A sample of matter that contains atoms with the same number of protons is classified as what?

A sample of matter that contains atoms with the same number of protons is classified as an element because an element is defined as a pure substance made up of only one kind of atom, which all share the same atomic number. The atomic number signifies the number of protons in the nucleus of each atom, and this characteristic is what distinguishes one element from another in the periodic table.

For instance, all carbon atoms have six protons, which means that any sample of matter composed solely of carbon atoms is classified as the element carbon. In contrast, compounds consist of two or more different elements chemically bonded together, while mixtures are combinations of different substances that retain their individual properties. Isotopes refer to variations of a single element that have the same number of protons but different numbers of neutrons, which affects their mass but not their classification as an element.