Chemical bonds an introduction to atomic and molecular structure pdf
File Name: chemical bonds an introduction to atomic and molecular structure .zip
- Introduction to Chemical Bonding
- MODULE -2 Chemistry Notes Atomic Structure and Chemical Bonding
- Chemical bond
In this paper we briefly review the basic requirements that must be satisfied by any wave function representing many-electron systems. Following that, we examine the conditions under which the classical concepts of molecular structure, chemical structure and chemical bond can be translated into a quantum-mechanical language. Essential to this aim is the utilization of an independent particle model IPM for a many-electron system. In spite of the great popularity of the Hartree-Fock HF model only Valence-Bond VB type wave functions with optimized, singly occupied and non necessarily orthogonal atomic-like orbitals, can provide a quantum-mechanical translation of the classical concepts of chemical structure and chemical bond, although the HF model can still be useful for translating the concept of molecular structure. Finally, a quantum-dynamical-type of analysis allows us to conclude that, from the quantum mechanical point of view, the chemical bond is a consequence of interference effects.
Introduction to Chemical Bonding
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. In quantum physics , organic chemistry , and biochemistry , the distinction from ions is dropped and molecule is often used when referring to polyatomic ions. In the kinetic theory of gases , the term molecule is often used for any gaseous particle regardless of its composition. This violates the definition that a molecule contain two or more atoms, since the noble gases are individual atoms. A molecule may be homonuclear , that is, it consists of atoms of one chemical element , as with two atoms in the oxygen molecule O 2 ; or it may be heteronuclear , a chemical compound composed of more than one element, as with water two hydrogen atoms and one oxygen atom; H 2 O.
MODULE -2 Chemistry Notes Atomic Structure and Chemical Bonding
All the atoms, except those of inert gases, participate readily in the formation of chemical bonding. It is necessary to understand the formation and nature of chemical bonds to arrive at the structures of molecules; study the interactions between them; and to understand the chemical reactivity. In simple words, the attraction between two atoms or ions that holds them together is known as chemical bond. A chemical bond may be formed either by sharing of electrons or by transfer of electrons between atoms i. This is the major difference between intermolecular forces of attractions van der Waals forces and chemical bonds.
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Chemical bonding is one of the most basic fundamentals of chemistry that explains other concepts such as molecules and reactions. Without it, scientists wouldn't be able to explain why atoms are attracted to each other or how products are formed after a chemical reaction has taken place. To understand the concept of bonding, one must first know the basics behind atomic structure. A common atom contains a nucleus composed of protons and neutrons, with electrons in certain energy levels revolving around the nucleus.
A chemical bond is a lasting attraction between atoms , ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole—dipole interactions , the London dispersion force and hydrogen bonding. Since opposite charges attract via a simple electromagnetic force , the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other. An electron positioned between two nuclei will be attracted to both of them, and the nuclei will be attracted toward electrons in this position.