Why is plasma considered as the fourth state of matter?

Plasma is considered the fourth state of matter because it exhibits properties distinct from solids, liquids, and gases. Here are key reasons why plasma is classified as such:

1. Ionization: Plasma is characterized by the presence of ions and free electrons, which are not bound to atoms. This ionization occurs when a gas is heated to high temperatures or subjected to strong electromagnetic fields, causing atoms to lose electrons and become ions13.

2. Electrical Conductivity: Unlike gases, which are poor conductors of electricity, plasmas are highly conductive due to the free movement of charged particles. This conductivity allows plasmas to respond strongly to electromagnetic fields13.

3. Collective Behavior: In plasmas, the interactions between charged particles are long-range, leading to collective phenomena such as plasma waves and instabilities. This is in contrast to gases, where interactions are primarily short-range and binary1.

4. Abundance in the Universe: Plasma is the most common state of matter in the universe, found in stars, including the Sun, and in interstellar and intergalactic media15.

5. Unique Properties: Plasmas can be influenced by magnetic fields, exhibit quasineutrality (where the overall charge is roughly zero), and display complex dynamics not seen in other states of matter13.

Overall, plasma's unique characteristics set it apart from the other three states of matter, solidifying its position as the fourth state.