Question

Use Slater's rules to estimate Zeff for the chromium, manganese, iron and cobalt atom

Answer 1

i chromium: & Electronic Configuration of chromium according to filling is 15²825²286 35 3po us² 3d" Arrange these shells according to the in' value because they are arranged similar manner in atom. closest to farthest. 1822822p635²3p63d" 48² I Group 182 sep orbital, ob similar in 28²286 35 36 3.4 ust. wers need Zelf for a orbital so, multiply 0.35 to the same shell electrons and 1 to the preceding dectrons. 3- s°эр эсэ 6 ° us - 2x18x18x13x0.35 = 19.05 do. A protons in chromium - au Zelf = 2u - 19.05 = 4.95 The è in 3d experience only 4.95 protone 'change

In the similar way Manganes Iron – 5.6 - 6.25 Zest of Zeff oder Zeff of = 6.9 Cobalt

Zeff is the amount of positive charge(pull) experienced by electrons. Though 24 protons are present in chromium last electron doesnt experience total charge due to shielding by initial electrons. Thus 4S is filled first than 3d 4s electrons are not considered because they are present after 3d in the position in the atom thus 4s electrons shielding is not considered.