Helium (He)

Practice

Practice helium

Questions from the course about helium. If you’re signed in, your answers count toward your progress.

1. Question 1Energy levels of hydrogen-like ionsExam level

   What is the energy of the electron in the $n = 2$ level of a $\ce{He+}$ ion, in J? Include the sign. ($R_H = 2.179 \times 10^{-18}\ \mathrm{J}$)

   Your answer (in the unit shown)

   $\mathrm{J}$

   Scientific notation: type 4.86e-7 or 4.86 x 10^-7.

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2. Question 2Wavelength of a hydrogen-like transitionChallenging

   What is the wavelength, in nm, of the light emitted when the electron in a $\ce{He+}$ ion falls from $n = 4$ to $n = 3$? ($R_H = 2.179 \times 10^{-18}\ \mathrm{J}$)

   Your answer (in the unit shown)

   $\mathrm{nm}$

   Scientific notation: type 4.86e-7 or 4.86 x 10^-7.

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3. Question 3MO bond orderExam level

   Use molecular-orbital theory to find the bond order of $\ce{He2+}$. Give a decimal if needed (e.g. 1.5).

   Your answer

   Scientific notation: type 4.86e-7 or 4.86 x 10^-7.

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