Consider the following energy levels of a hypothetical atom: e4 −1.21 × 10−19 j e3 −5.71 × 10−19 j e2 −1.05 × 10−18 j e1 −1.55 × 10−18 j (a) what is the wavelength of the photon needed to excite an electron from e1 to e4? (b) what is the energy (in joules) a photon must have in order to excite an electron from e2 to e3? (c) when an electron drops from the e3 level to the e1 level, the atom is said to undergo emission. calculate the wavelength of the photon emitted in this process.

Explanation:

Energy levels of a hypothetical atom:

a) Wavelength of the photon needed to excite an electron from to .

Energy difference  between forth and first energy level =

139.2 nm is the wavelength of the photon needed to excite an electron from to .

b) Energy of a photon in order to excite an electron from to .

Energy difference between third and second energy level =

is the energy a photon to excite an electron from to .

c) Electron drops from the level to the level

Energy difference between third and first energy level =

202.3 nm is the wavelength of the photon of emitted.

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation:

a is the answer to this question

explanation: