Electronic Configurations & Oxidation States

Copper subgroup elements are d-elements of IV, V and VI periods that should possess d⁹ -electron сonfiguration, although the jump of ns- electron to (n-1)d- sublevel is more energetically favourable:

(n-1)d⁹ns² (n-1)d¹⁰ns¹.

These two states of atoms are close to one another by energy. Therefore, oxidation states +1,+2, and also +3 exist. The latter oxidation state appears when atoms loose 2s electrons and 1 unpaired d -electron.

The most typical oxidation states of Cu are +1, +2, Ag +1, and Au +1, +3 (the most stable are underlined).

The values of atomic radii of these elements are significantly smaller than that of alkali metals belonging to the same group. This fact explains extremely low chemical activity of noble metals of copper subgroup (some authors include only Ag and Au to the noble metals family). Especially low is the reactivity of gold that has equal size to the atom of silver (due to effect of lanthanide contraction) and contain 32 additional electrons simultaneously. The charge of atomic nucleus of gold is larger than silver as well as attraction forces of outermost shell electrons to its own nucleus.

The chemical activity is decreased in the series Cu– Ag — Au.

	Cu	Ag	Au
Rа, nm	0.123	0.144	0.144
radius Е^+, nm	0.096	0.116	0.137
	K	Rb	Cs
Rа, nm	0.236	0.248	0.268

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