A certain atom consists of 16 protons, 18 neutrons, and 16 electrons. What is its atomic number, mass number, and electron configuration?
Here's what I got.
So, you know that your atom contains
Right from the start, you know that you're indeed dealing with a neutral atom, since the number of protons it has in its nucleus is equal to the number of electrons it has surrounding its nucleus.
Now, an atom's atomic number,
In your case, you are told that the atom contains
#Z = 16#
A quick look in the periodic table will reveal that you're dealing with an atom of sulfur,
An atom's mass number,
#A = Z + "no. of neutrons"#
In your case, the atom contains
#A = 16 + 18 = 34#
Finally, focus on the atom's electron configuration, which you know that must account for a total of
#"S: " 1s^2 2s^2 2p^6 3s^2 3p^4#
#"S: " ["Ne"] 3s^2 3p^4#