Metal-Metal bondin is more extensive in the 4d and 5d series of transition elements than the 3d series. Explain.

Explanation

Down the group in the transition metals, the atomic sizes increases. Therefore, electrons in element belonging to 4d and 5d series are less loosly held by the nucleus as compared to the elements present in the 3d series but in the same group. The metal-metal bonding is more extensive or stronger. In other words, the metallic character increases down the group.