by the cathode and the cations are attracted by the cathode and repelled by the anode. This phenomenon is called ionic conductivity.
- They have high boiling and melting temperatures due to the strong attraction between ions. Therefore, they can be used as refractory material.
- They are hard and fragile . Hardness, which is understood as scratch resistance, is considerable in ionic compounds; This resistance is explained by the difficulty that a crystalline structure has of breaking (highly stable) through a mechanical procedure.
- They have a lot of resistance to dilation . The increase in volume means a weakening of the forces of ionic attraction.
- They are generally soluble in water . The solutions obtained are good conductors of electricity (electrolytic).
Formation of ionic compounds
Ionic bonds occur, as a general rule, between the elements that tend to lose electrons (low electronegativity), which have 1, 2 or 3 electrons in the last layer (metals), and the elements that tend to gain electrons (high electronegativity ), which have 5, 6 or 7 electrons in the last layer (not metals).
Metal ⇒ less than 4 electrons in the last layer. electrons; they become cations (positive ions).
Non-mental ⇒ more than 4 electrons in the last layer. They receive electrons; they become anions (negative ions).
After the transfer of electrons from metal to nonmetal, there is a strong electrostatic attraction between the ions of opposite charges (ionic bond).
Note: Ionic compounds (compounds that have ionic bonding) are electrically neutral, that is, the total sum of the positive charges is equal to the total sum of the negative charges.
NaCl (sodium chloride): the table salt used to flavor foods.
MgCl2 (magnesium chloride): salt used for culinary, therapeutic and even industrial purposes.
KBr (potassium bromide): provides ions that are important for the manufacture of photographic films.
CaCO3 (calcium carbonate): it is used in the production of glass and in reactions to make soap and detergent.
Na2SO4 (sodium sulfate): can be used in various industrial processes, such as in the production of dyes for fabrics; It is also used in medicine as a laxative.
- Manganese Chloride (MnCl2)
- Potassium Sulfate (K2SO4)
- Sodium Hypochlorite (NaClO)
- Iron sulfide (Fe2S3)
- Disodium Phosphate (Na2HPO4)
- Potassium Dichromate (K2Cr2O7)
- Calcium phosphate (Ca3 (PO4) 2)
- Calcium nitrate (Ca (NO3) 2)
- Potassium Hydroxide (KOH)
- Lithium Fluoride (LiF)
- Silver Nitrate (AgNO3)
- Zinc Hydroxide (Zn (OH) 2)
- Potassium iodide (KI)
- Copper Sulfate (CuSO4)
- Magnesium Oxide (MgO)