1. STRUCTURE OF ATOM AND NUCLEUS
HOW MANY ELECTRONS CAN BE IN A SHELL?
HOW ARE THE SHELLS NAMED?

2. WHAT IS MEANT BY ATOMIC NUMBER AND MASS NUMBER?
ATOMIC NUMBER IS NUMBER OF PROTONS – SYMBOL IS ‘A’
MASS NUMBER IS NUMBER OF PROTONS AND NEUTRONS – ‘Z’
WHAT IS MEANT BY NUCLEONS?

3. IF ATOM UNDERGOES A
CHEMICAL CHANGE
– THERE IS A CHANGE IN NUMBER OF ELECTRONS IN THE ATOM
- ENERGY IS FEW ELECTRON VOLTS
NUCLEAR CHANGE
– THERE IS A CHANGE IN THE NUMBER OF NUCLEONS INSIDE THE NUCLEUS OF AN ATOM
- ENERGY IS FEW MEGA OR MILLION ELECTRON VOLTS (MeV)

4. ISOTOPES ISOBARS ISOTONES
ATOMS OF THE SAME ELEMENT
ATOMS OF THE DIFFERENT ELEMENTS
ATOMS HAVING
same atomic number Z
different mass number A
same mass number A
different atomic number Z
different number of protons
same number of neutrons
WHAT ARE THE TWO KINDS OF ISOTOPES?
WHAT HAPPENS WHEN NUMBER OF NEUTRONS EXCEED THE NUMBER OF PROTONS?