Cross word puzzle
Clues:
Down:
1. Helium Nuclei (Particle)
2. Positive Charge mass at the core of the atom
3. An atom whose valency is zero
4. One or two electrons in the outermost shell of atoms of elements are called as ______________ electrons.
5. 146C is used for carbon dating
6. Discovery of neutron
Across:
1. Electrons present in the outermost shell
2. This pair of atoms 4020Ca, 4018Al are ____
3. An atom that does not have neutron
4. Scattering of α particles in the gold foil experiment
