For chlorine, identify the group number, give the number of electrons in each occupied shell, and write its valence-shell configuration.

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Welcome back everyone. We need to determine the group number of bromine provide the number of electrons each of its shells holds. And the electron configuration in its valence shell. So notice that on our attached periodic table we have roaming here in group seven a Notice that from Group three A. To Group ate A. We have our P blog Which represents one of our sub shells. Also take note that between group three B And Group two B. We have our D block Sub shell and then between group one a. And Group two A. We have our S block sub. Show next recall that our valence shell consists of our outermost electrons in the configuration of bromine in this case. And notice that on the periodic table in our textbooks when we look at roaming we see the number 35 above it And that tells us that its atomic number represented by the value Z is equal to 35. And so therefore because we have An atomic number of 35, we have 35 protons. And since we have neutral bromine, we also have 35 electrons. So now we need to think of each sorry, each sub shell for bro means electron configuration. And how many electrons are in each shell. Notice that for the beginning of its configuration we go through the one s to sub level. So we can note that down beginning with our shell which is the first energy level are sub shell which we stated is us and the number of electrons we set is one S two because recall that r s sub shell consists of one orbital which can hold a maximum of two electrons in which we represent our electrons with opposite spins. So an upward and downward arrow now moving forward. In our configuration to bromine, we get to the to S to sub level. So now our next shell is the second shell are sub shell is still the S sub shell. And moving forward. We also continue on and we get to R two P six sub shell. So we can include now Eskom api for the second show in the p sub shell. And recall that if R S sub shell can hold a maximum of two electrons are p sub shell. We should recall consists of three orbital's. So we have one orbital plus three more orbital's and our piece up shell holds a maximum of six electrons which we would fill up in this case since we need to keep moving forward until we hit remain. So we have 12345678 opposite lee spinned electrons filled in our four total orbital's. And this gives us a total of 2468 electrons. And so we can fill in that we have eight electrons were in our first orbital In the first shell we have two electrons now moving on to the next part of our configuration. We get to the three s two sub shell or shell. So the third energy level shell. And then our sub shell is the s sub shell comma notice that we keep going and we get to our three P six sub shell. So we still have our P sub shell included. We still have our S sub shell plus R three P sub shells. And then if we keep going in our configuration we would hit the four S two sub shell. But notice that we hit our D block before we get to bromine. And recall that our D block begins at the third energy level. And so technically we also can include for our third shell, the D block, recall that our D block has a maximum of five orbital's Which can hold 10 electrons maximum, so filling our electrons in with opposite spins in each orbital We would count a total of 18 electrons in our 3rd shell. And so after we go through three S 23 P 64 s 23 D 10, we finally hit our P block again where we see bro mean in period four group seven A and so we would count for 12345 units to hit the adam roaming, meaning that in our fourth shell we passed through our s block, we passed through our fourth level of R P block. And we have the s orbital plus our three p orbital's and the fourth energy level where we would fill in our s block completely. But in our P block because we only counted five units, we would fill in five electrons to get to remain so +1234. And actually let's fix this first orbital 1234 and then five can either be an upward or downward spin arrow, it's your preference. And so we would have a total of seven electrons. So so far we've confirmed our group number of bromine which is group seven a. We've confirmed the number of electrons in each of bro means shelves two electrons for the first shell, eight electrons for the second shell, 18 electrons for the third shell and seven electrons for the fourth shell. And now we just need the electron configuration of romaine and its valence shell. Since we do know that our outer valence shell is the fourth energy level, we can say that therefore our valence electron configuration is going to be four S two since we filled in two electrons there and then four P five. So this would be our last part of our final answer here, highlighted in yellow. And so our final answers all highlighted in yellow will correspond to choice A and the multiple choice as the correct answer. So I hope that this made sense. And let us know if you have any questions

For chlorine, identify the group number, give the number of electrons in each occupied shell, and write its valence-shell configuration.

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Key Concepts

Group Number

Electron Configuration

Valence Electrons