“Hey friends! Shantanu is back and this time with a useful guide on Chemistry.”
Guys, it is an obvious thing that Chemistry in class 9th seems Rocket Science! When I reached at this standard, I scared from it!! But finally(as the session is over), I have been able to prepare some important notes regarding Elements, Compounds, Ions, etc. and now it seems easy!
Want to now how? Then follow this article…
Don’t take Chemistry as burden
Get yourself a fresh notebook with good capacity for noting down and practicing. The main thing is that firstly gather confidence to at least grace your Chemistry book. Cordova and other better publications(better than NCERT) have claimed best guides and help books for this subject. Schools may provide them or you may use them in the library and issue them for some weeks. The best way is to buy it read them online! These books give detailed information for each point to be covered, and some extra information for which CBSE throw questions upon in exams; most of such information is not even informed by NCERT for their presence as syllabus!
Give at least Half an hour daily or 1 hour if it is your only weakness and study the concepts deeply during that time. This will encourage you to consider the so-called hard subject, easy.
Study definitions, descriptions and theory of each topic under ‘Element’, ‘Compound’, ‘Ion’, ‘Configurations’, etc.
You must put down the strong points of every topic and subtopic covered under the basics of Chemistry of this standard(mentioned above) in your practice copy/notebook:
- Make flow charts for hierarchial data.
- Underline the main lines and words from the book and understand them to be able to compress them meaningfully and note down.
- Mention and learn the main features of every model, such as Neil Bohr’s, Rutherford’s(experiment), etc. models.
- Also mention possible examples with the written entries*
Relations between Atomic number, Atomic mass, Avogadro’s number, Electronic configuration, etc.- the basics of every Reaction
This is the main thing to memorise and remember forever; but never take pains in mugging up the atomic number of every element. There are a few things which may help you, just like they helped me!
- Atomic number(number of protons/electrons) is always half of the atomic mass/Mass number(when the Mass number is an even number) or 0.5 less than half of the Mass number(when the Mass number is an odd number); note that the number of subatomic particles of an atom has to be a whole number.
- Since Mass number is the sum of Atomic number and the number of neutrons, the number of neutrons can be calculated by subtracting the Atomic number from the Mass number. The number of neutrons can be greater than Atomic number.
- Hence, when an element is given with its Mass number(exact Mass number), we can calculate it’s Atomic number(and thus the number of electrons, since Atomic number=number if electrons, for a non-ionic element) and find out is valency. This can be done keeping in mind that the first energy shell(K shell) can have 2 electrons and the next shells can have 8 electrons maximum; simply distribute the electrons among shells according to this and then,
if, the last shell has less than 4 electrons, valency is the number of electrons in the last shell and it is a metal,
the last shell has more than 4 but less than 8 electrons, valency is 8-(number of elections in the last shell) and it is a non-metal,
the last shell has exactly 4 electrons, valency is 4 and it is a metalloid or semi-conductor(exception: Carbon), and
if, the last shell had exactly 8 electrons, then the element is stable(because the octet is complete) without any valency and is thus, a noble gas.
Keep the electronic configurations, valencies, Atomic numbers and masses of common elements in hand to reduce time…
“I hope this article will help you. Never hear from Chemistry and also don’t think the higher Chemistry tough, because they become easier when you study more deeply and carry these simple tips on your fingertips!!”
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