Define the following terms: Directional bond, lonic bond, Metallic bond, lon, Valence. Define the following mechanical properties: Hardness, Toughness, Malleability, Hardenability, Ductility.

QUESTION ONE

a) Define the following terms:

i. Directional bond: A chemical bond where the electron density is concentrated in specific directions in space, leading to fixed bond angles and molecular geometries. Covalent bonds are typically directional.

ii. Ionic bond: A chemical bond formed by the electrostatic attraction between oppositely charged ions, which results from the complete transfer of one or more valence electrons from one atom to another.

iii. Metallic bond: A type of chemical bond found in metals, characterized by a "sea" of delocalized valence electrons shared among a lattice of positively charged metal ions.

iv. Ion: An atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons.

v. Valence: The combining capacity of an element, typically determined by the number of electrons an atom gains, loses, or shares to form chemical bonds.

b) Define the following mechanical properties:

i. Hardness: The resistance of a material to localized plastic deformation, such as indentation, scratching, or abrasion.

ii. Toughness: The ability of a material to absorb energy and plastically deform before fracturing. It is a measure of a material's resistance to crack propagation.

iii. Malleability: The ability of a material to deform under compressive stress (e.g., hammering or rolling) without fracturing, allowing it to be shaped into thin sheets.

iv. Hardenability: The ability of a ferrous alloy to be hardened by heat treatment, specifically the depth to which a material can be hardened from its surface.

v. Ductility: The ability of a material to deform under tensile stress (e.g., stretching or drawing) without fracturing, allowing it to be drawn into a wire.