  Stimulated by the exciting progress in the observation of new bottomonium
states, we study the bottomonium spectrum. To calculate the mass spectrum, we
adopt a nonrelativistic screened potential model. The radial Schr\"{o}dinger
equation is solved with the three-point difference central method, where the
spin-dependent potentials are dealt with non-perturbatively. With this
treatment, the corrections of the spin-dependent potentials to the wave
functions can be included successfully. Furthermore, we calculate the
electromagnetic transitions of the $nS$ ($n\leq 4$), $nP$ ($n\leq 3$), and $nD$
($n\leq 2$) bottomonium states with a nonrelativistic electromagnetic
transition operator widely applied to meson photoproduction reactions. Our
predicted masses, hyperfine and fine splittings, electromagnetic transition
widths and branching ratios of the bottomonium states are in good agreement
with the available experimental data. Especially, the EM transitions of
$\Upsilon(3S)\to \chi_{b1,2}(1P)\gamma$, which were not well understood in
previous studies, can be reasonably explained by considering the corrections of
the spin-dependent interactions to the wave functions. We also discuss the
observations of the missing bottomonium states by using radiative transitions.
Some important radiative decay chains involving the missing bottomonium states
are suggested to be observed. We hope our study can provide some useful
references to observe and measure the properties of bottomonium mesons in
forthcoming experiments.
