An electron collides with a gold atom. Is it possible for two electrons to move away from the atom after the collision?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

If an electron collides with a gold atom, it is possible, though unlikely, for two electrons to move away from the atom after the collision. The gold atom would now be a cation, a positively charged ion with seventy-nine protons and seventy-eight electrons.

The experiment posited here is a variation...

See
This Answer Now

Start your 48-hour free trial to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Get 48 Hours Free Access

If an electron collides with a gold atom, it is possible, though unlikely, for two electrons to move away from the atom after the collision. The gold atom would now be a cation, a positively charged ion with seventy-nine protons and seventy-eight electrons.

The experiment posited here is a variation on ones conducted by Ernest Rutherford, Hans Geiger, and Ernest Marsden at the University of Manchester between 1908 and 1913. The physicists fired alpha particles, which are positively charged, at a thin sheet of gold foil. According to the standard model of atomic structure accepted at the time (the "plum-pudding model" proposed by Lord Kelvin and refined by Sir Joseph Thomson), all these particles should simply have passed straight through the atoms of the gold foil. Instead, a small proportion of them (about one in a thousand) were strongly deflected.

This result led Rutherford to conclude that electrons were not distributed throughout the atom like plums in a plum pudding, as Kelvin had thought. Instead, a cloud of them surrounds a tiny nucleus. Although the nucleus is tiny, it is still very much more massive than the electrons that surround it. Given that an electron is also very much smaller than an alpha particle, it is highly unlikely that, if it collided with a gold atom, it would hit one of the seventy-nine electrons. By far the most likely outcome is that it would pass straight through the atom with minimal deflection. Nonetheless, it is possible that it could hit another electron and move it out of the atom, ionizing the atom in the process.

Last Updated by eNotes Editorial on