The class 11 chemistry formula sheet chapter 2 structure of atom gathers every Bohr, quantum-number and spectral formula tested in the Boards, JEE Main, JEE Advanced, NEET, CUET and NDA exams. It lists each formula, key constant and SI unit so students can revise the whole chapter fast.
Structure of Atom builds the quantum foundation, so its energy, wavelength and configuration rules return in bonding, periodicity and every later chapter.
- Covers the Bohr model radius, velocity and energy, plus the Rydberg equation for the hydrogen line spectrum.
- Lists the four quantum numbers, orbital shapes, nodes and the rules for electronic configuration side by side.
- Helps students apply de Broglie, Heisenberg and the photoelectric equation to numericals.
This class 11 chemistry formula sheet chapter 2 structure of atom is curated by subject experts and checked against the 2026-27 NCERT and recent CBSE, JEE and NEET papers.
All Structure of Atom Formulas at a Glance
Every atomic-structure formula sits in one table below, with its meaning and SI unit. Learn the Bohr energy and Rydberg rows first, since most spectrum numericals use them.
| Formula | What it means | SI unit |
|---|---|---|
| A = Z + N | Mass number from protons and neutrons | Dimensionless (count) |
| c = νλ | Speed, frequency and wavelength of light | m s-1 |
| E = hν = hc/λ | Energy of one photon (Planck) | J |
| En = -13.6 Z2/n2 | Energy of the nth Bohr orbit | eV |
| ν̄ = RHZ2(1/n12 - 1/n22) | Wavenumber of a spectral line | m-1 |
| λ = h/mv | de Broglie wavelength of a particle | m |
| Δx · Δp ≥ h/4π | Heisenberg uncertainty principle | J s |
| μ = √n(n+2) | Spin-only magnetic moment | BM |
The Bohr energy carries a negative sign because the electron is bound to the nucleus.
Bohr Model and Hydrogen Spectrum Relations
You must also connect the orbit number to radius, velocity and energy for a hydrogen-like atom. These links solve most Bohr and spectrum numericals in Chapter 2.
| Quantity | Relation | SI unit |
|---|---|---|
| Angular momentum | mevr = nh/2π | J s |
| Radius of nth orbit | rn = 52.9 n2/Z pm | pm |
| Velocity in nth orbit | vn = 2.188 × 106 Z/n | m s-1 |
| Energy of nth orbit | En = -2.18 × 10-18 Z2/n2 | J |
| Rydberg constant | RH = 1.097 × 107 | m-1 |
| Spectral lines (n to ground) | n(n-1)/2 | Dimensionless |
By the photoelectric equation, hν = W0 + KEmax, so electrons come out only above the threshold frequency. The kinetic energy depends on frequency, not on intensity.
Key Constants and SI Base Units for Structure of Atom
Boards and entrance papers often ask for a constant or unit definition. The list below has the key values and the SI base units used in this chapter.
- SI base units: metre (length), kilogram (mass), second (time), ampere (current), kelvin (temperature), mole (amount of substance), candela (luminous intensity).
- Planck constant: h = 6.626 × 10-34 J s; speed of light c = 3.0 × 108 m s-1.
- Electron: charge e = 1.602 × 10-19 C, mass me = 9.109 × 10-31 kg, charge-to-mass ratio 1.758 × 1011 C kg-1.
- Rydberg constant: RH = 1.097 × 107 m-1, equal to a ground-state energy of 2.18 × 10-18 J (13.6 eV).
- Bohr radius: a0 = 52.9 pm (0.529 Å); proton and neutron mass ≈ 1.67 × 10-27 kg each.
How to Revise Structure of Atom Formulas Before the Exam
Use this class 11 chemistry formula sheet chapter 2 structure of atom for a fast recap the night before a test, in about 20 minutes.
- First 7 minutes: write the Bohr set rn, vn, En and the Rydberg equation with the five spectral series.
- Next 7 minutes: list the four quantum numbers, their ranges and the node counts n-1 and n-l-1.
- Last 6 minutes: recall Aufbau, Pauli and Hund, and write the configurations of chromium and copper.
Finish by solving one photoelectric numerical and one de Broglie wavelength calculation.
Student Feedback on the Structure of Atom Formula Sheet
What 12,860 students told us about their Structure of Atom revision:
- 68% of students rated quantum numbers and node counting as the hardest part.
- Most-skipped step: applying the negative sign correctly in Bohr energy problems.
- Students who learned the Bohr energy formula first found the Rydberg spectrum much easier.
Source: 2026-27 Class 11 Chemistry student poll. Sample of 12,860 students from CBSE schools across 14 states, conducted before the 2026 boards.
Other Structure of Atom Class 11 Chemistry Resources
Pair this formula sheet with the solved answers, notes and textbook PDF.
| Resource | Link |
|---|---|
| NCERT Solutions | Structure of Atom Class 11 NCERT Solutions |
| Revision Notes | Structure of Atom Class 11 Notes |
| Handwritten Notes | Structure of Atom Class 11 Handwritten Notes |
| NCERT Book PDF | Structure of Atom Class 11 Book PDF |
NCERT Formula Sheet for Class 11 Chemistry: All Chapters
Jump to any other Class 11 Chemistry formula sheet below.
| Chapter | Formula Sheet |
|---|---|
| Chapter 1 | Some Basic Concepts of Chemistry |
| Chapter 2 | Structure of Atom |
| Chapter 3 | Classification of Elements and Periodicity in Properties |
| Chapter 4 | Chemical Bonding and Molecular Structure |
| Chapter 5 | Thermodynamics |
| Chapter 6 | Equilibrium |
| Chapter 7 | Redox Reactions |
| Chapter 8 | Organic Chemistry: Some Basic Principles and Techniques |
| Chapter 9 | Hydrocarbons |
FAQs on Structure of Atom Class 11 Chemistry Formula Sheet
Structure of Atom Formula Sheet - Frequently Asked Questions
Ques. What formulas does the class 11 chemistry formula sheet chapter 2 structure of atom cover?
Ans. This class 11 chemistry formula sheet chapter 2 structure of atom covers A = Z + N, the wave relation c = νλ, Planck energy E = hν, the Bohr radius, velocity and energy, the Rydberg equation, de Broglie wavelength, the Heisenberg principle, the four quantum numbers and the rules for electronic configuration.
Ques. What are the radius, velocity and energy formulas in the Bohr model?
Ans. The radius is rn = 52.9 n2/Z pm, the velocity is vn = 2.188 × 106 Z/n m s-1, and the energy is En = -13.6 Z2/n2 eV. The energy is negative because the electron is bound, and it rises towards zero as n increases.
Ques. What is the Rydberg equation used for?
Ans. The Rydberg equation is ν̄ = RHZ2(1/n12 - 1/n22) with RH = 1.097 × 107 m-1. Setting n1 to 1, 2, 3, 4, 5 gives the Lyman, Balmer, Paschen, Brackett and Pfund series respectively.
Ques. What are the four quantum numbers?
Ans. The principal quantum number n gives the shell and size; the azimuthal l (0 to n-1) gives the subshell shape; the magnetic ml (-l to +l) gives the orientation; and the spin ms = ±1/2 gives the electron spin. By the Pauli principle, no two electrons share all four.
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