Atomic Number
* Definition: The atomic number represents the number of protons in an atom's nucleus.
* Key Points:
* Unique identifier: Every element has a unique atomic number. It defines the element.
* Location on the periodic table: Elements are arranged on the periodic table by increasing atomic number.
* Neutral atoms: The number of protons is equal to the number of electrons in a neutral atom.
Atomic Mass
* Definition: The atomic mass is the average mass of an atom of an element, taking into account the different isotopes of that element.
* Key Points:
* Weighted average: It's not the mass of a single atom, but an average based on the abundance of each isotope.
* Units: Measured in atomic mass units (amu).
* Isotopes: Isotopes are atoms of the same element with the same number of protons but a different number of neutrons, resulting in different atomic masses.
In Summary
* Atomic number (Z): Defines the element, based on the number of protons.
* Atomic mass (A): Represents the average mass of an atom of that element, taking into account all its isotopes.
Example
Let's take carbon (C):
* Atomic Number (Z): 6 (meaning it has 6 protons)
* Atomic Mass (A): Approximately 12.011 amu (due to the presence of isotopes like carbon-12 and carbon-14)
Remember: While the atomic number is a whole number, the atomic mass is usually a decimal because it's a weighted average of the isotopes.
