Electrons!! :D
When atoms combine interactions occur between their electrons. In most cases they will share or give electrons to the other atoms.
That's because of the way "compound" is defined. If atoms of an element combine with other atoms of the SAME element, then it's not called a "compound".
Interactions occur between their eletrospheres, where their valence electrons are located.
not necessarily. A molecule is multiple atoms combined chemically, but the atoms do not need to be of different elements. A compound is several elements combined chemically though.
The interactions of its atoms with light.
The subscript 2, combined with the fact that the symbol for carbon atoms does not occur anywhere else in the formula, means that each molecule of ethyl alcohol contains two carbon atoms.
molecule
The interactions of its atoms with light.
helium atoms
ecosystem
ecosystem
helium atoms