The energy gap, $\Delta E$, for silicon is $110 \mathrm{~kJ} / \mathrm{mol}$. What is the minimum wavelength of light that can promote an electron from the valence band to the conduction band in silicon? In what region of the electromagnetic spectrum is this light?

The effect of temperature change on the electrical conductivity of ultrapure silicon is quite different from that on silicon containing a minute trace of arsenic. Why is this so?

Explain whether the addition of gallium arsenide in trace amounts to germanium, would produce a $n$-type semiconductor.

Explain whether the addition of arsenic in trace amounts to germanium, would produce a $n$-type semiconductor.

Explain whether the addition of cadmium sulfide in trace amounts to germanium, would produce a $n$-type semiconductor.

Explain whether the addition of tin in trace amounts to germanium, would produce a $n$-type semiconductor.

A reaction involved in the formation of ozone in the upper atmosphere is $\mathrm{O}_2 \longrightarrow 2 \mathrm{O}$. Without referring to Table 10.3, indicate whether this reaction is endothermic or exothermic. Explain.

Explain whether the addition of aluminium in trace amounts to germanium, would produce a $n$-type semiconductor.

Explain whether the addition of sulfur in trace amounts to germanium, would produce a $n$-type semiconductor.

Explain whether the addition of gallium in trace amounts to silicon, would produce a $p$-type semiconductor.

Explain whether the addition of gallium arsenide in trace amounts to silicon, would produce a $p$-type semiconductor.

Assuming that the seventh period is 32 members long, what should be the atomic number of the noble gas following radon (Rn)? Of the alkali metal following francium (Fr)? What would you expect their approximate atomic masses to be?

Explain whether the addition of boron in trace amounts to silicon, would produce a $p$-type semiconductor.

Explain whether the addition of lead in trace amounts to silicon, would produce a $p$-type semiconductor.