$\begin{array}{1 1}\text{decreases,(i) from the left to right across a period and (ii) on descending a group}\\\text{decreases from left to right across a period and increases on descending a group}\\\text{increases from left to right across a period and decreases on descending a group}\\\text{increases,(i) from left to right across a period and (ii) on descending a group}\end{array} $
