Wonders of Chemistry: Why carbon is solid and Nitrogen is gas at room temperature while sitting next to each other in the periodic table
At high enough temperatures, all elements acquire a gaseous state where entropy is large. The molecular properties of a substance control its state of matter under a given set of conditions, not the other way around. The presence of strong intermolecular forces favors a condensed state of matter (liquid or solid), while very weak intermolecular interaction favors the gaseous state. In addition, the shape of the molecules dictates whether a condensed phase is a liquid or a solid.
Question: Intermolecular potential energy [ not chemical bond energy] is clean energy. This energy can be put to use if we can separate molecules. The process can be repeated again and again by bringing the molecules closer and generating potential energy that could be by means of compression. Why we do not look at sources of energy created by induced dipoles like van der Walls or London dispersion forces in carbon which has a huge network of atoms and it has a huge surface that facilitates induced dipoles generation. . This energy may not be as much potential energy that is stored in chemical bonds. But this can be a renewable source of energy as you do not destroy the molecules.
Carbon vs Nitrogen
Nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. A nitrogen atom has seven electrons. It has one of the highest electronegativities [affinity for electrons] among the elements (3.04 on the Pauling scale), exceeded only by chlorine (3.16), oxygen (3.44), and fluorine (3.98). At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2. Dinitrogen forms about 78% of Earth's atmosphere. Nitrogen occurs as diatomic molecules with very low lower melting (?210 °C) and boiling points (?196 °C. N2 molecules are only held together by weak van der Waals interactions and there are very few electrons available to create significant instantaneous dipoles.
Carbon
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent-making four electrons available to form covalent chemical bonds. The atoms of carbon can bond together in diverse ways, resulting in various allotropes of carbon. The best-known allotropes are graphite, diamond, and buckminsterfullerene.
Gas vs solid: Gases have the lowest density of the three phases gas, liquid and solid. Gases are highly compressible. Gases behave this way because their intermolecular forces are relatively weak. In gases, molecules are constantly moving independently of the other molecules present. Solids, in contrast, are relatively dense, rigid, and incompressible because their intermolecular forces are so strong that the molecules are essentially locked in place.
What are the intermolecular forces?
Intermolecular forces (IMF) are the forces that control the interaction between atoms, including forces of attraction or repulsion which act between atoms and other types of neighboring particles, e.g. atoms. Intermolecular forces are weak relative to intramolecular forces
Dipole-Dipole interactions
Dipole-dipole interactions are electrostatic interactions between molecules that have permanent dipoles. When one end of the molecule has more affinity for electrons that acquires a negative charge and the other end has a positive charge. These two charged ends become two permanent poles of positive – negative attraction and positive – positive and negative-negative repulsion.
London dispersion forces
The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed unsymmetrically about the nucleus. This force is sometimes called an induced dipole-induced dipole attraction.
How these forces occur?
Dispersion forces are present between all molecules, whether they are polar or nonpolar. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles.
In a gas, the distances between molecules are generally large, so intermolecular forces have only a small effect.
Nitrogen vs Carbon
Intermolecular forces of Nitrogen vs Carbon
N2 has very weak intermolecular forces which make it a gas.
Nitrogen gas (N2) is diatomic linear and non-polar because both nitrogen atoms have the same degree of electronegativity and they cancel each other. There are no dipoles, which would make the nitrogen atoms stick together. However, weak London dispersion forces do exist by means of the creation of temporary dipoles. On the whole, electron affinity or combining ability for N2 is only 7 kj/mol while carbon has a huge number 154 kj / mol.
All put together N2 has very weak intermolecular forces
A single carbon atom can only exist in the gas phase. Carbon has several allotropes or different forms in which it exists. Carbon has four electrons available to form covalent chemical bonds. Carbon exists as a covalently bonded network of carbon. Each carbon atom is covalently bonded to four other carbons in a tetrahedron. This stable network of covalent bonds and hexagonal rings is the reason that diamond one of the allotropes of carbon is so incredibly strong as a substance. Carbon because of its structure with the large three-dimension surface area has a significant amount of London dispersion forces which makes it solid.
Credit: Google