So the answer is: 3; 1s 222 p 63s 23 p 63d 10;
(2) In the complex ion [Cu(NH3)4(H2O)2]2+, there is a coordination bond between N and Cu, and the N-H and O-H bonds are polar bonds; The more nonmetallic an element is, the more electronegative it is. If nonmetal: O>N>H, electronegativity O > N > H, the order of N and O is O > N > H,
Therefore, the answer is: coordination bond, polar valence bond; o > N > H;
(3) According to the picture of EDTA structure, it can be seen that carbon atoms exist in the form of single bond and double bond, the valence electron logarithm of carbon atoms is 4 when carbon atoms exist in the form of single bond, and the hybridization mode is sp3, and the valence electron logarithm of carbon atoms is 3 when carbon atoms exist in the form of double bond, and the hybridization mode is sp2.
So the answer is: sp3, sp2;;
(4) From the unit cell of CuCl, it can be judged that the distance between each copper atom and four Cl is the closest and equal, that is, the coordination number of Cu is 4, and according to the chemical formula, the coordination number of Cl is also 4.
So the answer is: 4.