Question

1. the following chart lists elements atomic radii in the periodic tables first column. provided that potassium follows the same pattern as the other elements, what is the atomic radius of potassium? h 25 li 145 na 180 k? rb 235 cs 260

Explanation:

Step1: Analyze the pattern of atomic radii increase

Looking at the given data: From \(H\) (\(25\)) to \(Li\) (\(145\)) the increase is \(145 - 25=120\). From \(Li\) (\(145\)) to \(Na\) (\(180\)) the increase is \(180 - 145 = 35\). From \(Na\) (\(180\)) to \(Rb\) (\(235\)) (skipping \(K\) for now), if we assume a more regular pattern considering the general trend of atomic radius increasing down a group in the periodic table. Another way: Looking at the differences between consecutive known - non - hydrogen elements. The difference between \(Li(145)\) and \(Na(180)\) is \(35\). If we assume a similar incremental pattern (since the data is limited, but based on the fact that atomic radius increases down a group). The difference between \(Na(180)\) and \(Rb(235)\) is \(235 - 180=55\). But if we consider a more simple arithmetic - like progression (given the options). If we assume that the atomic radius of \(K\) follows a pattern where it is greater than \(Na\)'s atomic radius (\(180\)) and less than \(Rb\)'s atomic radius (\(235\)).

Step2: Check the options

Among the options \(190\), \(220\), \(250\), \(150\). Since \(150<180\) (violates the increasing down - the - group trend as \(K\) is below \(Na\) in the group), \(250>235\) ( \(K\) is above \(Rb\) in the group, so its atomic radius should be less than \(Rb\)'s), \(190\) is close to \(180\) but the increase from \(Na\) to \(Rb\) suggests a larger jump. The value \(220\) is greater than \(180\) (follows the down - the - group increase trend) and less than \(235\).

Answer:

\(220\)