Question

what name is given to materials made of same kind of element

Answer 1

Well - today's industry can produce virtually any element at any degree of purity. So I guess it's more accurate to talk about the substances that occur naturally.

On a separate note, Anthony Pun did a great job here explaining allotropes.

So, I'll try to answer the following question - what substances composed of single kind of atoms do occur naturally on earth and are fairly stable under normal conditions?

This wiki article provides good info -

Here's the list -

Gold, silver, platinum, copper - occur naturally as nuggets

Carbon - diamond, graphite, charcoal left from wood fires.

Sulfur - condensed from volcanic fumes

Silicon and a number of metals - see the link above - found in pure form much less commonly.