Atomic number, Mass number, Relative atomic mass and Atomic mass unit

Atomic number, Mass number, Relative atomic mass and Atomic mass unit

• 1.
  ATOMIC NUMBER (Z) Example Atomicnumber of Hydrogen is Z=1 atomic number of an element is equal to the number of protons present in the nucleus of its atom 1 Preparedby:QaziAbdulGhafoorSST,Govt.Boys HighSchool#1,DGKhan03321764856
• 2.
  MASS NUMBER (A) Mass number is the sum of the number of protons and neutrons present in the nucleus of an atom 2 Preparedby:QaziAbdulGhafoorSST,Govt. BoysHighSchool#1,DGKhan 03321764856
• 3.
  EXAMPLE 1.1: How manynumber of protons and neutrons are there in an atom having A=238, when Z=92 Solution DATA: A=238, Z=92 Number of protons =? Number of neutrons =? Number of protons =92 Number of neutrons = A-Z = 238-92 = 146 3 Preparedby:QaziAbdulGhafoorSST,Govt. BoysHighSchool#1,DGKhan 03321764856
• 4.
  RELATIVE ATOMIC MASS The relative atomic mass of an element is the average mass of atoms of that element as compared to 1/12th (one twelfth) of the mass of one atom of carbon-12 isotope. 4 Preparedby:QaziAbdulGhafoorSST,Govt. BoysHighSchool#1,DGKhan 03321764856
• 5.
  RELATIVE ATOMIC MASS EXAMPLES 1. Na has Relative Atomic Mass = 23 amu  2. O has Relative Atomic Mass = 16 amu  3. N has Relative Atomic Mass = 14 amu The unit for Relative Atomic Mass is called Atomic Mass Unit Symbol is “amu” 1 amu = 1.66 X 10-24 g 5 Preparedby:QaziAbdulGhafoorSST,Govt. BoysHighSchool#1,DGKhan 03321764856