Elements are more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e., the number of protons in the nuclei of its atom, also known as the basic unit of a chemical element. Protons are subatomic particles, which are particles smaller than an atom. Electrons, and neutrons are also examples of subatomic particles but they all have different charges. A proton has a positive charge, an electron has a negative charge, and a neutron has no charge. Molecules, also known as groups of atoms bonded together, form chemical compounds that take part in a chemical reaction. Molecules use bonds to form into compounds. An ionic bond is a chemical bond in which the atom transfers electrons while a covalent bond is a chemical bond in which the atoms share electrons. A chemical formula is a way of expressing the information about what makes up the compound. Two examples of compounds are organic compounds, and inorganic compounds. Organic compounds are made up of the elements carbon and hydrogen, while inorganic compounds have either of the elements, hydrogen and carbon. Macromolecules also known as “big molecules,” are made from thousands or even hundreds of thousands of even smaller molecules. Four examples of macromolecules are proteins, carbohydrates, lipids, and nucleic acids. Carbohydrates are made up of monosaccharides, simple sugar molecules that