Category: Chemistry Course

Quantum numbers and their calculation

Definition: Quantum numbers are a set of four values that are used to describe the position and energy of the electron in an atom. Alternatively, quantum numbers are the numbers used to indicate the size, shape, three-dimensional direction, variation of the energy level, and the direction of rotation of an electron around its own axis. Four quantum numbers are required to fully describe the position of electrons in an atom…

(n+l) rule and its applications

(n+l) Rule From this rule, we can get information about the difference in energy between two orbitals. According to the Aufbau principle, electrons are filled into atomic orbitals in the increasing order of orbital energy level.(n+l) rule helps to determine which one between two given orbitals will occupy by an electron. As we know that there are four quantum numbers, namely, principal(n), azimuthal(l), magnetic(m), and spin(s) quantum numbers. They are…

Ionization Potential on The Basis of Molecular Orbital Theory(MOT)

The ionization potential of N-atom is 14.53 eV whereas this value for N2 molecule is 15.56 eV The electronic configuration of N-atom is 1s22s22p3 . The 1st ionization potential of N-atom can be expressed as: On the other hand, the electronic configuration of N2 molecule according to MOT can be given as: One electron is eliminated from π2Px bonding orbital during the ionization process. From the above diagram, we can…

Diborane: Synthesis, Production, Physical and Chemical Properties

Definition: It is a chemical compound that consists of B and H-atoms. Has a molecular formula B2H6, which is the simplest boron hydrides. B2H6 is unstable at the room temperature with a sweet smell B2H6 will ignite rapidly at room temperature B2H6 mix well with the air forming explosive mixtures Production and Synthesis ( Source: Wikipedia): Industrial synthesis of diborane: Diborane is produced on a large scale by the reduction…

Electron Deficient Compounds

Definition Electron deficient compounds are those in which the total number of atomic orbitals on all the atoms of the compound is more than the total number of valence shell electrons. Boranes are electron deficient compounds: B = 1s22s22px12py2pz H = 1s1 B2H6 * number of orbitals from 2 B = 2 X 4 = 8     number of orbitals from 6 H = 6 X 1 = 6 Therefore,…

STYX number and Its Applications

Each boron is attached to at least one hydrogen atom by a two-electron sigma bond. The three-centered B-H-B bond is denoted by S, the closed or free three-centered B-B-B bond is expressed as t, the two-centered B-Ht and B-B bond is denoted by x and y, respectively. As we know that boron compounds are electron-deficient compounds. But if each boron atom forms a three-centered bond, then the bond electron deficiency…

Periodic properties: Electronegativity

When two different atoms in a molecule are bonded together by a covalent bond, the electron pair forming the the covalent bond is not shared equally by both the atoms. The relative ability of a bonded atom in a molecule to attract the shared electron pair towards itself is termed as its electronegativity. Factors affecting the magnitude of electronegativity: Size of the atom: The smaller atoms have greater electronegativity values…

Periodic Properties: Ionization Potential

Definition of ionization potential: The amount of energy needed to remove the most loosely bound electron from isolated neutral gaseous atom from its gaseous state to convert it into a unipositive gaseous cation. Unit: eV/atom ( 1 eV = 96.4705 KJ/mole = 23.06 Kcal/mole) Kcal/mole ( 1 Kcal/mole = 4.185 Kj/mole) KJ/mole Factors effecting the magnitude of Ionization Potential Effective nuclear charge: Greater is the magnitude of effective nuclear charge,…

Periodic Properties: Ionic radii (Part-02)

Size of anion: An anion is formed by adding one or more electrons to the neutral atom. F = 1s22s22p5 , F– = 1s22s22p6 O = 1s22s22p4 and O2- = 1s22s22p6 An anion has more electrons than its parent atom. With the increase of the number of electrons, the magnitude of the screening constant also increases. Therefore, the magnitude of the effective nuclear charge also decreases. The decreased effective nuclear…

Periodic Properties of Elements

The elements belonging the same group have similar properties. We have to pass 2, 8, 8, 18, 18, 32 and 32 elements before we come across an element with similar properties. The repetition of the elements with similar properties in the order of increasing atomic number as in the periodic table is called periodicity of properties and 2,8, 18 and 32 are called magic numbers. Causes of periodicity of properties:…

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