Tag: chemistry

Metallic bonding may be described as the sharing of free electrons among a lattice of positively charged metal ions. The structure of metallic bonds is very different from that of covalent and ionic bonds. While ionic bonds join metals to nonmetals, and covalent bonds join nonmetals to nonmetals, metallic bonds are responsible for the bonding between metal atoms. In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize. That is to say, instead of orbiting their respective metal atoms, they form a sea of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions. The electrons then move freely throughout the space between the atomic nuclei.

In a metallic bond, electrons are shared with more than one atoms. Due to this, the valance electrons are spread all over the crystal. Hence, metallic bonds are non-directional.

Metallic bonding is the strong attraction between closely packed positive metal ions and a 'sea' of delocalised electrons. So,high energy is required to overcome this bond, hence high temperature can be used to weaken or overcome these attractive forces.

(A) : The model of metallic bonding where electrons float free in a sea of electrons around metal atoms.
This model proposes that all the metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electron. The electrons present in the outer energy levels of the bonding metallic atoms are not held by any specific and can move easily from one atom to the next.

The electrons can move freely within molecular orbitals, and so each electron becomes detached from its parent atom. The electrons are said to be delocalised. The metal is held together by the strong forces of attraction between the positive nuclei and the delocalised electrons.This is sometimes described as "an array of positive ions in a sea of electrons".

Contaminated water can cause many types of diarrheal diseases, including cholera, and other serious illness such as guinea worm diseases, typhoid, and dysentery.

Water pollution is the second most imperative environmental concern along with air pollution.

Industrial or man-made concentrations of naturally occurring substances, such as nitrate and ammonia associated with livestock manure from agricultural operations, have also been identified as health hazards in soil and groundwater.

Contaminated or polluted soil directly affects human health through direct contact with soil, or via inhalation of soil contaminants which have vaporized. Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia. 

Any form of pollution that can trace its immediate source to industrial practices is known as industrial pollution.
Industrial pollution takes on many faces. It contaminates many sources of drinking water, releases unwanted toxins into the air and reduces the quality of soil all over the world