posted by Danielle .
How many protons, neutrons, and electrons are in a flourin-19 atom?
The answer is 9 protons, 10 neutrons, and 9 electrons. How did they get this??
The atomic number for F is 9. Look at the periodic table and find F (in group VII or 17 depending upon the system being used). The atomic number is the number of protons. Since all elements are neutral that is ALSO the number of electrons. The number of neutrons is determined from
#protons + # neutons = mass number (19 in this case---that's what F-19 means)
When you know protons and mass number only one unknown is left for # neutrons.