Characteristics of Covalent Bond

Certain features of covalent bonds are determined by the identities of both the atoms involved in the bond. Bond length & bond polarity are two qualities.

Bond Length

H2 has a specific length (about 7.4 10-11 m). Bond lengths for other covalent bonds are determined by the identities of both the atoms in the bond including whether those bonds are solitary, double, or triple. The actual length of the bond will vary based on the molecule’s identity, but it will be near to the durations of single covalent bonds compared to double and triple bonds even between atoms. The bond length always decreases as the amount of covalent bond atoms rises. The nuclei can move closer together with electrons between them until the internuclear repulsion is strong enough to offset the attraction.

Electronegativity and Bond PolarityThe electrons in a covalent bond are sometimes not shared evenly by the two bound atoms, despite the fact that we characterized covalent bonding as electron sharing. Unless the connection is between two atoms of different elements, as in H2, one atom will always attract the electrons inside the bond greater strongly than the other. An unsaturated covalent bond is one in which the electrons are evenly distributed. A polar covalent bond is one in which the electrons are distributed unequally.In a polar bond, the electron density distribution is uneven. It is the area surrounding the atom which attracts the electrons the most.

The electrons in a hydrogen chloride molecule’s H–Cl bond, for example,spend more time around the chlorine atom than the number of hydrogen atoms.The electron cloud  surrounding Cl is substantially greater than the shaded area around H.

A polar bond is any covalent link connecting atoms of different elements, however the degree of polarity varies greatly. Some interatomic connections are just mildly polar, whereas others are extremely polar. Ionic bonds are the pinnacle of polarity because electrons are passed rather than shared. 

The difference in electronegativities of the individual atoms that make up a covalent bond can be used to determine the polarity of the connection. The bigger the disparity in electronegativities, the more the electron sharing in the bond is unbalanced. Although there are no hard and fast criteria, the general rule is that a bond is nonpolar if the discrepancy in electronegativities is less than around 0.4, and polar if the difference is larger than 0.4. 

Following are  typical characteristics of covalent compounds:

(i) Low melting and boiling points:

Covalent compounds are made up of molecules that are kept together by weak forces. Heat can quickly overcome these obstacles. Covalent compounds contain melting and boiling points as a result. 

(ii) Non-conducting nature:

Molecular compounds don’t really conduct electricity, meaning they do not allow electricity to travel through them. This is due to the lack of ions or free electrons in covalent molecules. Sugar is a covalent molecule that does not conduct electricity in its solution. The presence of ions in polar covalent compound solutions, such as HCl, causes them to conduct electricity. 

(iii) Solubility:

In most cases, covalent compounds are insoluble in polar solvents such as water. Covalent chemicals, on the other hand, dissolve in non-polar solvents such as benzene and toluene. 

(iv) Slow rate of reaction:

Covalent compound reactions are extremely sluggish. Because covalent substances participate in reactions as molecules, and molecular reactions are sluggish, this is the case. 

(v) Isomerism:

Covalent bonds are directed and stiff. As a result, diverse configurations of atoms in space can be obtained. As a result, a single molecular formula can represent a variety of compounds with various properties. 

Properties of Ionic and Covalent Compounds

• Chemical compounds can be classified based on whether they possess ionic or covalent bonding.
•  Ionic compounds, for the most part, have a metal bound to a nonmetal. Ionic chemicals crystallise, have melting and boiling temperatures, are hard and brittle, and act as electrolytes in water.

• Nonmetals linked to one another make up the majority of covalent compounds. Covalent compounds have lower melting and boiling temperatures, are softer, and are electrical insulators than ionic compounds.

Examples of Ionic Compounds

The cation (first part of the formula) of most ionic compounds is metal, while the anion (second part of the formula) is one or more nonmetals. Ionic chemicals include the following:

• Sodium hydroxide (NaOH) 
• Table salt or sodium chloride (NaCl) (NaOH)
• Sodium hypochlorite or chlorine bleach (NaOCl)

Examples of Covalent Compounds

Nonmetals are linked together in covalent compounds. Because the electronegativity values of these atoms are identical or similar, they essentially share electrons. Covalent chemicals include the following:

• Drinking water (H2O)
• Ammonia is a gas (NH3)
• Sucrose (sugar) (C12H22O11)

Conclusion

• The melting and boiling points of most covalent compounds are relatively low.
• Covalent chemicals have lower fusion and vaporisation enthalpies than ionic ones.
• Ionic chemicals are more flammable than covalent ones.
• They do not even conduct electricity when dissolved in water, and they usually respond in molecular form. Covalently bound chemicals make up the majority of the items we consume and use. Plastic, gasoline, and wood, for example. Water is a covalent molecule that serves a variety of functions.