Question

periodic table high school reference sheet
the elements k, ca, se, kr, and ga - all appear in period 4 of the periodic table. arrange them in order of their atomic size, from largest to smallest.
se kr k ga ca

Explanation:

Step1: Understand atomic size trend in a period

In a period (horizontal row) of the periodic table, atomic size (atomic radius) decreases from left to right. This is because as we move from left to right, the number of protons in the nucleus increases (increasing the positive charge), and electrons are added to the same energy level. The increased nuclear charge pulls the electrons closer to the nucleus.

Step2: Locate the elements in Period 4

The order of the elements \(K\), \(Ca\), \(Ga\), \(Se\), \(Kr\) from left to right in Period 4 is \(K\) (Group 1), \(Ca\) (Group 2), \(Ga\) (Group 13), \(Se\) (Group 16), \(Kr\) (Group 18).

Answer:

\(K>Ca > Ga>Se > Kr\)