PLASMA, ITS FORMATION AND TYPES - FIRST YEAR CHEMISTRY

Plasma, Its Formation and Types

Plasma

• Plasma is a hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons. 
• Plasma is often called "fourth state of matter", the other three being solid, liquid and gas. 
• Plasma was identified by the English scientist William Crookes in 1879. 
• Plasma is estimated to constitute more than 99 percent of the visible universe. 
• Although, naturally occurring plasma is rare on earth, there are many man-made examples.  
• It occurs only in lightning discharges and in artificial devices like fluorescent lights, neon signs etc. 
• It is everywhere in our space environment. All the stars that shine are all plasma. 

 How is Plasma Formed?

     When more heat is supplied, the atoms are molecules may be ionized. An electron may gain enough energy to escape its atom. This atom loses one electron and develops a net positive charge. It becomes and ion. In a sufficiently heated gas, ionization happens many times, creating clouds of free electrons and ions. However, all the atoms are not necessarily ionized, and some of them may remain completely intact with no net charge. This ionized gas mixture, consisting of ions, electrons and neutral atoms is called plasma. 

     It means that plasma is a distinct state of matter containing a significant number of electrically charged particles, a number sufficient to affect its electrical properties and behaviour. 

Types of Plasma

     There are two types of plasma, artificial plasma and natural plasma.

(i) Artificial Plasma: Artificial plasma can be created by ionization of a gas, as in neon signs. Plasma at low temperatures is hard to maintain outside a vacuum, low temperature plasma reacts rapidly with any molecule it encounters. This aspect makes this material, very useful and hard to use. 

(ii) Natural Plasma: Natural plasma exits only at very high temperatures, or low temperature vacuums. Natural plasma does not breakdown or react rapidly, but is extremely hot (over 20,000⁰C minimum). Their energy is so high that they vaporize any material they touch. 

Notes Prepared By: Prof. Shahbaz Asghar