Symbols \(_{79}^{35}\textrm{Br}\) and \(_{79}^{}\textrm{Br}\) can be written, whereas symbols \(_{35}^{79}\textrm{Br}\) and \(_{35}^{}\textrm{Br}\) are not acceptable. Answer briefly.

Question

The energy of the nth orbit of the hydrogen atom is given by: \[ E_n = - \frac{13.6}{n^2} \, \text{eV} \] What is the energy of the second orbit (n = 2) of the hydrogen atom?

Answer 1

Concept Used:

In atomic notation:

^A_ZX

where,
A = mass number (protons + neutrons)
Z = atomic number (number of protons)
X = symbol of the element

Explanation:

For bromine (Br), the atomic number is fixed as 35.

Hence, symbols such as:

⁷⁹₃₅Br and ⁷⁹Br

are acceptable because they correctly represent bromine with atomic number 35 and mass number 79.

However, symbols like:

³⁵₇₉Br and ₃₅Br

are not acceptable because they imply that bromine has an atomic number of 79, which is incorrect. Atomic number uniquely identifies an element and cannot be changed.

Final Answer:

Only those symbols in which the atomic number of bromine is correctly written as 35 are acceptable.

Symbols \(_{79}^{35}\textrm{Br}\) and \(_{79}^{}\textrm{Br}\) can be written, whereas symbols \(_{35}^{79}\textrm{Br}\) and \(_{35}^{}\textrm{Br}\) are not acceptable. Answer briefly.

Solution and Explanation

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