To determine which element forms a compound with hydrogen that has a chemical formula most and least similar to the chemical formula of the compound formed by hydrogen and phosphorus (PH3), we need to compare the chemical formulas of the compounds formed by phosphorus, nitrogen, selenium, oxygen, and rubidium with hydrogen.
Let's look at each compound's formula with hydrogen:
1. Phosphorus: Forms PH3 (phosphine)
2. Nitrogen: Forms NH3 (ammonia)
3. Selenium: Forms H2Se (hydroselenic acid)
4. Oxygen: Forms H2O (water)
5. Rubidium: Forms RbH (rubidium hydride)
### Step-by-Step Comparison:
1. Most Similar to Phosphorus (PH3):
- Nitrogen (NH3): Nitrogen is in the same group (Group 15) as phosphorus in the periodic table, so it forms a compound with hydrogen following the similar formula and valence, which is NH3. This is structurally the most similar to PH3, both being simple compounds with three hydrogen atoms bonded to a group 15 element.
- Selenium (H2Se): Selenium forms H2Se, which has only two hydrogen atoms bonded to selenium, differing in formula and bonding compared to PH3.
- Oxygen (H2O): Oxygen forms H2O, which also has two hydrogen atoms bonded, differing significantly from the PH3 structure.
- Rubidium (RbH): Rubidium forms RbH, which has a 1:1 ratio of rubidium to hydrogen, quite different from PH3.
Therefore, the most similar compound to PH3 is formed by Nitrogen (NH3).
2. Least Similar to Phosphorus (PH3):
- Nitrogen (NH3): As discussed, NH3 is the most similar.
- Selenium (H2Se): H2Se has two hydrogen atoms but still maintains a molecular similarity in that it's a group 16 element.
- Oxygen (H2O): H2O is also a group 16 element, having two hydrogen atoms.
- Rubidium (RbH): RbH has a completely different chemistry as an alkali metal hydride (group 1), with only one hydrogen atom bonded. This makes it structurally and chemically very different from PH3.
Therefore, the least similar compound is formed by Rubidium (RbH).
Based on these comparisons, the most similar compound to PH3 is Nitrogen (NH3), and the least similar is Rubidium (RbH).
In the table:
\begin{tabular}{|l|c|c|c|c|}
\cline { 2 - 5 }
\multicolumn{1}{c|}{} & nitrogen & selenium & oxygen & rubidium \\
\hline
most similar to phosphorus & [tex]$\checkmark$[/tex] & 0 & 0 & 0 \\
\hline
least similar to phosphorus & 0 & 0 & 0 & [tex]$\checkmark$[/tex] \\
\hline
\end{tabular}
