You are watching: Which element has 3 valence electrons
The prize is Cl.
Group/family 18, the Nobel Gases, have full octets that 8 valence electrons. Each time you relocate to the LEFT one time within the nonmetals on the regular Table, an electron is lost. So, any type of element in group/family 17 would have 7 valence electron (you have the right to check...
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The prize is Cl.
Group/family 18, the Nobel Gases, have complete octets of 8 valence electrons. Every time you relocate to the LEFT one time within the nonmetals ~ above the routine Table, one electron is lost. So, any kind of element in group/family 17 would have 7 valence electrons (you can inspect this by drawing Bohr diagrams because that each facet within group/family 17).
So, us now understand that the element is a nonmetal uncovered in group/family 17. Therefore, that is found in the "p" block. For elements found in the "p" block, durations represent power levels.
Thus, if I match the third duration with group/family 17, ns have uncovered my answer- Chlorine!
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use the routine Table to answer such questions. The valence electrons space those in the outermost power level and are regularly used in bonding. Each household (or group or column) top top the PT have actually a specific number of valence electrons. For instance Group 1, the alkali metals, (Li, Na, K, etc.) have actually 1 valence electron. Team 2, the alkaline earth metals, (Be, Mg, Ca, etc.) have 2 valence electrons. Groups 3-12, the change metals, have actually 2 valence electrons (most that them) yet some have d electrons that might be involved in bonding too. Team 13 facets have 3 valence electrons. Team 14 facets have 4 valence electrons. Group 15 elements have 5 valence electrons. Team 16 facets have 6 valence electrons. Group 17 aspects have 7 valence electrons. Team 18 elements have 8 valence electrons.
So from the description, you deserve to conclude that the facet described, with 7 valence electrons, should be in team 17.
Next you need to decipher what the three energy levels indicates. The electrons fill up the power levels in the electron cloud indigenous the lowest level first. As soon as that power level is filled, the electrons begin to fill the next highest power level. Interestingly, the periodic table is collection up such that aspects in the an initial row (Period 1) have their valence electrons in the an initial energy level. Duration 2 aspects have your valence electron in the second energy level, etc.
So indigenous the description, the facet has three energy levels. It"s valence electrons need to be in the 3rd energy level, and therefore the aspect must be in duration 3 on the regular Table.
Thus the element described need to be in period 3, team 17, i m sorry is Chlorine, prize Cl.
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This is a very broad scientific research question regarding elements. Based upon the info that was listed one deserve to narrow under the pool of elements to a particular family or group of elements.
The three orbitals is essential information but it is general due to the fact that most aspects that have actually over 11 electron will have a 3rd orbital. The far-reaching bit of information detailed was the valence electrons. Valence electron tells us that it has actually seven electron in its outermost orbital. Through that in mind, we deserve to narrow the facet down come the Halogens or team 17.
In regards to which certain element, the clue that the valence electrons space in the 3rd orbital narrows it to Chlorine. The remaining elements would not have actually seven valence electron in the 3rd orbital.
What is the the prize of the element that has three power levels and seven valence electrons?
This can be quickly done using your routine table. The rows the a routine table indicate the number of energy level an aspect has. So to discover an facet with three power levels you desire to walk to the 3rd row down. Now to find the element with 7 valence electron you can use the columns (aka groups) an aspect is in. The very first column means those elements have 1 valence electron, the second column means those elements have 2 valence electrons, and also so on. The just tricky part is you have to skip the change metals (the middle group). The trend picks increase again on obelisk 13, those aspects have 3 valence electrons, group 14 has actually 4 valence electrons, team 15 has actually 5 valence electrons, team 16 has 6 valence electrons, and group 17 has 7 valence electrons. So we are in search of the aspect in the third row and also 17th group or column and also there we will find Chlorine, symbol Cl.
your question requires electron configurations, valence electrons, and also the routine table, every in one. There are multiple means to resolve this question, all arriving at the same answer. I"m not certain which makes the most sense come you, yet here that goes:
1. The Aufbau principle (long way)
For this question, friend no doubt have currently referenced and learned the Aufbau principle because that electrons, the order in ~ which electrons fill the various power levels and sublevels around a nucleus. While known the bespeak is best, don"t be afraid to look it increase in her textbook. You"ll uncover a selection of ways describing it, yet you have to see the diagonal dominion attached come this answer which travel guide you v them. You have to know around the different sublevels (s,p,d, and also f) and the number of electrons each have the right to hold (2, 6, 10, and 14). As soon as looking in ~ the coefficients of each letter, you"re in reality seeing the various energy levels that the sublevels belonging to. For her question, you desire the aspect that has three power levels and also 7 valence electrons, or 7 electron on the third energy level. If girlfriend trace with the image, the an initial sublevel you hit on the third energy level is the 3s, which can only hold 2 electrons. Because you want 7 valence electrons, you need to account because that the various other 5. If you keep tracing the image, you then involved the 3p sublevel, which deserve to hold 6, yet you only have 5 left. This way that the last component of your configuration need to be 3p^5. According to the Aufbau principle, each power level (and sublevel) have to be filled prior to you fill the next. In other words, everything prior to 3p should be full. Map along the diagonal rule and also you arrive at:
1s^2 2s^2 2p^6 3s^2 3p^5
Each superscript (exponent) tells you how many electrons space in every sublevel. If you add them all up, you have actually 17. Thus, this aspect that has three power levels and 7 valence electrons must have actually 17 electron total. When you look at the periodic table, chlorine, Cl, is atomic number 17.
2. The Aufbau Principle and the routine Table (the simpler way)
The much more electron configuration you job-related out and study, the an ext comfortable girlfriend will come to be with them. The odd form of the regular table stems from the arrangement of all the electrons approximately a nucleus for each element. Attached, you"ll find another image because that the Aufbau principle, except it overlaps the routine table. To make feeling of it, begin in the top left in ~ hydrogen, and then trace your finger come the best (helium). Then go to heat two, starting at whereby lithium is found and also again trace appropriate until you find neon. If you proceed in this pattern, girlfriend are adhering to the bespeak of the sublevels. Your question asks because that an element with three energy levels and also 7 valence electrons. If you map the regular table, the very first time you find something top top the third energy level is 3s (the third row). If you map that row, you"ll relocate one clues over and fill the 3s sublevel. Friend would have covered 2 aspects for the 2 electron an s deserve to hold. 5 much more valence electrons need to be accounting for. If you proceed tracing that row, counting follow me the way, you"ll discover yourself in the p-block. If you count to 5 in the p-block, you"ll prevent in the place that chlorine can be found on a standard regular table. That is the 7th aspect on row three of the periodic table, 5th element in p-block on heat three. Her answer is again chlorine, Cl.
3. The periodic table and also groups (easiest way)
The team numbers on the routine table reference electron configurations. Elements in team 17 or group VIIA (same group), lock will have 7 valence electrons. The row or duration an facet is found on referrals the highest occupied energy level for the element. Because that an facet to have actually three occupied energy levels and also 7 valence electrons, it should be on heat three and also in team 17 or group VIIA. Again, you discover chlorine, Cl.
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They each arrive in ~ the same answer. The only difference is which means your brain likes to see the issue.