Carbon atoms with the same number of neutrons are called isotopes of carbon. Carbon-12 (⁶C¹²) and Carbon-13 (⁶C¹³) are two isotopes of carbon. They both have six protons and six electrons but differ in the number of neutrons. ⁶C¹² has six neutrons, while ⁶C¹³ has seven neutrons.

Isotopes of an element have the same atomic number but different mass numbers. The atomic number of an element is the number of protons in the nucleus of an atom, while the mass number is the sum of the number of protons and neutrons in the nucleus of an atom.

Isotopes of an element have different physical properties, such as density and melting point. However, they have the same chemical properties, such as reactivity. This means they react with other elements in the same way.

Isotopes of an element can be used to study different phenomena, such as radioactive decay and nuclear reactions. They can also be used to produce different materials with different properties. For example, ⁶C¹³ is used in nuclear reactors to produce heat and power.