Question

use your observations to explain how each type of partic contributes to identify of the element the net charge and mass number

Answer 1

Short answer:
- Protons (p+) determine the element (atomic number Z) and, together with electrons, determine net charge.
- Neutrons (n0) add mass and produce isotopes (mass number A = Z + N).
- Electrons (e–) set the net charge (relative to protons) but contribute almost no mass.

Details and quick rules
- Particle properties:
- Proton: charge +1 (in units of e), mass ≈ 1 atomic mass unit (u). Number = Z (atomic number) → identifies the element.
- Neutron: charge 0, mass ≈ 1 u. Number = N. Neutrons change mass and nuclear stability but not chemical identity.
- Electron: charge −1, mass ≈ 1/1836 u (negligible for mass number). Number = E.

- Mass number (A): A = Z + N = number of protons + number of neutrons. A is the integer shown in isotope notation (for example, 14C has A = 14).
- Net charge (in units of e): Q = (+1)·Z + (0)·N + (−1)·E = Z − E. Often written as a charge on the ion (e.g., Na+, Ca2−).
- Neutral atom: E = Z so Q = 0.
- Cation: E < Z, Q positive (e.g., Na+ has Z = 11, E = 10 → Q = +1).
- Anion: E > Z, Q negative (e.g., Cl− has Z = 17, E = 18 → Q = −1).

- Writing isotopes/ions: A
Z X^charge
Example shorthand: 14
6 C (or C-14) means Z = 6, A = 14 → N = A − Z = 8 neutrons.

Examples
- Carbon-12 vs Carbon-14: both Z = 6 (same element). C-12 has N = 6 (A = 12), C-14 has N = 8 (A = 14). Different masses and radioactive behavior, same chemistry.
- Sodium: neutral Na atom Z = 11, E = 11 → Q = 0, A typically 23 (so N = 12). Na+ ion: E = 10 → Q = +1.
- Chloride: Cl neutral Z = 17, typical A = 35 (N = 18). Cl− has E = 18 → Q = −1.

Note: “Atomic mass” listed on the periodic table is a weighted average of isotopic masses; it is not the same as the integer mass number A except in simple cases.