What is the difference between compounds,elements and atoms?

element is kind of same thing as atom. Let's take the element silver for example- silver has millions of atom in it because atom is small. so a element is something that has atom's. Atom looks like a circle. Atom has 3 things inside protons, neutrons and electrons. protons and neutrons have all of the mass and are bonded together while the electron move around in an atom.
A coumpound is when two elements on the periodic table combine together to form something.
Ex. when silver and carbon bonds together they form steel.

Atoms are the smallest bits of matter. Elements are the different types of atoms that exist. Examples of elements are oxygen nitrogen iron and so on. Compounds are when you combine two or more atoms to create a new material. Examples of compounds are water, plastics, rust  and just about everything you see around you.

Atoms aren't really the "smallest bits of matter".  Much matter is smaller than an atom...it is just that the most common matter of your surroundings takes the form of some kind of atoms or another.

General analogy (of course there are a few counterexamples):
Elements are to atoms as compounds are to molecules


Elements are the type of pure substances "standing alone" as atoms of the one kind.  They might be in same-atom molecular combinations, as Oxygen is...and that still is called an element.

Compounds are the type of pure substances combining several elements (or if only one element it must be a less ordinary form of it...like ozone is a compound despite only containing oxygen atoms).

Compounds in general, their smallest unit is the molecule.  A chemically bonded set of atoms, most likely of numerous different types of atoms.



By "pure substance", I mean that there isn't any physical mixing of any substances going on.  I.e. it is either an element or a chemically combined compound.

Solutions, blends, mixtures, alloys, etcetera aren't pure substances.

Atom is the smallest represetative particle of an element.   Element is a chemical matter that consists of only one type of atoms.
Let us have an example.   Hydrogen gas is an element.  Thus the hydrogen gas is made up of only one type atoms, and these are called hydorgen atoms.  
Similarly Oxygen gas is an element.  It is made up of only type of atoms namely oxygen atoms.

A compound is a chemical substance formed by the chemical reaction between the atoms of two or more elements.
For example Water is a compound.   Water is formed by the chemical reaction between the two elements -  Hydrogen and Oxygen.  
In the nature most of the elements exist as molecules.  Compounds will always have molecules.  Molecules are the chemical entities that have existance for a considerable time.

Thus hydrogen gas, an element naturaly exists as molecules.  Each hydrogen molecule is formed by the combination of two hydrogen atoms.
Similarly Oxygen also exists naturaly in the form of molecules.  Each oxygen molecule is formed by the combination of two oxygen atoms.

Water, which is a compound also consists of molecules.  Each water molecule is formed by the chemical combination of two atoms of hydrogen and one atom of oxygen.

The chemical reaction that leads to the formation water may be written as  

2 H2  +  O2   --->    2H2O