## Chemistry and Chemical Reactivity (9th Edition)

Per atom: $68000\ J/mol\div 6.022\times10^{23}\ atom/mol=1.13\times10^{-19}\ J/atom$ $E=h.\nu=h.c/\lambda$ $1.13\times10^{-19}\ J=6.626\times 10^{-34}\ J.s\times 2.998\times 10^8\ m/s\div \lambda$ $\lambda=1.76\times10^{-6}\ m=1760\ nm$