Unit 22.Atomic physics

04.19.2020
09:34:42
Dear students, good morning
Today's topic : elements and isotopes
Pg.no 313 to 314
The important points are
1 .proton number ( Z ) says which element an atom belongs to
For example
* If Z = 2 it's a helium ( He ) atom
* If Z = 92 it's a Uranium ( U ) atom
2. Proton number + neutron number = nucleon number
Z + N = A
3. Isotope :
The atoms of all elements exist in more
than one form
For example:
* There are 3 types of hydrogen atom .
* Each has just one protons in its nucleus, but they have different number of neutrons ( 0 , 1 ,2)
It's called as different isotopes of hydrogen look at table 22.2
4. For most chemical elements , atleast one isotope is stable , other isotopes may be unstable
5.it means that they undergo radioactive decay, emitting radiation as they change from one element to another
For better understanding of concepts watch the below videos