Final answer:
The atomic number (Z) is defined by the number of protons in an atom's nucleus and determines the identity of an element. Each element has a unique atomic number corresponding to the number of protons, which also equals the number of electrons in a neutral atom. This number is essential for distinguishing one element from another and is used in organizing the periodic table.
Step-by-step explanation:
One important thing to remember about protons and atomic number is that the number of protons in the nucleus of an atom is its atomic number (Z). This atomic number is crucial because it uniquely identifies each element. All atoms of a specific element share the same number of protons, making each element distinct.
For example, any atom containing six protons is identified as the element carbon, which means it has an atomic number of 6. Additionally, the atomic number also tells us the number of electrons in a neutrally charged atom since a neutral atom has an equal number of protons and electrons.
When referring to the periodic table, elements are arranged in order of increasing atomic number. Hydrogen, for instance, is at the top left of the table and has an atomic number of 1, meaning each hydrogen atom has one proton (and one electron when neutral). The atomic number is also relevant when determining the number of neutrons in an atom by subtracting the atomic number from the mass number of the atom (A - Z = number of neutrons).