Content Curator
Matter can be referred to as anything that occupies space. Atoms formed of electrons, protons and neutrons provide the base for every type of matter. Chemical energy can be referred to as a kind of potential energy that confines the atoms and molecules together. Matter can be said to be anything that has an amount of mass and volume.
| Table of Content |
Three States of Matter: Definition
[Click Here for Sample Questions]
There are four states of matter that can be enlisted, namely solids, liquids, gases and plasma. There are other forms of matter as well, namely, Bose-Einstein condensate and neutron degenerate matter, which takes place only in case of extreme conditions - very cold or very dense matter. Some other states can be referred to as quark - gluon plasma is considered possible, however they are said to be theoretical for the time being.
The most commonly known three states of matter can be referred to as solids, liquids and gases. Solids have a very tight atomic bond along with a high viscosity which gives them a rigid form. Most of the solids are in a crystalline state and the periodic atomic structure is in a three dimensional form. Solids like glass are devoid of such periodic arrangement and are in a crystalline or amorphous state. The forces between the particles (ions, atoms or molecules) are very strong and lack free movement and can only vibrate. Solids contain a consistent and particular shape along with a definite volume. They can only alter their formation only through the application of force.
Solids
A liquid can be considered as an incompressible fluid that takes the shape of its container but maintains a consistent volume irrespective of the pressure. Volume can be defined only if the pressure and volume is fixed. When heat is applied to a solid beyond its melting point, it turns into liquid due to the pressure exceeding the triple point of the matter.
Liquids
The molecules within a gas have kinetic energy to a great extent such that the effect of the intermolecular force seems smaller and the usual distance between the adjoining molecules is larger than the size of the molecules. Gas doesn't have any particular shape but takes up space of the container in which it confines.
Gases
Three States of Matter: Properties
[Click Here for Sample Questions]
The three states of matter which are present in our environment are three different physical forms as explained below:
Solid
- Solids are one of the basic forms of matter.
- They are relatively rigid and differ in characteristics from liquids and gases.
- Solids have a stable volume and shape.
- In a cube, atoms and molecules are tightly attached to one another. They vibrate in a particular place but do not move.
- Solids have a fixed shape and volume.
- They contain very little compressibility and thermal expansion.
- Solids can be changed to liquids only if heat is applied to the solids to a point where they begin to melt.
- Example: Fe (Iron)
Liquid
- Liquids have a constant volume and are capable of changing shape by flowing.
- In a fluid, atoms, and molecules adhere loosely. They roam around but live side by side.
- They are weaker than solids but stronger than gases.
- Liquids can be changed into solids through solidification and into gases through evaporation.
- The compressibility and thermal expansion of liquids are higher than solids.
- Example: H2O (Water)
Gas
- Gases do not have any exact volume or shape.
- They have very little intermolecular force and atoms and molecules move freely, separated from each other.
- Rotatory, Vibratory and Translatory motions can be observed in case of gases.
- They possess the highest compressibility and thermal expansion among solids, liquids and gases.
- They can be turned into liquid through condensation.
- Example: O2 (Oxygen)
Three States of Matter: Ways to Determine
[Click Here for Sample Questions]
The states of matter can be determined by considering three components present in the matter:
- The level of kinetic energy as an impact of the motion of the particles.
- The attraction force between the atoms.
- Space between particles.
When there is a presence of high kinetic energy, the force between particles is very less and there is an absence in the space between particles. This state of matter is called gaseous state.
If the space between particles is decreased, the exerted amount of kinetic energy is very less and the force is very high, then the matter can be referred to as a solid.
When there is a presence of strong interparticle force between the atoms, the space between the particles increases due to enough kinetic energy. This keeps the particles moving persistently and the matter can be referred to as liquid.
Three States of Matter: Sample Questions
Short Answer Questions
Ques. What are Van der Waals forces? (1 mark)
Ans. Van der Waals forces are weak intermolecular forces that depend upon the space between atoms. These forces are generated by interactions between uncharged molecules.
Ques. At what temperature will the quantity of gas at 00 c double itself, pressure remaining constant? (2 marks)
Ans. Let the quantity of the gas at 00C be Vml.
Thus,
V1 = Vml, V2 = 2Vml
T1 = 273, T2 =?
= 273k
Using Charles’ Law
= > T2 = 546 - 273 = 273°C
Ques. Explain how the pv / RT function can be used to show that gases do not behave ideally at high pressures. (1 mark)
Ans. The pv / RT ratio is equal to the number of moles of the ideal gas in the sample. This number should be stable for all the conditions of pressure, volume, and temperature. If the value of this ratio changes with increasing pressure, the gas sample will not behave ideally.
Ques. What are the three types of cubic unit cells? (2 marks)
Ans. a) Primitive Cubic Unit Cell - In a primitive cubic unit cell, the molecules are present only at the corners.
b) Body-centered Cubic Unit Cell - A BCC unit consists of one atom at each corner of the cell cube and one atom in the center of the structure.
c) Face-centered Cubic Unit Cell - An FCC unit cell consists of molecules at all corners of the crystal lattice and between all faces of the cube.
Ques. What is the relation between the density and edge length of a cubic crystal? (2 marks)
Ans. Density, d of a cubic crystal is given as-
Where Z = no. of atoms per unit cell
M = molar mass
= Avogadro number
a = edge length
Long Answer Questions
Ques. Explain electrical conduction based on band theory. (3 marks)
Ans. The conductivity of metals depends on the number of valence electrons available to each atom. The atomic orbits of metal atoms from molecular orbits are so close to each other that a band is formed. If this band is partially filled and has a high energy gap, overlapping with the conduction band, the electrons can flow freely under the applied electric field and the metal conductor. If the gap between the filled valence band and the conduction band is large, the electron will not jump on it and the material will be an insulator, but if the gap is small and can be overcome when heated, the material will act as a semiconductor.
Ques. What is a semiconductor? What are the two main sorts of semiconductors? (5 marks)
Ans. Semiconductors are materials that conduct conductivity between conductors and non-conductors or insulators.
There are two types of semiconductors-
- n-type semiconductor –
- Mainly due to electrons
- Completely neutral
- Electrons – Majority
- Holes- Minority
When a pure semiconductor (silicon or germanium) is doped with a pentavalent impurity (P, As, Sb, Bi), four of the five valence electrons form four bonds with Ge or Si electrons.
Dupont's fifth electron becomes free. Thus, the impure atom donates free electrons for circulation in the lattice and is called a "donor".
As the number of free electrons increases along with the impurity, there is an increase in the negative charge carriers. Hence, it is known as an n-type semiconductor.
The crystal as a whole is neutral, but the donor atom becomes a stable positive ion. Due to a large number of free electrons in the conduction, electrons are the main carriers and holes are the minority carriers in n-type semiconductors.
- p-type semiconductor
- Mainly due to holes
- Completely neutral
- Holes – Majority
- Electrons - Minority
When the pure semiconductor is doped with triplet purification (B, Al, In, Ga), three valence electrons of impure bond with three of the four valence electrons of the semiconductor.
This leaves no electron (hole) in the impurity. These impure molecules that are ready to accept bonded electrons are called "acceptors".
As the number of impurities increases, the pores (positive charge carriers) increase. Hence, it is known as a p-type semiconductor.
The crystal is entirely neutral, but the receiver becomes a constant negative ion. Due to a large number of holes in the conduction, the main carriers and electrons in the p-type semiconductor holes are the minority carriers.
Comments