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Structure of matter

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  • This universe is made up of matter and energy

Matter: Thinks which has mass and occupies space is called matter

        Ex: Book, Table, clouds, stones, air, water, iron, plants and even a small drop of water or a particle off sand…etc.

  • Matter is made up of particles .The particles of matter are very small and their size is beyond our imagination.
  • Atom: An atom is defined as the smallest particle of an element which takes part in the chemical reaction.
  • An element is made up of the same kind of atoms.
  • Element: An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
  • Classification of matter:
  • There are about 117 different elements known to us. Out of these, 92 elements occur naturally on the earth. The other has been made by scientists in laboratories.
  • Compound:  A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion by weight.

Ex: Water contains Oxygen and hydrogen, similarly Carbon dioxide contains Carbon and Oxygen.

  • Mixtures: A mixture is a substance which consists of two or more elements or compounds of different types which are not chemically combined together.
  • NaCI in water, Sand in water, Chalk in water, Air etc.
  • Symbol: A short hand notation of an element is known as symbol.

Ex: ATM- Automated teller machine, SBI- State bank of India...

Similarly Oxygen-O,

Hydrogen-H

Elements symbols and Atomic Numbers

 

Name of the Element

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Atomic Number

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  • Atomicity: The number of atoms present in a molecule of an element is known as its atomicity.
  • Some elements can exist independently.   Ex: Helium-He, Neon-Ne they are known as monoatomic elements.
  • Valency:  A measure of the combing capacity of an element or a group.
  • The valency of an element or a group denotes it’s combining capacity. It is the number of hydrogen atoms which can combine with or be displaced by one atom of that element.
  • We can write the formula of a compound, if the valencies of its constituent elements/ groups are known.
  • A chemical equation shows the result of a chemical reaction in which the reactants and the products are represented by symbols or formulae.
  • An equation must be balanced, i.e. the number of atoms of each element should be the same on both sides of the equation.

Ex: N2+ H2→ NH3 (Unbalanced)

  1. + 3H2→ 2NH3 (Balanced).

 

References

living science
posted Apr 16, 2018 by Ramu Kollam

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My Encounter With JEE

 

JEE is all about the journey — the dream to get into an IIT, the preparation phase, the excitement of studying in one of the top educational institutes in India. In this post, I’ll share with you the insights of my encounter with JEE.

My encounter with jee : The beginning

Before coming to class 11, I was sure that I will be pursuing a career in engineering. My parents wanted to wait for my board exam marks so as to be sure if I had the right “aptitude” for engineering. However, board exam results and the engineering aptitude have little correlation. In class 10 boards, many students get good results, which is certainly not true for JEE. To get into an IIT, you need to be in the top 10000 students out of the 1.5 million students who appear for JEE.

I was admitted to a JEE coaching institute in class 11. Since I wanted to pursue engineering, I wanted to do my B.Tech from one of the most premier institutes in India. To achieve what I wanted, I had no other option than to study hard and crack the JEE to get into an IIT.

My encounter with JEE: The preparation phase

The JEE preparation phase is the most crucial phase of any IIT aspirant. This is the phase that can make your dream of studying in an IIT a reality or shatter it completely. I was well aware that if I had to get what I wanted, I cannot afford to waste time and resources during this phase.

This is the phase when there are lots of distractions. Your friends might want to bunk classes and go out for a movie instead. Some students skip the class tests too. Some students just come to the classes but the play mobile games instead and don’t listen to the teacher. You need to be aware that these short-term pleasures of movie, games, etc. won’t do any good to your career and if you waste this precious time, it would certainly affect your career. Make friends wisely so that they don’t have a bad influence on you. During my preparation time, I had very few friends and they were my competitors too who pushed me to work harder.

If you perform well, some people might be jealous of you and will try to bring down your performance. Be wary of such people and try to minimise your interaction with them, as these people would just bring negativity in your life, and you just cannot afford to think about such nuisance when you have a lot more important things to ponder upon.

Sometimes, some students might bring random questions and ask you. You might get frustrated on not being able to solve them. So it is advisable to only solve questions from books or the study material of you coaching institute. Once, a classmate of mine gave me a question on Integration, which was unsolvable (not all Integrals possess a solution). I spent about three hours on that question only to realize that the Integral was unsolvable, after I asked that question to my teacher. Then my teacher advised me to solve questions only from standard sources and not the ones given by any other person (except the teachers of course <img alt="

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Approx 11.99 lacs candidates appeared in JEE MAIN eXAM

Whereas 2.2 lacs candidates appeared in JEE Advanced 

Around 144086 candidates appeared in JEE Main paper 2

Check out JEE Main Paper 2 Cutoff

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