An atom contains six electrons. How many protons does the nucleus
of the atom have?
The question tells us that an atom
contains six electrons. Electrons are negatively
charged. To balance out this negative
charge, atoms have positively charged protons in the nucleus. But the question is “how many?”
Electrons and protons have relative
charges of minus one and plus one, respectively. The six electrons, therefore,
contribute a charge of minus six. But the question tells us that the
species is an atom, not an ion. Thus, it will not have an overall
charge. This means the protons must
contribute a charge of positive six. As each proton has a relative
charge of plus one, the nucleus will contain six protons. It will also contain neutrons, but
neutrons won’t be discussed in this video.
We can therefore see that for a
neutral atom the number of protons is equivalent to the number of electrons. So, a neutral atom with six
electrons will contain six protons in its nucleus.