Question

1. list the elements below in order of decreasing atomic radius. (biggest to smallest). li, be, f, k, c mg, be, sr, b, ne mn, as, kr, ra, v 3. are the elements below in order of increasing atomic radius? if yes, write \yes\. if not, write them in the correct order. tc, mo, ag, rb, xe cs, fr, h, he, na y, fe, sc, ga, se b, al, ga, in ti, k, ca, v o, s, se, te na, fr, cs, f hg, ti, pb, bi rn, bi, w, ba 4. briefly explain why atomic radius changes down groups. 5. briefly explain why atomic radius changes across periods

Explanation:

Atomic radius decreases across a period due to increasing nuclear charge (more protons) attracting electrons more strongly. Down a group, atomic radius increases as there are more electron shells, increasing the distance from the nucleus. For the elements in question, applying these trends:

• For \(Li, Be, F, K, C\) vs \(Mg, Be, Sr, B, Ne\) vs \(Mn, As, Kr, Ra, V\):
• In a period (left - to - right), radius decreases. In a group (top - to - bottom), radius increases.
• \(Ra>Mn>V>As>Kr\) (as \(Ra\) is in a lower period with more shells; \(Mn, V\) are transition metals, \(As\) is a p - block, \(Kr\) is a noble gas in the same period as \(As\) but with a full shell, slightly larger due to electron - electron repulsion but still smaller than the others as it's further right in the period).
• \(Mg>Sr>Be>B>Ne\) (incorrect as \(Sr\) (period 5) should be larger than \(Mg\) (period 3). Correct order considering periods and groups: \(Sr>Mg>Be>B>Ne\) (but original elements: for \(Li, Be, F, K, C\) - \(K\) (period 4) is larger than \(Li\) (period 2), \(Li\) larger than \(Be\) (same period, \(Be\) further right), \(C\) (same period as \(Be\), further right, smaller), \(F\) (same period as \(C\), further right, smaller. But overall for the full set of elements in question 2:
• Using the rules: atomic radius decreases across a period (left - to - right) as effective nuclear charge increases (more protons pull electrons closer). In a group (top - to - bottom), radius increases as electron shells are added.

Answer:

\(Ra > Mn > V > As > Kr\); \(Sr>Mg>Be>B>Ne\); \(K > Li > Be > C > F\) (for the relevant subsets in question 2, applying the atomic radius trends across periods (decreasing left - to - right) and down groups (increasing top - to - bottom))