Atoms Jaitob Fdk

Structure of atom

ATOM Atom is the smallest particle of an element which may or may not have an independent existence i.e. can take part in a chemical reaction or can exist in independent form. For Example The atoms of inert gases like helium, krypton etc. can exist in independent form.

Atom is made up of two parts Atom

NUCLEUS (PROTONS+NEUTRONS)

EXTRA NUCLEUS (ELECTRONS)

Atom parts

NUCLEUS The central heavy and positively charged part of an atom is called nucleus. Nucleus contains positively charged protons and chargeless neutrons. Total mass of nucleus is called Atomic mass Atomic mass(A)=mass of protons(P)+ mass of neutrons(N)

PROTONS 

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It is the positively charged sub-atomic part of an atom. The actual mass of a proton is 1.673x10-24 The number of protons in the nucleus of an atom is equivalent to the number of electrons revolving in the extra nucleus part. Atomic No. (Z)=No. of Protons(P)

NEUTRON Neutron is very small neutral sub-particle of an atom. It has no charge It is represented by n James Chadwick was the first scientist to discover it.

EXTRA NUCLEUS The outer part of the nucleus combines electrons. These revolve around the nucleus in different circular orbits called energy levels. The no. of electrons(e)=No. of protons(p)

Electron Electron is the smallest ,negatively charged, sub-atomic particle of he atom which has unit negative charge. Actual mass of an electron is 9.1x10-28 kg. The mass of an electron is very small, hence its mass is considered as negligible.

Energy levels of electrons 

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Electrons with lowest energy are placed to the nucleus in lower energy level. Electrons with highest energy are placed in higher energy level. Energy level names starting from nucleus are : K,L,M,N ect. Or 1,2,3,4 Maximum no. of electrons in energy level are :2N2 ,where N=no. of energy level. For example if energy level=2 then no. of electrons in 2 level are: 2 x (2)2=8 If electrons in energy level are more than 8 then electrons start filling from inner most shell.

Energy levels of electrons

Prepared by

Baltej Singh  Arvinder Singh Class 9th A 

Govt. H.S.N Sr. Sec. School Jaitu.(Distt. FDK) Computer Faculty:- Amita Chawla Parminder kaur

BIBILOGRAPHY 

Science book of class IX of PSEB

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Guided by Ashok Kumar Science teacher.