Final answer:
Elements are categorized based on reactivity, metallic character, and period number. Potassium is the most reactive, followed by platinum and neon. In terms of metallic character, cesium is the most metallic, lithium is less so, and nitrogen is the least. Polonium has the highest period number, followed by cobalt and beryllium.
Step-by-step explanation:
Reactivity and Metallic Character
When organizing elements by reactivity, looking at their positions in the periodic table is crucial. Starting with potassium (K), platinum (Pt), and neon (Ne), we must consider that alkali metals are highly reactive, noble gases have minimal reactivity, and transition metals fall somewhere in between. Potassium, being an alkali metal, is the most reactive, while neon, as a noble gas, is the least reactive, and platinum is moderately reactive but less so than potassium.
Most to Least Reactive: K > Pt > Ne
Metallic Character
For metallic character, cesium (Cs) is the most metallic alkali metal, lithium (Li) is also highly metallic but less so than cesium, and nitrogen (N) is a nonmetal with the least metallic character.
Least to Most Metallic: N > Li > Cs
Period Number
The period number indicates the row of the periodic table in which an element is located. Cobalt (Co), beryllium (Be), and polonium (Po) are elements found in different periods. Polonium, being in the sixth period, has the highest period number, followed by cobalt in the fourth period, and beryllium in the second period.
Highest to Lowest Period Number: Po > Co > Be