In aqueous solution the water molecules directly attached to the metal ion are said to belong to the first coordination sphere, also known as the first, or primary, solvation shell.
ɪn ˈeɪkwɪəs səlˈuːʃən ðə wˈɔːɾɚ mˈɑːlɪkjˌuːlz dᵻɹˈɛktli ɐtˈætʃt tə ðə mˈɛɾəl ˈaɪɑːn ɑːɹ sˈɛd tə bᵻlˈɔŋ tə ðə fˈɜːst koʊˈɔːɹdᵻnˈeɪʃən sfˈɪɹ, ˈɔːlsoʊ nˈoʊn æz ðə fˈɜːst, ɔːɹ pɹˈaɪmɚɹi, səlvˈeɪʃən ʃˈɛl.