How do valence electrons determine chemical reactivity? | Socratic
In chemistry, a valence electron is an outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. . energy gap between a valence band (which contains the valence electrons. The number of electrons in an atom's outermost valence shell governs its bonding behaviour. That is why elements whose atoms have the. An atom with a closed shell of valence electrons (corresponding to an electron ion), or to share valence electrons (thereby forming a covalent bond). of the elements, lines between two elements, sometimes called bonds.
For example, manganese Mn has configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d5; this is abbreviated to [Ar] 4s2 3d5, where [Ar] denotes a core configuration identical to that of the noble gas argon.
In this atom, a 3d electron has energy similar to that of a 4s electron, and much higher than that of a 3s or 3p electron. The farther right in each transition metal series, the lower the energy of an electron in a d subshell and the less such an electron has the properties of a valence electron. Thus, although a nickel atom has, in principle, ten valence electrons 4s2 3d8its oxidation state never exceeds four.
For zincthe 3d subshell is complete and behaves similarly to core electrons. Because the number of valence electrons which actually participate in chemical reactions is difficult to predict, the concept of the valence electron is less useful for a transition metal than for a main group element; the d electron count is an alternative tool for understanding the chemistry of a transition metal.
Valence chemistry The number of electrons in an atom's outermost valence shell governs its bonding behavior. Therefore, elements whose atoms can have the same number of valence electrons are grouped together in the periodic table of the elements. As a general rule, a main group element except hydrogen or helium tends to react to form a closed shellcorresponding to the electron configuration s2p6.
This tendency is called the octet rulebecause each bonded atom has eight valence electrons including shared electrons. The most reactive kind of metallic element is an alkali metal of group 1 e. An alkaline earth metal of Group 2 e. Within each group each periodic table column of metals, reactivity increases with each lower row of the table from a light element to a heavier elementbecause a heavier element has more electron shells than a lighter element; a heavier element's valence electrons exist at higher principal quantum numbers they are farther away from the nucleus of the atom, and are thus at higher potential energies, which means they are less tightly bound.
A nonmetal atom tends to attract additional valence electrons to attain a full valence shell; this can be achieved in one of two ways: An atom can either share electrons with a neighboring atom a covalent bondor it can remove electrons from another atom an ionic bond.
The most reactive kind of nonmetal element is a halogen e. Such an atom has the following electron configuration: To form an ionic bond, a halogen atom can remove an electron from another atom in order to form an anion e.
To form a covalent bond, one electron from the halogen and one electron from another atom form a shared pair e. Within each group of nonmetals, reactivity decreases with each lower rows of the table from a light element to a heavy element in the periodic table, because the valence electrons are at progressively higher energies and thus progressively less tightly bound.
In fact, oxygen the lightest element in group 16 is the most reactive nonmetal after fluorine, even though it is not a halogen, because the valence shell of a halogen is at a higher principal quantum number. Neon is one S two, two S two, two P six, that's what this represents and then to get to sodium, you would then have three S one.
How many Valence electrons does sodium have? Well its highest energy, furthest out electron or I say the electron that's in a non-stable shell. That's in a shell that hasn't been stabilized.
It hasn't gotten to its fully stable state. There's only one electron in that situation right over here, the three S one electron. Sodium as well, you could depict like that.Finding the Number of Valence Electrons for an Element
It only has one Valence electron that's the electron that could be swiped away from it or that somehow could be involved in a covalent bond somehow. Now let's do things with more, more Valence electrons than hydrogen or sodium but the important thing to realize and actually for the example of hydrogen sodium is that all of these group one elements are going to have one Valence electron.
They're going to have one electron that they tend to use when they are either getting lost to form an ion or that they might be able to use to form a covalent bond. Now let's think about helium and helium's an interesting character because all of the rest of the noble gases have eight Valence electrons which makes them very stable but helium only has two Valence electrons. The reason why it's included here is because helium is also very stable because for that first shell, you only need two electrons to feel full, to feel stable.
Helium has two Valence electrons, its electron configuration is one S two. Once again the reason why it's out here with the noble gases is because it's very stable and very inert like the noble gases that's why we now use those helium for balloons instead of hydrogen. It's not going to blow up like the Hindenburg but you might say, well, if it has two Valence electrons maybe it should be in group two because wouldn't all of the group two elements have two Valence electrons?
How do valence electrons affect chemical bonding?
That actually would be a very reasonable argument and we've seen that already. One can make a very reasonable argument to put helium in group two for that reason. All of the elements in group two are going to have two Valence electrons. Now, let's jump to one of the most interesting and versatile elements in the periodic table, the one that really forms the basis of life as we know it, and that's carbon.
I encourage you to pause this video and based on what we've just talked about, think about how many Valence electrons carbon has and what its Lewis dot structure could look like.
Well carbon's electron configuration is going to be the same as helium plus you're going to have two S two and then two P two. How many electrons does it have in its outer most shell that has not been completed yet? Well it has these four, two plus two. We could depict them as one, two, three, four Valence electrons.
Why is this interesting? Well we can now think about especially if we see carbon's Valence electrons and we see hydrogen is this Lewis dot structure, we can begin to predict what types of molecules carbon and hydrogen could form together.
How do valence electrons affect bonding? | Socratic
For example, carbon would like to get to A, it would like to pretend like it has electrons so it feels more stable like the noble gas neon and hydrogen would like to at least feel like it has two electrons in its outer most shell so it can feel more stable like helium. If these are carbon atoms and if these are hydrogen atoms, I'll do the hydrogen orange. Actually let me do it this way.
Hydrogen, hydrogen, hydrogen and actually let me do it the way I was doing it first. You could imagine something like this where carbon could bond just based on what we've learned about Valence electrons and Lewis dot structures. You could say, well, I would predict that maybe a molecule like this could form where a carbon shares it's four Valence electrons with four different hydrogens and in exchange it shares an electron from each of those four hydrogens and so the carbon can feel like it has eight Valence electrons.
Each of the hydrogens can feel like it has two Valence electrons. If you did this, if you say, "Well there should be some molecule out there" "in nature that seems pretty stable like this. This is methane and the way that this would be depicted with the Lewis dot structure is this right what I did over here is less conventional notation.
1.3: Valence electrons and open valences
Each of these electron pair so that electron pair would be represented as a covalent bond. This would be represented as a covalent bond. That would be represented as covalent bond. That would be represented as a covalent bond.
Each of these bonds or the sharing of essentially two electrons, the two electrons. Carbon can feel like it has two, four, six, eight electrons even it's sharing.
Each of the hydrogens can feel like they have two electrons which gets it into a more stable state. In any of the elements, in carbon's group, they are all going to have four Valence electrons.