Simplicity vs. Complexity
The main difference between an element and a chemical compound is that an element is just one atom. The element is unable to be broken down further because it is already in its simplest form. There are 118 known elements, each with their own atomic number and weight. On the other hand, several elements can combine to form complex chemical compounds. For example, the elements sodium, carbon, oxygen and hydrogen form the complex compound of sodium percarbonate (also called sodium carbonate peroxyhydrate). Sodium percarbonate is actually the combination compound comprised of sodium carbonate (Na2CO3) and hydrogen peroxide (3H2O2).
Symbols and Formulas
Elements also differ from chemical compounds in that they are represented by their symbols. For example, the element oxygen is expressed by the letter "O", the element nitrogen is represented by "N" and potassium is represented by the letter "K." However, because chemical compounds are a mixture of two or more elements, a specific formula is used to represent all the chemical compounds in the formula. For example, the compound sodium chloride (also known as table salt) is represented by the formula NaCl. Uric acid is a more complex compound and its formula is C5H4N4O3.
Distinguishing Factor
Elements are recognized by their atomic number. For example, hydrogen has an atomic number of one, sodium has an atomic number of 11, aluminum has an atomic number of 13 and silver has an atomic number of 47. Compounds, on the other hand, are recognized by their chemical bonds. For example, table salt is formed by an ionic bond. An ionic bond is a bond that forms when one atom transfers one or more of its electrons to the other atom.
Ionic Bond Example
Sodium has one electron in its outer shell, while chlorine has seven electrons in its outer shell. So, the way it stands, neither element is quite stable. Sodium gives up its single outer electron to chlorine, thus making the element a positive ion. Chlorine gains the electron and therefore becomes a negative ion. The positive and negative charges are attracted to each other and held together by the electrostatic nature of the two elements. Once the bond forms, each element now has eight electrons in its outer shell, making both more stable.