An element is a substance that cannot be broken down by chemical means. Elements are extremely particular compounds that serve as the foundation for all life and matter (well other than the stuff smaller than atoms). It can contain one atom or trillions of them for anything to be an element, however atoms of different types cannot be combined in. That is to say, every atom has a set number of protons, ranging from 1 to 118. You can be positive that the substance you have is hydrogen if there is just one proton present. Mercury is what you get if you have 80 protons. Atoms of pure hydrogen only contain one proton. As most people are aware, if you add oxygen to it, it turns into water, which is no longer an element but a compound. Nevertheless, the building blocks are the elements. Every single object you can see is composed of elements, whether there are many of them, as there are in the human body, or only a few, as there are in salt.
A compound is a substance with a definite composition (with some leeway there, there are 'non-stoichiometric' compounds), that is composed of 2 or more elements.
Further explanation:
A compound in chemistry is a material that is created by mixing two or more distinct chemical elements in such a way that the atoms of the various elements are kept together by strong chemical bonds. These bonds form as a result of the sharing or exchange of electron s among the atoms. A molecule is the smallest, unbreakable unit of a substance.
A mixture is not a compound since there is no bonding between the atoms of the constituent substances in a mixture. In certain cases, mixing dissimilar elements causes chemical reactions that result in the formation of bonds between the atoms and the molecules of a compound. Other possibilities allow mixing distinct components without causing a reaction, preserving the separate identities of the elements. When elements are combined, reactions can happen quickly or slowly (for example, when iron is exposed to oxygen) (as when lithium is exposed to oxygen). There are times when an element is introduced to a chemical, a reaction takes place, creating new compounds (as when pure elemental sodium is immersed in liquid water).
A compound frequently looks and acts quite different from any of the constituent parts. Think about hydrogen (H) and oxygen, for instance (O). At standard atmospheric pressure and room temperature, both of these substances are gases. However, they combine to form the well-known material known as water, which is a liquid at room temperature and at normal atmospheric pressure and whose molecules each contain two hydrogen atoms and one oxygen atom (H2O).
Few elements' atoms readily combine with those of other elements to produce compounds. These gases—helium, neon, argon, krypton, xenon, and radon—are referred to as noble or inert gases. Compounds made of certain elements can be formed easily with other elements. Examples include fluorine, chlorine, and oxygen.
2) The adjective compound refers to something that is made up of several different components. Examples of this usage include compound eyes, which are found in a variety of insects, compound microscopes, which are high-power magnifying devices made up of multiple lenses, compound sentences, which are organized collections of smaller sentences that form a single integrated perceptual environment, and compound documents.