Class 12 Types Of Crystalline Solids

 The term “real solids” refers to crystals or crystalline solids. One example of this kind of solid is regular table salt. Atoms, ions, or molecules are arranged in crystalline solids in an organized and symmetrical pattern that is repeated throughout the crystal. So in this article, we will study different types of crystalline solids.

One category of solid-state compounds is crystalline solids. Solids are substances with a melting point at atmospheric pressure that is higher than room temperature. Solids can be classified into two categories: amorphous solids and crystalline solids, depending on how their constituents are arranged. Crystalline solids are those that contain their component atoms, molecules, or ions in a regular, three-dimensional configuration. Crystalline solids include things like sodium chloride, quartz, diamond, etc.

Properties of Crystalline Solids

• They have distinct symmetries and forms.
• They are inflexible and unyielding.
• Their melting point is high.
• Together, they make up a crystalline system.

Eventually freezing and becoming crystalline solids when most liquids are cooled, these solids have their atoms, ions, or molecules organized in a distinct, repeating pattern. A liquid could also freeze before its molecules are arranged in an organized way. The materials that are produced are referred to as amorphous solids or noncrystalline solids (or, sometimes, glasses). Such solids’ particles lack an ordered internal structure and are distributed haphazardly.

Here are the types of crystalline solids

Molecular Solids

The majority of molecular solids are low in density, soft, and insulators. Molecular solids include substances like sugar, solid halogens, sulphur, and ice (made of water). Even molecular solids themselves are divided into various sorts.

Non–Polar Molecular Solids

Since the electron distribution in such materials is symmetrical, no side of the solid has an excessive amount of charge. Charges on either side cancel each other out. Methane, chlorine, hydrogen, and oxygen are among the examples. They are liquids or gases when the temperature and pressure are normal. Vander Waals forces are what bind or hold the molecules together in these solids (weak dispersion or London forces). In comparison to ionic or covalent bonds, these forces are weaker.

Polar Molecular Solids

These solids have a geometry where one side is positively charged and the other is negatively charged. They are being attracted to one another by a dipole-dipole force. Even though they have higher melting and boiling temperatures than non-polar molecular solids, they are still quite low. Polar compounds include ethanol and ammonia, for instance.

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Hydrogen-Bonded Molecular Solids

Strong hydrogen bonds act as the intermolecular forces in these types of materials. They have greater melting and boiling points than polar and non-polar molecular solids. They exist at room temperature and pressure as flammable liquids or soft solids. A molecular liquid with hydrogen bonds is water.

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1. Ionic Solids

Ionic solids of the Crystalline Solids contain anions (negatively charged particles) and cations as constituent particles (positively charged). A typical number of opposing charges surround an ion. For instance, in NaCl, there are six Cl- ions around the Na+ ion. Strong electrostatic forces hold the ions in these solids together. They are soluble in polar solvents but not non-polar ones and have high melting and boiling temperatures.

2. Covalent Solids or Network Solids

Why do covalent solids exist? Covalent bonds hold the atoms of molecules together in these substances. Thus, a huge molecule forms as a result of the crystal’s network of interconnected covalent bonds. With the exception of graphite, which is a good conductor, they have high melting and boiling temperatures and are generally poor conductors (due to the fourth electron being free).

3. Metallic Solids

Metallic solids are what? The constituent elements of these solids are metal atoms, which can gain or lose valence electrons and become positively charged as a result. The crystal’s surface is covered with a sea of electrons that are free to move around. Metallic bonds occur as a result of the attraction between positively charged ions and a sea of electrons. The metal ions are held together by this force. The structure of metallic solids is regular, and they have high melting and boiling temperatures. They possess a high degree of thermal and metallic conductivity due to the sea of electrons. Metallic solids include all metals and alloys.

Summary

• A mixture of positive and negative ions makes up ionic crystals.
• In metallic crystals, a “sea” of movable valence electrons surrounds the metal cations.
• The covalent crystals are composed of atoms that are bonded to one another covalently.
• Crystals of molecules are held together by weak intermolecular forces.

Hope you have now understood the different types of crystalline solids and if you have any queries or want to share something more about types of crystalline solids then do mention them in the comment box.