Valence Electrons of Elements - Video Tutorials & Practice Problems
Get help from an AI Tutor
Ask a question to get started.
The Valence Electrons represent the outer shell electrons of an element or ion.
Valence Electrons
1
concept
Valence Electrons of Elements
Video duration:
2m
Play a video:
Now when it comes to valence electrons we're gonna say that for main group elements, so basically not the transition metals, we're gonna say the number of valence electrons equals the group number of the element. And when we say valence electrons, the valence electrons are just your outer shell electrons involved in forming chemical bonds. The inner core electrons are just all the remaining electrons that are not valence electrons. And we're going to say here that your atomic number can be thought of as as your total number of electrons, and that equals just all your valence electrons plus your inner core electrons. If we take a look here, we have chlorine. Chlorine is in group 7 a, so it has 7 valence electrons. Its electron configuration is 1 s 2, 2 s 2, 2p63s23p5. Here remember the number in front tells us the shell number. So here this would be shell 1, shell 2, and shell 3. If we have a representation of the atom like we do here, the first shell has 2 electrons in it. The second shell n equals 2 has a total of 8 electrons in it. So if you count 1, 2, 3, 4, 5, 6, 7, 8, all the way around. And then we can say here that the outer shell has 7 electrons total in it. So let's add the additional 2 electrons that we need. So we have 1, 2, 3, 4, 5, 6, and then 7. Those are our 7 total electrons. So here we have the visual representation of the atom, we're using the electron configuration to justify this representation of the chlorine atom, but for simplicity just say group number of the element, main group element is 7 a, so it has 7 valence electrons. If you subtract that, then what's left will be your inner core electrons, which would just be 10. And we would see, yes, in fact it is 10 because when you add up these numbers it gives you 10, and when you look at the visual representation of the chlorine atom, you'd also see that there are 10 inner core electrons.
2
example
Valence Electrons of Elements Example 1
Video duration:
1m
Play a video:
Here it says, how many inner core and valence electrons would a would a silicon atom possess? So atom means that it's a neutral element, and when we look, silicon has an atomic number of 14 on the periodic table. So remember, your atomic number, which is connected to your total number of electrons equals your valence electrons, which for main group element is just your group number, plus your inner core electrons. Here, the atomic number, again, we said is 14. Silicon is in group 4 a on the periodic table. Since it's in group 4 a, it has 4 valence electrons. So we already know we have 4 valence electrons. And all we have to do here to find the number of inner core electrons is subtract 4 from both sides, and what's left is 10. That 10 would equal the number of inner core electrons. So we'd say that's the silicon atom has 4 valence electrons in single group 4 a, and it has 10 inner core electrons.
3
concept
Valence Electrons of Elements
Video duration:
2m
Play a video:
Now with transition metals, we're going to say the number of valence electrons equals their outermost s orbital electrons plus their d orbital electrons. And here, remember your transition metal elements are known as your group b elements. So we know there's 3 b all the way to, 1 b all the way to 8 b, but you don't look at that to determine the number of valence electrons. Let's take a look. Here I've listed the outermost s orbitals and the d orbital electrons for each of the transition metals. If we look at them, this is 2 +1 which is 3, 2+2 which is 4, and it goes on and on. And then when we get to zinc we see that it is 2 +10 which is 12. Remember, besides classifying transition metals as group b elements, if you look at a full out elect periodic table that we did in later in earlier chapters, you'll see that these groups also have another set of numbers for their group identity. This would be group 3, group 4, 5, 6, 7, 8, 9, 10, 11, and 12. Remember, our main group elements, groups 1 a to 8 a, but they also have another set of numbers that describe them. Group 1 a is group 1, group 2 a is group 2, group 3 a is group 13, all the way to group 18 for group 8 a. Okay? So just remember, if you're looking at the full out periodic table that I talked about in earlier chapters, you'll know that the transition metals are also represented as groups 3 to 12, and that new group number designation is also equal to the number of valence electrons. So just remember, you could do it the long way where you give the electron configurations of each transition metal and look up the number of total s and d electrons, or you can just remember that the transition metals are represented as groups 3 to 12.
Valence Electrons of Transition Metals = s + d electrons.
4
example
Valence Electrons of Elements Example 2
Video duration:
2m
Play a video:
Here it says, how many valence electrons would the manganese 5 ion possess? So manganese 5 means it has a 5 plus or plus 5 charge. That means that it has lost 5 electrons. So remember, manganese is a transition metal, it is in group 7 of the periodic table. Don't confuse group 7 with group 7 a. Group 7 a are the halogens. Right? But you're talking about group 7 for this man manganese ion. So here for manganese when it's neutral it has 7 valence electrons, but it just lost 5, so we're gonna subtract out 5. So it should have 2 valence electrons left. If you wanted to do it the longer way through the use of the electron configuration, you could also do that. So here we need to find out what the electron configuration is of the neutral manganese. It would be argon4s23d5. Now remember, plus 5 means we would lose 5 electrons, and we lose them from the high shell number first. So we'd lose 2 both of these electrons from 4 s so they'd be completely gone, and we need to lose 3 more to get to plus 5 charge. Those additional 3 would have to come from the 3 d set of orbitals. So when we lose 3 more, we'd have left 2 electrons. Remember, the number of valence electrons for a transition metal is the s+orbitalelectrons. We lost our 4sorbitalelectrons, so all we have left are these 2 d orbital electrons. So whether you do it the long way through the electron configuration, or if you just simply remember the secondary group number for the transition metals is equal to their valence electrons, you'd also find out that you have 2 valence electrons left. So choose the way that you're most comfortable with to get your final answer.
5
Problem
Problem
How many core electrons does the gallium atom possess?
A
2 electrons
B
8 electrons
C
18 electrons
D
24 electrons
E
28 electrons
6
Problem
Problem
Provide the number of valence electrons in the iron (III) ion.
A
2 valence electrons
B
5 valence electrons
C
8 valence electrons
D
3 valence electrons
E
6 valence electrons
7
Problem
Problem
Which of the following have their valence electrons in the same shell?