A certain atom consists of 16 protons, 18 neutrons, and 16 electrons. What is its atomic number, mass number, and electron configuration?

Question

Peyton Adams · Accepted Answer

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, #Z#, tells you how many protons it has in its nucleus. Nothing more, nothing less. In your case, you are told that the atom contains #16# protons in its nucleus, which means that #Z# will be equal to #Z = 16# A quick look in the periodic table will reveal that you're dealing with an atom of sulfur, #"S"#. An atom's mass number, #A#, tells you how many protons and neutrons it contains in its nucleus. Since the number of protons is given by #Z#, you can say that #A = Z + "no. of neutrons"# In your case, the atom contains #18# neutrons in its nucleus. This means that #A# will be equal to #A = 16 + 18 = 34# Finally, focus on the atom's electron configuration, which you know that must account for a total of #16# electrons. #"S: " 1s^2 2s^2 2p^6 3s^2 3p^4# Its noble gas shorthand notation, which uses the electron configuration of neon, #"Ne"#, the noble gas that comes before sulfur in the periodic table, will look like this #"S: " ["Ne"] 3s^2 3p^4#

Natalie Anton · Answer

undefined The electron configuration is 1s2 2s2 2p6, 3s2 3p6, 4s2 3d10 4p6, and the atomic number is 16.