Atoms are tiny particles that make up the universe, while molecules are made from atoms (even a single atom). However, both constitute small, identifiable units.Know More
Atoms are what make up everything from pencils to humans to the ocean. At one time, scientists thought they were the smallest possible particle and that they were indivisible; however, they can be divided. Each atom has a nucleus made of protons and neutrons surrounded by orbiting electrons. Protons are positively charged, and electrons are negatively charged. Neutrons are neutral. All three of these particles can be divided up into smaller particles called quarks. The number of protons, neutrons and electrons an atom has determines what element it is. For instance, sodium has 11 protons, 11 electrons, and 12 neutrons.
A molecule, on the other hand, is indivisible in its own way: by definition, it is the smallest particle of a substance that still retains the properties of that substance. Therefore, although it can be divided into smaller parts (atoms and so on), it does make a unit. Single atoms can make up a molecule, such as the noble gases.
Most molecules are formed when atoms bond in a particular way. For instance, the chemical formula for water is H20, meaning that two hydrogen atoms bond with one oxygen atom. One set of this compound, exactly two hydrogen atoms and one oxygen atom, makes a molecule. If it were divided again, it would be hydrogen and oxygen atoms, not water.Learn more about Atoms & Molecules
The difference between an atom and a molecule is that molecules are composed of two or more atoms. Atoms are the smallest units of matter and, when they join chemically, they form a molecule.Full Answer >
The atomic number of an atom is the number of protons that resides in the nucleus, while the mass number is the number of protons and neutrons combined. The atomic number determines the type of element an atom, while the number of neutrons determines the isotope of the element. Many elements naturally occur in the form of several different isotopes.Full Answer >
A sample of a given element can consist of a single atom of that element, and so there is no fixed quantity of molecules required to make up an element. In the universe at large, however, hydrogen is by far the most abundant element.Full Answer >
A monoatomic ion is one that forms from a single atom. Ions with a positive charge, such as sodium (Na+) are cations. Those with a negative charge, such as chlorine (Cl-) are anions. Monoatomic ions are also known as simple ions.Full Answer >