Question

1.) Define the following terms as completely as possible giving diagrams where appropriate:-

Electronegativity (5pts)

Solid solubility and what factors affect its limit (10pts)

Burgers vector of an edge dislocation (5pts)

Give the electronic configuration Kr Atomic Number 36 (5pts)

Answer 1

# Electronegativity is a measure of how strongly atoms attract bonding electrons to themselves. The higher the electronegativity ,the greater an aom attracts electrons.

It describes the tendency of an atom to attract a shared pair of electrons.

It is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus.

With increase in oxidation state of an element,the electronegativity also increases.

The electronegativity changes with the hybridization of the orbital in the bonding. The elctonegaivity is more in sp orbital than sp² and sp3  orbitals.

# Solid solubility is the dissolving ability of a foreign element in the host crystal.A solid soution forms when the solute atoms are added to the solvent provided that the solvent crystal structure is maintained.Here,the solvent denotes the host crystal that is present in major concentration and the element that is present in minor concentration is referred as solute.The dissolving ability of solute in the solvent is called solid solubility.

The factors affecting solid solubility are:

*Atomic size difference:

The dissolution of solute in the solvent is more if the difference between the atomic radii of the two is less than +/-15%. The solute atoms create significant lattice distortion of the solvent crystal when the atomic radii of the two is more than that and a new phase will form.

*Crystal structure:

The solid solubility is more if the crystal structure of both the solute and the solvent is the same.

*Electronegativity

*Valence electron concentration

*Temperature:

Endothermic reaction increases the solid solubility whereas the exothermic reactions decrease the solid solubility.

*Surface area:

The solid solubility increases when the surface area is increased.

# A dislocation is a line defect in a crystal. For an edge dislocation ,the Burgers vector is parallel to dislocation motion and perpendicular to the dislocation line.

An edge dislocation is a defect where an extra half plane of atoms is introduced midway through the crystal,distorting nearby planes of atom.This extra plane passes through planes of atoms breaking and joining bonds with them until it reaches the grain boundary when enough force is applied from one side of the crystal structure.

The burgers vector describes the magnitude and direction of distortion to the lattice.

The stresses caused by an edge dislocation are complex due to its inherent asymmetry.

sigma_xx = [(~mu*b/2pi (1-gamma)]*[y*(3x²+y²)/(x²+y²)²]

where mu is the shear modulus of the material,b is the Burgers vector, gamma is the poisson's ratio and x and y are the coordinates.

# The electronic configuration of Kr is 1s²,2s²,2p⁶,3s²,3p⁶,3d¹⁰,4s²,4p⁶

^{This totals up to 36 electrons.}