Question Video: Reading Number of Electrons, Protons, and Neutrons from Atomic Number and Mass Number Chemistry

A carbon atom has an atomic number of 6 and a mass number of 12. a) How many protons are there in an atom of carbon? b) How many neutrons are there in an atom of carbon? c) How many electrons are there in an atom of carbon?

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Video Transcript

A carbon atom has an atomic number of six and a mass number of 12. How many protons are there in an atom of carbon?

The atomic number of an atom represents the number of protons in the nucleus. All atoms, isotopes, and ions of an element will have the same atomic number. When looking at a cell on the periodic table, the atomic number will frequently be written above the element symbol. If the carbon atom has an atomic number of six, then there must be six protons in an atom of carbon.

How many neutrons are there in an atom of carbon?

Protons and neutrons are collectively found in the nucleus of the atom. The total number of protons and neutrons in the nucleus is the mass number. This carbon atom has a mass number of 12. And we established in part (a) that the carbon atom has six protons. We can substitute the mass number and number of protons into the equation and solve for the number of neutrons. The number of neutrons in an atom of carbon that has a mass number of 12 is six.

How many electrons are there in an atom of carbon?

Atoms consist of positively charged protons, neutral neutrons, and negatively charged electrons. Despite containing positively charged protons and negatively charged electrons, the atom as a whole will have a net neutral charge. This is because the number of positively charged protons is equal to the number of negatively charged electrons. Therefore, if a carbon atom contains six protons, the atom must also contain six electrons in order to have a net neutral charge.

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