The coinage metals' filled d shell is much more easily disrupted than the alkali metals' filled p shell, so that the second and third ionisation energies are lower, enabling higher oxidation states than +1 and a richer coordination chemistry, thus giving the group 11 metals clear transition metal character.
ðə kˈɔɪnɪdʒ mˈɛɾəlz fˈɪld dˈiː ʃˈɛl ɪz mˈʌtʃ mˈoːɹ ˈiːzili dɪsɹˈʌptᵻd ðɐn ðɪ ˈælkəlˌaɪ mˈɛɾəlz fˈɪld pˈiː ʃˈɛl, sˌoʊ ðætðə sˈɛkənd ænd θˈɜːd ˌaɪənəzˈeɪʃən ˈɛnɚdʒiz ɑːɹ lˈoʊɚ, ɛnˈeɪblɪŋ hˈaɪɚɹ ˌɑːksɪdˈeɪʃən stˈeɪts ðɐn plˈʌs wˈʌn ænd ɐ ɹˈɪtʃɚ koʊˈɔːɹdᵻnˈeɪʃən kˈɛmɪstɹi, ðˈʌs ɡˈɪvɪŋ ðə ɡɹˈuːp ɪlˈɛvən mˈɛɾəlz klˈɪɹ tɹænsˈɪʃən mˈɛɾəl kˈæɹɪktɚ.