Elements and compounds are pure chemical substances found in nature. The difference between an element and a compound is that an element is a substance made of same type of atoms, whereas a compound is made of different elements in definite proportions. Examples of elements include iron, copper, hydrogen and oxygen. Examples of compounds include water (H2O) and salt (Sodium Chloride - NaCl). Elements are listed according to their atomic number on the Periodic Table. Among the 117 known elements, 94 are naturally occurring like carbon, oxygen, hydrogen etc. 22 are artificially produced having undergone radioactive changes. The reason for this is their instability due to which they undergo radioactive decay over a period of time giving rise to new elements during the process like Uranium, Thorium, Bismuth etc. Elements combine in fixed ratios and give rise to stable compounds due to chemical bonds that facilitate compound formation.
Elements are distinguished by their name, symbol, atomic number, melting point, boiling point, density and ionization energies. In the Periodic Table, elements are arranged according to their atomic number and they are grouped according to similar chemical properties and are depicted by their symbols.
Compounds are composed of different elements in a fixed proportion. For example, 1 atom of sodium (Na) combines with 1 atom of chlorine (Cl) to form one molecule of sodium chloride (NaCl) compound. The elements in a compound do not always retain their original properties and cannot be separated by physical means. The combining of elements is facilitated by their valency. Valency is defined as the number of hydrogen atoms required that can combine with an atom of the element forming the compound. Most compounds can exist as solids (low enough temperatures) and can be decomposed by the application of heat. Sometimes foreign elements are trapped inside crystal structure of compounds giving them a non homogeneous structure. Compounds are depicted by their chemical formula which follows the Hill system wherein carbon atoms are listed first, followed by hydrogen atoms after which elements are listed in alphabetical order. Visualizing the DifferencesThis picture shows the differences between elements and compounds at an atomic level. Elements have only 1 type of atoms; compounds have more than 1. Elements and compounds are both substances; they differ from mixtures where different substances mix together but not via atomic bonds. History of Elements and CompoundsElements were initially used as a reference to any state of matter like liquid, gas, air, solid etc. Indian, Japanese and Greek traditions refer to five elements namely, air, water, earth, fire and aether. Aristotle conceptualized a new fifth element called 'quintessence' - which apparently formed the heavens. As research continued, many eminent scientists paved way for the current understanding and description of elements. Among them, work of Robert Boyle, Antoine Lavoisier, Dmitri Mendeleev are particularly notable. Lavoisier was the first to make a list of chemical elements and Mendeleev was the first to arrange elements according to their atomic number in the Periodic Table. The most current definition of an element is awarded by the studies carried out by Henry Moseley which states that the atomic number of an atom is expressed physically by its nuclear charge. Before the 1800s the usage of term compound could also mean a mixture. It was in the 19th century that meaning of a compound could be distinguished from a mixture. Alchemists like Joseph Louis Proust, Dalton and Berthollet and their studies on various compounds have given modern chemistry the current definition of compound. Proust’s work demonstrated to the world of chemistry that compounds were made constant composition of respective elements. CAS NumberEvery chemical substance is identified by its unique numerical identifier – the CAS (chemical abstracts service) number. Hence every chemical compound and element has a CAS number. This makes database searches for elements and compounds more convenient. References
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In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation. Science is all about order. And, to keep things straight, you have tons of different terminology. Sometimes, such as in the case of molecules vs. compounds, it gets confusing. Here’s why. Compounds and molecules are related because all compounds are molecules. Easy enough. However, the difference between compound and molecule is not all molecules are compounds. Is your head spinning yet? To clear everything up, it’s important to break down molecule vs. compound into their basic definitions and look at their various parts. To understand molecules, it’s important to first clear up atoms. Atoms are these fun structures with electrons, neutrons, and protons in them. Electrons and protons have a negative and positive charge respectively. Atoms like to be balanced. Therefore, they will chemically bond with other atoms to be balanced. When an atom bonds with other atoms, either the same type (O2) or a different type (H2O), it’s called a molecule. Molecules are tiny so you can’t see them with the naked eye. However, scientists can break them down to their atomic parts. For example, water is made of two hydrogen atoms and one oxygen atom (H2O). There are lots of different molecules. Here are just a few examples:
Notice how all the examples have at least two atoms in them? That’s what makes them a molecule. Now it’s time to look at compounds. Remember how compounds are molecules? Here is why. A compound is created when atoms of two different elements combine. You still have two atoms combining together, so it's definitely a molecule. But for it to be a compound, those elements must be different. For example:
Just in case the difference is still a little fuzzy, you can look at a few more examples of compounds.
Your head is swimming with atoms, compounds, and molecules. Keep everything straight with this simple breakdown of the difference between molecules and compounds.
Chemists like to throw around a lot of different terminology. Keeping it all straight can be hard. Since you have a clear understanding between molecule and compound, check out how they are different from an element and a mixture by reviewing all their definitions.
Chemistry is full of unique terminology, and now you know how they are different. You might have noticed chemistry terms build on one another. A structure with protons, electrons, and neutrons is an atom. Atoms with all the same protons are elements. Atoms that bond are molecules. And finally, different elements that bond are compounds. But without the atom, it would all tumble down. Now that you’ve explored the difference between molecule and compound, you can look at the difference between an atom and element. You might also find it interesting to explore the difference between an atom and a molecule.
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Which of the following statements best describes the difference between an element and a molecule?
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