I have a science exam ... tomorrow, lol, so have started revising this moring.
Writing notes though, to memorize I am confused at the differences between four chesmisty terms which I dont think has enough to identify them as difference tihngs. Heres the terms and the definition I have for it:
Molecule: Smallest unit of an element composed of two or more atoms helded together my chemical force.
Element: Substance composed of atoms having an identical number of protons in each nucleus.
Atom: Smallest unit of an element having all the properties of it, positively charged nucleus surround by a system of electrons.
Compound: Substance formed by a reaction of two or more elements joining in proportion of weight.
I know about the atom structure, but have looked around many sites, used google for definitions and more but cant seem to find an explanation, mainly to help me understand what a molecule and compound is, maybe someone who does science in college or university or even someone also doing gcses can help makes the terms clearer for me.
For example, what does it mean by saying proportion of weight in the compound definition? ... that elements of the same mass joining? ...
Thanks for any help.