  The exceptional group $G_2$, when constructed over $Q_p$, may at the same
time be considered as the group of automorphisms of an octonion algebra over
$Q_p$, or alternatively it may be constructed as a Chevalley group from the
root diagram of the appropriate Lie algebra, $g_2$. Each construction has its
benefits and drawbacks, and the first part of this work focuses on drawing
parallels between the two and describing certain group structures in terms of
both. In particular, we explicitly identify the Chevalley generators of $G_2$
as automorphisms of octonions.
  In the second part of this work we describe the standard (affine) apartment
of the Bruhat-Tits building of $G_2$, constructing it from the coroot diagram
of the Lie algebra $g_2$. Previous work of W.T. Gan and J.K. Yu (2003)
describes this Bruhat-Tits building, alternatively, in terms of certain
"maximinorante norms" and lattices in the octonion algebra. Using our work from
Part One, we describe these norms and lattices in detail, which allows us to
act on our lattices using explicit octonion automorphisms and draw a very
complete picture of the standard apartment.
