Science and Technology for UPSC Examinations [Chemistry] Part 1- State of Matter

Matter can exist in at least four fundamental states viz. solid, liquid, gas and plasma. There are other states also but they don’t exist in our natural environment. One of them is Bose–Einstein condensate and another is neutron stars. Other states, such as quark-gluon plasmas, are believed to be possible.

• In solids, the constituent particles are held very close to each other in an orderly fashion and there is not much freedom of movement.
• In liquids, the particles are close to each other but they can move around.
• In gases, the particles are far apart as compared to those present in solid or liquid states and their movement is easy and fast.

Because of such arrangement of particles, solids have definite volume and definite shape; the Liquids have definite volume but not the definite shape. They take the shape of the container in which they are placed. The Gases have neither definite volume nor definite shape. Gases completely occupy the container in which they are placed. These states of matter are interconvertible by changing the conditions of temperature and pressure.

Plasma

Plasma is one of the four fundamental states of matter. Plasma is basically ionized molecules or atoms (charged particles: positive ions and negative electrons or ions). The Ionization can be induced by heat or other means, such as strong electromagnetic field applied with a laser or microwave generator, and is accompanied by the dissociation of molecular bonds, if present. Like gas, plasma does not have a definite shape or a definite volume unless enclosed in a container; unlike gas, under the influence of a magnetic field, it may form structures such as filaments, beams and double layers. Some common plasma are found in stars and neon signs. In the universe, plasma is the most common state of matter for ordinary matter, most of which is in the rarefied intergalactic plasma. Plasma can be found in the following instruments of everyday use:

• Plasma TV
• Neon Lights
• The area in front of a spacecraft’s heat shield during re-entry into the atmosphere
• The electric arc in an arc lamp, an arc welder or plasma torch
• Laser-produced plasmas (LPP), found when high power lasers interact with materials.
• Magnetically induced plasmas (MIP), typically produced using microwaves as a resonant coupling method
• Static electric sparks

Mixtures and Pure Substances

• At the macroscopic or bulk level, matter can be classified as mixtures or pure substances.
• The mixtures can be homogenous mixtures or heterogenous mixtures.
• In a homogeneous mixture, the components completely mix with each other and its composition is uniform throughout. Sugar solution and air are examples of homogeneous mixtures.
• In heterogeneous mixtures, the composition is not uniform throughout and sometimes the different components can be observed. Mixtures of grains and pulses along with some stone particles are heterogeneous mixtures.
• Pure substances have fixed composition, whereas mixtures may contain the components in any ratio. Pure substances are divided into Elements and Compounds.
• An element consists of only one type of atoms or molecules. When two or more atoms of different elements combine, the molecule of a compound is obtained.