system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are metals with low melting points (eg mercury and lead) more poisons or harmful?
gpt
They're unrelated. Gallium, indium, bismuth, sodium, potassium, rubidium and caesium are all metals with low melting points that aren't particularly toxic. 

Gallium melts slightly above room temperature. You could have it melt into a puddle in your hand and suffer no ill effects.

Indium is a soft metal that melts below 200 C. It's not particularly toxic.

Bismuth has a melting point below that of lead. It's non-toxic to the point that pepto bismol's active ingredient contains bismuth.

Sodium and potassium have melting points below that of boiling water and both are essential to life.

Rubidium and caesium are not very toxic. The toxicity of their compounds is comparable to table salt.