Atomic radius

Atomic radius changes only a little along the series and is almost constant from Cr to Cu. Two opposing factors are responsible:

• Decrease: effective nuclear charge rises and electrons are added, so attraction to the electrons increases (Sc → Cr).
• Increase: as 3d electrons increase, repulsion between them increases. The two effects nearly cancel, so radii are nearly constant — one reason these metals mix easily to make alloys (atoms of nearly equal size replace one another in the lattice).