Pure substances can be elements or compounds. An element is a form of matter that cannot be broken down by chemical reactions into simpler substances. A compound is a substance composed of two or more different types of elements ,chemically combined in a fixed ratio. 2.(a) Elements and compounds are called as pure substances because it is made up of  * a. same kind of atoms or molecules
b. different kinds of atoms or molecules
c. heterogeneous mixtures
d. solutions​

Write the symbol for every chemical element that has atomic number greater than 3 and atomic mass less than 12.0 u.

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.

What will most likely happen when two bromine atoms bond together?