2.1 STATE OF MATTER

There are four states of matter:

  1. Gas
  2. Liquid
  3. Solid
  4. Plasma

Each state is a distinct form of matter.

  1. States of matter are the different forms in which matter can exist. These are solids, liquids, gases, and plasmas. These states are determined by the arrangement and movement of particles and the strength of intermolecular and atomic forces.
  2. Energy can change matter into different states. For example, solids become liquids or gases when heated. At very high temperatures or when subjected to a strong electric field, the gas transforms into plasma. Under normal conditions, most substances remain in one distinct state: solid, liquid, or gas. Temperatures and energy levels on the Earth are not sufficient to ionize atoms and create plasma.
  3. When heated, some crystalline solids turn into cloudy liquids. This cloudy state is called liquid crystal. Liquid crystal states have many properties of liquids and some properties of solids. This form exists within a certain temperature range. When heated further, the state of the liquid crystal changes to a transparent liquid.
  4. Furthermore, there are other states such as Bose-Einstein Condensates (BEC) which is defined as the state of matter in which separate atoms cooled to temperatures very close to absolute zero. BEC is observable under extreme conditions of cold temperature. Superfluid and superconductors are the two main materials which contain BEC.

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Can

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liquid

gaseous

plasma

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Energy/Temperature

Molecule

Molecule (excited)

lons

Molecular fragment (high energy)

Free electron

Figure 2.1: State of Matter

Macroscopic properties can be visualized by the naked eye, and we can measure them easily. Some common examples of macroscopic properties of matter include density, fluidity, compressibility.

State of matterDensityCompressibilityFluidity
GasLow density at normal condition due to large spaces between moleculesVery compressible because of large empty spacesCan flow
LiquidHigh density at normal conditionModerately compressibleCan flow
SolidHigh density at normal conditionNot compressibleCannot flow

Have you ever boiled water on a stove? What do you observe when the water heats up? Bubbles form and the water turns into the gas. This tells us a very important fact about the states of matter. Though the states of matter are distinct and are easily distinguishable from the other, through physical techniques we can convert one state of matter into the other. Physical techniques are techniques where we manipulate the physical aspects of matter such as the temperature or pressure. However, the chemical composition of matter stays the same.