Atomic Structure
Chemistry · परमाणु संरचना · 15 facts
Atom: smallest particle of element in chemical reaction; Greek atomos=indivisible
Dalton Atomic Theory(1808): atoms indivisible, same element=identical atoms
Thomson: electron discovered(1897); Plum Pudding Model
Rutherford: nucleus+proton(1911); Gold Foil experiment; atom mostly empty
Chadwick: neutron discovered(1932); neutral particle in nucleus
Proton: +ve, mass=1amu, nucleus; Electron: -ve, negligible mass, orbits
Neutron: neutral, mass=1amu, in nucleus; provides stability
Atomic number(Z) = protons = electrons (neutral atom)
Mass number(A) = protons + neutrons
Isotopes: same Z different A; H-1, Deuterium(H-2), Tritium(H-3)
Isobars: same A different Z; C-14 and N-14
Bohr Model(1913): electrons in fixed shells K,L,M,N
Max electrons in shell = 2n2 (K=2, L=8, M=18, N=32)
Valence electrons: outermost shell; determine chemical properties
Valency: combining capacity; Na=1, Mg=2, Al=3, C=4