Express the frequency in inverse seconds. n=4--> n=3. can you tell me what formulas to use, because i have like 6 more of these to do and i can't figure it out.

1.60×10¹⁴ s⁻¹

Explanation:

When an electron jumps from one energy level to a lower energy level some energy is released in the form of a photon.

The difference in energy between the two levels is the energy of the photon and that energy is related to the frequency of the photon by the Einstein - Planck equation:

E = hν

Where,

E = energy of the photon,h = 6.626×10⁻³⁴ J.s, Planck constant, andν = frequency of the photon.

So, to find the frequency you must first find the energy.

The transition energy can be calculated using the formula:

Eₙ = - E₀ ( 1/ n²)

Where E₀ = 13.6 eV ( 1 eV = 1.602×10⁻¹⁹ Joules) and n = 1,2,3,...

So, the transition energy between n = 4 and n = 3 will be:

ΔE = - E₀ [ 1/4² - 1/3²] = - 13.6 eV [1/16 - 1/9] = 0.6611. . .eVΔE = 1.602×10⁻¹⁹ Joules/eV  × 0.6611... eV = 1.0591 ×10⁻¹⁹ Joules

Now you can use the Einstein - Planck equation:

E = hνν = E / hν = 1.0591 ×10⁻¹⁹ J / 6.626×10⁻³⁴ J.s  = 1.60×10¹⁴ s⁻¹ (rounded to 3 significant figures).

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

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