Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 9 Answered

Give Reason. Two electrons in helium are placed in only one shell while three electrons in Lithium occupy two shells.
Asked by shreyas yedekar | 11 Aug, 2010, 04:41: PM
answered-by-expert Expert Answer
1) first shell can have a max of two electrons only n = 1 , So, 2n2 = 2
2) Helium has 2 electrons so they can be accomodated in the first shell itself. Lithium has three electrons. So, once the first shell is filled completely by two electrons, the third electron goes to the 2nd shell.
Answered by | 12 Aug, 2010, 11:05: AM

Application Videos

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
CBSE 9 - Chemistry
what is atom
Asked by rajputanaji290 | 03 Oct, 2023, 09:30: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
(B) An element X has 17 protons and 18 electrons. (a) what is the valency of X? (b) find the number of neutrons in X? (c) What is the mass number of X?
Asked by muditsharma287 | 09 Mar, 2023, 10:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
how is protons mass when compared to electron
Asked by shivalaxmi0205 | 08 Mar, 2023, 07:46: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
what is the Mass of electron
Asked by shivalaxmi0205 | 08 Mar, 2023, 07:43: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
Why hydrogen atom does not have neutrons
Asked by jssjj | 19 Jan, 2023, 07:25: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
  name and write the formula of atleast 20 elements of everyday use   
Asked by mohammedhaqqani.6b | 14 Jun, 2022, 02:51: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
how many moles in an atom
Asked by gauravsingh36428 | 14 Mar, 2022, 07:44: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
the ratio by mass of nitrogen and hydrogen in ammonia is 14:3 . calculate the ratio by number of atoms of elements in ammonia molecule .
Asked by jiyajthakor | 28 Feb, 2022, 07:03: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
Assertion reason (A) phosphate ion is a polyatomic anion (R) in phosphate anion 5 atoms are present   
Asked by gillsaabjashanpreetsingh3 | 16 Jan, 2022, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 9 - Chemistry
calculate the formula unit mass of CaCl2
Asked by prachisharma772007 | 16 Jan, 2022, 11:12: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Get Latest Study Material for Academic year 24-25 Click here
×