Respuesta :
The metals of fourth period are Arsenic, Germanium, Scandium and Xenon.
(a)
Fourth Period
Five valence electrons
Five valence electrons means: This is V A group element.
V A group elements are: N, P, As, Sb, Bi
N = 7: 1s² 2s² 2p³
P = valence configuration = 3s²3p³
As valence configuration = 4s²4p³
So, the metal is As (Arsenic).
(b)
Fourth Period
Two 4-p electrons
Four valence electrons means: This is IV A group element.
IV A group elements are: C, Si, Ge, Sn, Pb
C = 6: 1s² 2s² 2p²
Si = valence configuration = 3s²3p²
Ge valence configuration = 4s²4p²
So, the metal is Ge (Germanium).
(c)
Fourth Period + one 3d electron
It is d-block element.
Sc = 21: 1s² 2s² 2p⁶3s²3p⁶4s²3d¹
3d¹ (one 3d one electron)
4s² (indicates fourth period)
Hence, the metal is Sc (scandium).
(d)
Fifth period + complete outer-shell
Complete outer-shell elements = He, Ne, Ar, Kr, Xe, Rn
He = 2: 1s²
Ne = 10: 1s² 2s² 2p⁶
Ar outer-shell = 3s²3p⁶
Xe outer-shell = 5s²5p⁶
Hence the metal is Xenon (Xe).
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