Answer
(a) The atomic number denotes the number of protons in the atom's nucleus. In a neutral atom, the atomic number also denotes the number of electrons in that atom.
(b) The mass number is the number of protons and the number of neutrons within an atom's nucleus.
(c) The symbol for an element tells us what the element is; therefore, we also know the atomic number from the elemental symbol. If we know the atomic number of an atom of a given element, then we know the number of protons in that atom. In a neutral atom, the number of electrons is also given by the atomic number of that element.
Work Step by Step
(a) The atomic number denotes the number of protons in the atom's nucleus. In a neutral atom, the atomic number also denotes the number of electrons in that atom.
(b) The mass number is the number of protons and the number of neutrons within an atom's nucleus.
(c) The symbol for an element tells us what the element is; therefore, we also know the atomic number from the elemental symbol. If we know the atomic number of an atom of a given element, then we know the number of protons in that atom. In a neutral atom, the number of electrons is also given by the atomic number of that element.
