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Atomic electron transitions can be caused by absorbing a photon with a certain wavelength. An electron jumps to an higher energy level, then it falls back and a photon is emitted. The perceived color of the photon depends on the energy absorbed by the electron.

Could we say that electrons in the atoms of different objects are excited when white light hits them, and they release photons which in turn causes the object have a color?

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  • $\begingroup$ Unlikely, consider copper vs copper powder $\endgroup$ May 3, 2020 at 15:53

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Could we say that electrons in the atoms of different objects are excited when white light hits them, and they release photons which in turn causes the object have a color?

What you describe there is known as fluorescence but that's not what happens when white light hits a coloured object, at least not in most cases.

Most objects are made up of molecules. These molecules are in turn made up of atoms, bound together by so-called molecular orbitals (MO, aka bonds).

When a photon of the right wavelength (and thus right energy) hits an electron in an MO the photon is absorbed and the electron is moved to a state of higher energy.

The white light, minus some of the absorbed photons, causes the reflected (or transmitted, in the case of transparent objects) light now to appear coloured.

So the phenomenon is caused by VIS photon absorption, not fluorescence.

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  • $\begingroup$ In case of a metal, a molecular orbital can be very large (much larger than a molecule in the usual sense) and the term band is very common for this situation. Also, I'd say just "absorption", not "VIS photon absorption" (in contrast to "fluorescence"). $\endgroup$
    – zonksoft
    May 9, 2020 at 15:27
  • $\begingroup$ In fluorescence, the photons goes from S0 to S1, has non radiative transition at S1 and then goes down by emitting a photon of longer wavelength. But in colors of ordinary objects, is it not the photons also got excited from S0 to S1 and got back to S0 and emitting the same photons producing colors? I have been thinking of these for days so pls clarify, thanks. $\endgroup$
    – Jtl
    Aug 27, 2022 at 20:05
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    $\begingroup$ @Jtl. No, mostly the colour of objects are caused by absorption. The remaining, not absorbed wavelengths then cause colour. See also anna v.'s answer. $\endgroup$
    – Gert
    Aug 27, 2022 at 20:29
  • $\begingroup$ Yes, rest of colors are absorbed. but is it not the photons that get reflected need to firat climb up from S0 to S1 and then emit the same photons when they got back to ground state? $\endgroup$
    – Jtl
    Aug 27, 2022 at 22:06
  • $\begingroup$ @Jtl I'm sorry but I really don't get your question? Perhaps see 'elastic scattering'? $\endgroup$
    – Gert
    Aug 28, 2022 at 11:23
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In addition to the other answers one should add color perception. White light contains all frequencies, if some are absorbed the scattered back light will have a different spectrum perceived differently by the receptors in our eyes.

colperc

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No, actually what you are talking about is the atomic spectrum of an atom or a system. The colour of a object depends on the crystal structure of the object. As @user12986714 gave the example, copper has crystalline structure which cause the constructive interference of light wave of particular frequency between two crystal layers,. While copper powder is almost amorphous and there is no interference of light wave so it is white in colour.

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