class 12 The Solid State Memorization tricks

 Let's quickly learn the important figures and facts in 5 minutes

1

Confused with 7 Crystal Systems? Here's what can help you!

Based on the parameters, such as length and angle, there are seven types of unit cells. Can you name them without holding back?

Just remember this one line, and you will be able to recall the 7 crystal system

Old china town is a Top Rated Historical Movie

S.No	What to remember?	Crystal System
1	Old	Orthorhombic or Rhombic
2	China	Cubic
3	Town is a	Tetragonal
4	Top	Triclinic
5	Rated	Rhombohedral or Trigonal
6	Historical	Hexagonal
7	Movie	Monoclinic

If you find it helpful, do remember to share this trick with your friends.

Apart from this, you need to remember the edge lengths and the axial angles. It's pretty simple, if you can visualise the structure.

Let's start with the simplest ones

Cubic System: It's a cube with equal sides and all angles equal to 900.

Rhombohedral: Like in a Rhombus, it has equal sides. It's like a square but with angles NOT EQUAL to 900.

Tetragonal: Similar to a cube but one side is longer. Therefore, a=b=c.

Moving on to the more complex ones:

Hexagonal: Similar to tetragonal but one of the angles is equal to 120o.

Orthorhomic: Do not confuse it with the structure of a rhombus. The term ''ortho'' means right. So, all the angles are right angled or 90o. For the sides: rhombic sounds a little like random. The sides of an orthorhombic structure are random.

Monoclinic and Triclinic: All the sides are different.

Monoclinic - Mono stands for one. There is one angle which is not equal to 90o.

Triclinic - Tri stands for three. All the three angles are not equal to 90o.

2

Do you tend to mix up the terms in the expression of density of unit cell? Here's what can stop you!

There are a lot of questions asked regarding the density of a cubic crystal. Many times we mess up the terms and apply the wrong formula. There is a way to avoid this.

To recall the formula of density of the unit cell, you just need to remember this silly sentence, which is-

Zebra and Monkey Don't Like Agra and Nagaland

Density of cubic crystals :

ρ=a3XNo​Z X M​

Here.

Z = Number of particles present per unit cell

M = Molar mass

ρ=Density of the crystal

a=Edge of the unit cell

No​=Avogadro’s number

3

So many stoichiometric defects, how to remember them? Let's find out!

Defects in crystals refer to departure from perfectly ordered arrangement of constituent particles. There are different types of defects - point and line defects. In point defects, the major ones are stoichiometric, non-stoichiometric and impurity defects. Out of these, stoichiometric defects are the most popular ones in the exams. Do you tend to forget the different types. Let me help you here!

My School teaches French in a very interesting way

Now. you can easily remember these terms-

1. School - Schottky
2. French- Frenkel
3. Very - Vacancy
4. Interesting - Interstitial