Here let's discuss the difference between atoms, elements,compounds and mixtures. First let's discuss element. Element is the basic substance that can't be simplified and it consists of only one kind of atom. Element cannot be broken down into a simpler type of matter by either physical or chemical means. Notice that element can exist as either atoms like Fe (iron atom) or molecules, for example N2 (nitrogen molecule). Now go back to atom. Atom is the smallest amount of an element. Just like what we mention, Fe (iron atom), K (potassium atom). Moleculeis two or more atoms that are chemically joined together. For example, N2 (nitrogen molecule), Cl2 (chlorine molecule).
Now let's talk about compounds. A compound consists of atoms of two or more different elements bound together,and can be broken down into a simpler type of matter by chemical means but not by physical means. Compound has properties that are different from its component elements, and always contains the same ratio of its component atoms. For example, H2O water molecule is consisting of H (hydrogen) and O (oxygen) atoms in 2:1 ratio, and H2O has properties that are different from its component elements H and O, like water is liquid in room temperature while hydrogen and oxygen are gas under room temperature.
Last but not the least let's talk about mixture. Mixture consists of two or more different elements and / or compounds PHYSICALLY intermingled,can be separated into its components by PHYSICAL means, and often has the properties of its components. Notice that I capitalize PHYSICAL and PHYSICALLY, because mixture is not about chemical reactions, it's just physical! For example you mix apple juice with orange juice, then that is a mixture. and it has the properties of its components, it will taste like apple juice and orange juice at the same time. It's not easy to sperature them but possible, so this is not a perfect example here. Another better example is sand and magnitized powders. You mix them and you have a mixture. But you can seperature them physically using a magnet.