The atomic number of an element is determined by the number of protons in the nucleus of an atom. This number is unique for each element and is the basis for organizing the periodic table.
The atomic number also tells us the number of electrons in a neutral atom. This is because atoms are electrically neutral, meaning they have an equal number of positively charged protons and negatively charged electrons.
The atomic number of an element cannot change, as it is a fundamental property of an element. However, the number of neutrons in an atom can vary, resulting in different isotopes of the same element with the same atomic number.
New elements are typically discovered through experiments and observations using advanced technology. Scientists can determine the atomic number of a new element by studying its chemical and physical properties, as well as analyzing the behavior of its atoms.
The atomic number is significant because it provides a unique identifier for each element and determines its placement in the periodic table. It also helps to predict an element's chemical and physical properties, as well as its reactivity with other elements.