Melting Point And Polarity: 7 Facts You Should Know


The melting point of a liquid depends upon the type of bonding between the molecules constituting the liquid.

The molecules interact with each other having different electro charges such that the interaction will form two poles of different charges upon the formation of bonds between two oppositely charged ions which is known as polarity, hence the melting point and polarity are related.

Does melting point depend on polarity?

The polarity of the molecules defines the bonding between them and how strong the bond is between the two ions.

The ions are formed as the molecules share the electrons with other elements from the valence shell forming the bonds together, the melting point of the liquids depends upon the polarity of the liquid molecules.

The amount of energy required is based on the number of electrons paired formed with the other molecules, and the charge that the ions carry by sharing electrons that are electro-negative or positive. The greater the electronegative or positive, the stronger will be the bond between the two.

How does melting point depend on polarity?

If the substance is polar then its melting point is higher, depending upon the polarity of the molecules that it is made up of.

The polarity due to the hydrogen bonding is very high and hence accordingly the melting point of the matter goes higher. The polarity of the molecules increases the attraction between the molecules making the bonds very stronger.

A large amount of energy is required to break these bonds. Hence more heat energy is supplied to the matter to enlarge the spacing between the molecules resulting in the melting of the substances.

For example, if we talk about the polarity of water, it is one because water is neutral in charge. But the hydrogen atoms have polarity +1 while the hydrogen elements bond with the oxygen atom making it electronegative with a polarity of -2, as oxygen takes two hydrogen atoms to complete its outer shell.

High melting point is polar or nonpolar?

Nonpolar substances are those which are made up of noble elements or diatomic elements that are found neutral in charge.

The bonds formed by the nonpolar elements are very weak and hence can break easily while the bonds between polar elements are strong and demand enough energy to break these bonds hence the melting point of polar is higher than the nonpolar.

Uridine nucleic acid is a polar component with the chemical formula C4H4N2O2; Image Credit: pixabay

The noble gases element hardly bonds with other elements in nature as its valence shell is completely filled and hence moves freely in the air and is found in inert form. While the diatomic molecules react with the same molecules and become neutral but are not stable and hence break the bonds very easily.

Why do polar molecules have higher melting points?

The polar molecules are the ions formed by donating or accepting the electrons and becoming electropositive or negative ions respectively.

If the molecule has the higher charge then the bond that it forms with other molecules is very strong and has higher polarity hence greater amount of heat energy is required to break this bond increasing the melting point of the substance.

The bonds formed between the molecules are either polar or can be nonpolar depending upon the electron pair exchanged between the molecules and the electro-negativity. If one of the molecules among the two has higher electronegative polarity then it forms a stronger bond.

Do polar covalent bonds have low melting points?

The polar covalent bonds have a low melting point because of the van der Waal’s force of attraction between the molecules.

The covalent bond between the two molecules is a short ranged force of attraction between the molecules and hence this force of attraction is easily overcome by supplying a small amount of heat energy.

The hydrochloric molecule is polar molecule chlorine is electronegative in charge and bonds with the hydrogen atom that has only one electron. The hydrogen becomes positively charged upon donating its single electron.

The hydrogen atom is pulled towards the chlorine atom making HCl more electronegative thus making a covalent bond. You must have seen the fumes of hydrogen evaporating from the HCl beaker even at room temperature as the bonds between the hydrogen and chlorines break easily.

Does covalent bond affect melting point?

The covalent bonds are non-metallic bonds formed between the ions having similar polarity or close to sharing the electron pairs.

The covalent bonds show a weak force of attraction because the polarity is almost the same between the molecules bonding together thus these bonds lower the melting point of the matter.

The molecular force of attraction becomes weaker due to the covalent bonds between the atoms and hence less amount of energy is required to break these weak forces of attraction. Therefore the melting point of the matter shows the covalent bonding that the weak Van der Waal’s force is low.

Why do covalent bonds melt faster than ionic?

The covalent bonds are weaker than the ionic bonds and hence it is obvious that the melting point of covalent bonds is lower than the ionic.

The ionic bond forms the strongest lattice structure with small equal voids between the molecules while the covalent bonds between the atoms are a weak force of attraction and break easily.

melting point and polarity
Ionic bonds forming the crystal cell; Image Credit: pixabay

The ionic bonds connect multiple molecules together to form a structure of molecules developing the crystal and minerals of well-defined faces. The ionic bonds form the crystal lattice that requires huge energy to break this structure.

Is N2 a polar molecular bond?

N2 is formed by the combination of the two nitrogen atoms sharing three covalent bonds.

The pair formed by two nitrogen atoms having the same atomic number and sharing the same electronegativity is a nonpolar molecule.

Which matter has the highest melting point?

The matter which comprises the molecules that form the strongest bonds between each other will have the highest melting point.

The ionic bonds between the atoms are the strongest bonds and form the network of bonds developing the specific structure depending upon the bond length and hence have the highest melting point as compared to any other type of bonding.

How covalent bonds exist between the two molecules?

The covalent bonds are the weakest force of attraction also called the weak Van der Waal’s force of attraction.

These bonds are formed by sharing the valence electrons with the two interacting molecules to complete their outer shell and become stable atoms. The pair of electrons shared is a covalent bond.

How the ionic bond is formed?

The ion is formed when one atom gives or takes away the electron from the valence shell to become an electro-positive or negative ion.

These ions, when bonded together, form the strongest bond which is called the ionic bond where the electron is completely bonded with other oppositely charge ion without forming the electron pairs.

Conclusion

The melting point of those substances is higher which has higher polarity. The melting point of the polar molecules is greater as compared to nonpolar matter. The covalent bonds between the atoms lower the melting point while the ionic bonds strengthen the melting point of the matter.

AKSHITA MAPARI

Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn - linkedin.com/in/akshita-mapari-b38a68122

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