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Formula Sheet: Structure of Atom

This chapter introduces the structure of atoms, focusing on sub-atomic particles, atomic models, and quantum mechanics, which are fundamental to understanding chemistry.

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Structure of Atom – Formula & Equation Sheet

Essential formulas and equations from Chemistry Part - I, tailored for Class 11 in Chemistry.

This one-pager compiles key formulas and equations from the Structure of Atom chapter of Chemistry Part - I. Ideal for exam prep, quick reference, and solving time-bound numerical problems accurately.

Formula and Equation Sheet

Formula sheet

Key concepts & formulas

Essential formulas, key terms, and important concepts for quick reference and revision.

Formulas

1

E = hν

E is the energy (in joules) of a photon, h is Planck's constant (6.626 × 10⁻³⁴ J·s), and ν is the frequency (in Hz). This formula relates the energy of a photon to its frequency.

2

c = νλ

c is the speed of light (≈ 3 × 10⁸ m/s), ν is the frequency, and λ is the wavelength (in meters). This equation shows the relationship between the speed of light, its frequency, and wavelength.

3

ΔE = E_f - E_i

ΔE is the change in energy during a transition, E_f is the energy of the final state, and E_i is the energy of the initial state. It indicates the energy difference when an electron transitions between energy levels.

4

E_n = - (2.18 × 10⁻¹⁸ J/n²)

E_n is the energy of the nth orbit in hydrogen, where n is the principal quantum number. This formula quantifies the energy of an electron in a certain orbit.

5

r_n = n²a₀

r_n is the radius of the nth orbit, n is the principal quantum number, and a₀ is the Bohr radius (52.9 pm). This relation describes how the radius of orbits expands as n increases.

6

Z_eff = Z - S

Z_eff is the effective nuclear charge experienced by an electron, Z is the atomic number, and S is the shielding constant. This formula helps understand how inner electron shielding affects outer electron attraction.

7

λ = h/p

λ is the de Broglie wavelength, h is Planck's constant, and p is the momentum of the particle (mass × velocity). This equation shows the wave-like properties of matter.

8

E = mc²

E is energy, m is mass (in kg), and c is the speed of light (≈ 3 × 10⁸ m/s). This formula expresses the equivalence of mass and energy, foundational to modern physics.

9

Statistical distribution laws: (Number of orbitals in subshell) = 2l + 1

Where l is the azimuthal quantum number. This equation indicates how many orbitals exist within each subshell based on the shape defined by l.

10

n = 2, l = 0 (1s orbital)

An example of quantum numbers indicating the basic structure of atomic orbitals, where n is the principal quantum number and l is the azimuthal quantum number, defining the orbital shape.

Equations

1

ν_0 = W/h

ν_0 is the threshold frequency, W is the work function (energy needed to remove an electron), and h is Planck's constant. This equation defines the frequency required to emit electrons from a material.

2

K.E. = h(ν - ν_0)

K.E. is the kinetic energy of the emitted electron, and ν is the frequency of the incident light. This equation provides a link between incident light frequency and the energy of ejected electrons.

3

ΔE = hf

ΔE represents the energy difference between quantized states, h is Planck's constant, and f is the frequency of the emitted or absorbed radiation. This equation is crucial for understanding atomic transitions.

4

N = n²

N is the total number of orbitals in a principal energy level, representing the filled and unfilled states based on the principal quantum number n. This equation provides a systematic approach to electron configuration.

5

v = 3.29 × 10^15 (1/n^2)

This equation expresses the relationship of frequencies observed in the hydrogen spectrum transition from energy level n to ground state. It shows how spectral lines can be predicted.

6

E = - 2.18 × 10⁻¹⁸ Z²/n²

E is the energy of an electron in hydrogen-like atoms, Z is the atomic number, and n is the principal quantum number. This equation helps calculate the energy levels specific to different atomic species.

7

E = W + K.E.

E represents the total energy of a photon as it interacts with an electron, encompassing the work function (W) and the kinetic energy (K.E.) of the emitted electron after the reaction.

8

λ = h/mv

Where m is mass and v is velocity. This equation is also known as de Broglie equation, highlighting the wave-particle duality phenomenon, crucial for quantum mechanics understanding.

9

n = 1, l = 0 (1s), n = 2, l = 1 (2p)

These combinations of quantum numbers help define the electronic structure of atoms, reflecting the arrangement of electrons within orbitals.

10

Z = P + (-e)

Summarizes that for a neutral atom, the atomic number (Z) is equal to the number of protons (P) minus electrons (with a negative charge). This is a foundational concept for atomic structure.