Simulation · Chemistry · Class 11
Build a nuclide
From the lesson Atomic number, isotopes and isobars in Structure of Atom. Change the values and watch what happens.
Build a nuclideChemistry · Class 11
The idea behind it
NCERT §2.2.3; §2.2.4
- Atomic number Z = number of protons in the nucleus, which equals the number of electrons in a neutral atom (H: Z = 1; Na: Z = 11).
- Protons and neutrons together are nucleons; mass number A = protons + neutrons, so neutrons = A − Z whether the species is neutral or an ion.
- An atom is written with A as a left superscript and Z as a left subscript on the symbol, e.g. ⁸⁰₃₅Br has 35 protons, 35 electrons and 45 neutrons.
- For an ion, compare protons and electrons first: 16 protons, 16 neutrons and 18 electrons is ³²₁₆S²⁻, an anion carrying the two extra electrons as its charge.
- Isotopes have the same Z and different A, so they differ only in neutron count. Hydrogen: protium ¹H (99.985%), deuterium ²H or D (0.015%), and tritium ³H, found in trace amounts.
- Other isotopes: carbon with 6, 7 and 8 neutrons (¹²C, ¹³C, ¹⁴C) and chlorine with 18 and 20 neutrons (³⁵Cl, ³⁷Cl).
- Isobars have the same A and different Z, such as ¹⁴₆C and ¹⁴₇N.
- Chemical behaviour is set by the electrons, which the proton count fixes; neutrons hardly affect it, so isotopes of an element react alike.