The atomic number of carbon-13 is thirteen. The atomic mass of carbon-13 is thirteen. If different atoms have the same number of protons but different numbers of neutrons they are called . Substances composed of atoms that all have the same number of protons are called . Atoms that have gained or lost electrons and are no longer electrically neutral are called . The nucleus of an atom always contains one or more . The orbitals of an atom contain negatively charged particles called .

Explanation:

If different atoms have the same number of protons but different numbers of neutrons they are called _ISOTOPES . Substances composed of atoms that all have the same number of protons are called ___ISOTOPES . Atoms that have gained or lost electrons and are no longer electrically neutral are called IONS . The nucleus of an atom always contains one or more _NUCLEONS . The orbitals of an atom contain negatively charged particles called __ELECTRONS

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.