The atomic number on the periodic table represents the number of protons in the nucleus of an atom of an element. It is denoted by the symbol "Z" and is a unique identifier for each element. The periodic table arranges elements in order of increasing atomic number.
The atomic number serves as a fundamental characteristic of an element because it determines its chemical properties. Elements with the same atomic number have similar chemical behavior, while elements with different atomic numbers have distinct properties.
To determine what elements make up a substance, you can analyze its composition using techniques like spectroscopy or elemental analysis. These methods involve identifying the types and quantities of atoms present in a sample.
For example, if you want to determine the elements in a sample of oxygen gas (O₂), you know that oxygen has an atomic number of 8. This means each oxygen atom has 8 protons. By analyzing the sample using spectroscopy or other analytical techniques, you can detect the presence of oxygen by identifying the characteristic spectra or elemental composition associated with atomic number 8.
By comparing the atomic number of an element to the periodic table, you can identify the specific element or elements present in a substance based on their atomic numbers and known properties.