Structure of Atom

Chemistry · Class 11

Simulation · Chemistry · Class 11

Build a nuclide

"Build a nuclide" is a free, interactive Class 11 Chemistry simulation for NEET and JEE, built on the NCERT section "Atomic number, isotopes and isobars" in Structure of Atom. Add or remove protons, neutrons and electrons; the nuclide symbol with A, Z and charge updates, and isotopes/isobars of the current nuclide are highlighted. NEET has asked about this idea 2 times in 10 years of papers. JEE Main asked 46 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Atomic number, isotopes and isobars in Structure of Atom. Change the values and watch what happens.

Build a nuclideChemistry · Class 11

What it shows

NCERT §2.2.3; §2.2.4

Add or remove protons, neutrons and electrons; the nuclide symbol with A, Z and charge updates, and isotopes/isobars of the current nuclide are highlighted.

Controls

3 to try

  • Sliderprotons 1–20
  • Sliderneutrons 0–24
  • Sliderelectrons 0–22

Try this

Build ³²₁₆S²⁻ (16 p, 16 n, 18 e); then change one particle count to make an isobar of it.

Common mistake

Neutrons = A − electrons for an ion (it is always A − Z).

In NEET

10 years of papers

Asked 2 times in 10 years of NEET.

See the past questions: Quantum Numbers, Structure of Atom (chapter)

In JEE Main

42 shifts analysed

46 questions from Structure of Atom across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

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.

Questions

5 answers

What does the "Build a nuclide" simulation show?
Add or remove protons, neutrons and electrons; the nuclide symbol with A, Z and charge updates, and isotopes/isobars of the current nuclide are highlighted.
What mistake does the "Build a nuclide" simulation fix?
A common mistake it clears up: neutrons = A − electrons for an ion (it is always A − Z).
Has NEET asked about this idea?
Yes. NEET has asked about this idea 2 times in 10 years of papers.
Does JEE Main ask questions from Structure of Atom?
Yes. JEE Main asked 46 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Atomic number, isotopes and isobars" in Structure of Atom (Class 11 Chemistry).

Embed this simulation

Free, with a link back

Teaching this idea? Put the simulation on your own page or LMS with this code.