第18章典型元素の金属・半金属・非金属

The alkali metals all have a single s electron in their outermost shell. In contrast, the alkaline earth metals have a completed s subshell in their outermost shell. In general, the alkali metals react faster and are more reactive than the corresponding alkaline earth metals in the same period.

$\begin{array}{l}\text{Na}+{\text{I}}_2⟶\text{2NaI}\\ \text{2Na}+\text{Se}⟶{\text{Na}}_2\text{Se}\\ \text{2Na}+{\text{O}}_2⟶{\text{Na}}_2{\text{O}}_2\end{array}$
$\begin{array}{l}\text{Sr}+{\text{I}}_2⟶{\text{SrI}}_2\\ \text{Sr}+\text{Se}⟶\text{SrSe}\\ \text{2Sr}+{\text{O}}_2⟶\text{2SrO}\end{array}$
$\begin{array}{l}\text{2Al}+{\text{3I}}_2⟶{\text{2AlI}}_3\\ \text{2Al}+\text{3Se}⟶{\text{Al}}_2{\text{Se}}_3\\ \text{4Al}+{\text{3O}}_2⟶{\text{2Al}}_2{\text{O}}_3\end{array}$

The possible ways of distinguishing between the two include infrared spectroscopy by comparison of known compounds, a flame test that gives the characteristic yellow color for sodium (strontium has a red flame), or comparison of their solubilities in water. At 20 °C, NaCl dissolves to the extent of $\frac{\text{35.7 g}}{\text{100 mL}}$ compared with $\frac{\text{53.8 g}}{\text{100 mL}}$ for SrCl₂. Heating to 100 °C provides an easy test, since the solubility of NaCl is $\frac{\text{39.12 g}}{\text{100 mL}},$ but that of SrCl₂ is $\frac{\text{100.8 g}}{\text{100 mL}}.$ Density determination on a solid is sometimes difficult, but there is enough difference (2.165 g/mL NaCl and 3.052 g/mL SrCl₂) that this method would be viable and perhaps the easiest and least expensive test to perform.

(a) $\text{2Sr}(s)+{\text{O}}_2(g)⟶\text{2SrO}(s);$ (b) $\text{Sr}(s)+\text{2HBr}(g)⟶{\text{SrBr}}_2(s)+{\text{H}}_2(g);$ (c) $\text{Sr}(s)+{\text{H}}_2(g)⟶{\text{SrH}}_2(s);$ (d) $\text{6Sr}(s)+{\text{P}}_4(s)⟶{\text{2Sr}}_3{\text{P}}_2(s);$ (e) $\text{Sr}(s)+{\text{2H}}_2\text{O}(l)⟶\text{Sr}{(\text{OH})}_2(aq)+{\text{H}}_2(g)$

11 lb

Yes, tin reacts with hydrochloric acid to produce hydrogen gas.

In PbCl₂, the bonding is ionic, as indicated by its melting point of 501 °C. In PbCl₄, the bonding is covalent, as evidenced by it being an unstable liquid at room temperature.