A valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. The presence of valence electrons can determine the element's chemical properties and whether it may bond with other elements: For a main group element, a valence electron can only be in the outermost electron shell.
An atom with one or two valence electrons more than a closed shell is highly reactive, because the extra valence electrons are easily removed to form a positive ion. An atom with one or two valence electrons fewer than a closed shell is also highly reactive, because of a tendency either to gain the missing valence electrons thereby forming a negative ion , or to share valence electrons thereby forming a covalent bond. Like an electron in an inner shell, a valence electron has the ability to absorb or release energy in the form of a photon.
An energy gain can trigger an electron to move jump to an outer shell; this is known as atomic excitation. Worksheets Worksheets for Kids. Valence Electrons of all the elements in the Periodic Table Valence Electrons of all the elements in the Periodic Table Refer to graph, table and property element trend below for Valence Electrons of all the elements in the periodic table.
Valence Electrons Graph - Valence Electrons of all the elements in graph Mouseover on the chart to see the element name and Valence Electrons of the element. May 21, The valence electrons are found based on where the element is on the periodic table.
Locate the element on the periodic table. This will be how many valence electrons there are. Please note: This will only work for the first 20 elements. Learn how to read an electron configuration. Another way to find an element's valence electrons is with something called an electron configuration. These may at first look complicated, but they're just a way to represent the electron orbitals in an atom with letters and numbers and they're easy once you know what you're looking at.
Let's look at an example configuration for the element sodium Na : 1s 2 2s 2 2p 6 3s 1 Notice that this electron configuration is just a repeating string that goes like this: number letter raised number number letter raised number The number letter chunk is the name of the electron orbital and the raised number is the number of electrons in that orbital — that's it! So, for our example, we would say that sodium has 2 electrons in the 1s orbital plus 2 electrons in the 2s orbital plus 6 electrons in the 2p orbital plus 1 electron in the 3s orbital.
That's 11 electrons total — sodium is element number 11, so this makes sense. Keep in mind that each subshell has a certain electron capacity. Their electron capacities are as follows: s: 2 electron capacity p: 6 electron capacity d electron capacity f: 14 electron capacity.
Find the electron configuration for the element you are examining. Once you know an element's electron configuration, finding its number of valence electrons is quite simple except, of course, for the transition metals. If you're given the configuration from the get-go, you can skip to the next step.
If you have to find it yourself, see below: Examine complete electron configuration for oganesson Og , element , which is the last element on the periodic table. It has the most electrons of any element, so its electron configuration demonstrates all of the possibilities you could encounter in other elements: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6 Now that you have this, all you need to do to find another atom's electron configuration is just fill in this pattern from the beginning until you run out of electrons.
This is easier than it sounds. You only need to change the number in the final orbital — the rest is the same since the orbitals before the final one are completely full. For more on electron configurations, see also this article. Assign electrons to orbital shells with the Octet Rule. As electrons are added to an atom, they fall into various orbitals according to the order given above — the first two go into the 1s orbital, the two after that go into the 2s orbital, the six after that go into the 2p orbital, and so on.
When we're dealing with atoms outside of the transition metals, we say that these orbitals form "orbital shells" around the nucleus, with each successive shell being further out than the ones before.
Besides the very first shell, which can hold only two electrons, each shell can have eight electrons except, again, when dealing with transition metals. This is called the Octet Rule. For example, let's say we're looking at the element Boron B. Since its atomic number is five, we know it has five electrons and its electron configuration looks like this: 1s 2 2s 2 2p 1.
Since the first orbital shell has only two electrons, we know that Boron has two shells: one with two 1s electrons and one with three electrons from the 2s and 2p orbitals. As another example, an element like chlorine 1s 2 2s 2 2p 6 3s 2 3p 5 will have three orbital shells: one with two 1s electrons, one with two 2s electrons and six 2p electrons, and one with two 3s electrons and five 3p electrons.
Find the number of electrons in the outermost shell. Now that you know your element's electron shells, finding the valence electrons is easy: just use the number of electrons in the outermost shell. If the outer shell is full in other words, if it has eight electrons or, for the first shell, two , the element is inert and will not react easily with other elements.
Again, however, things don't quite follow these rules for transition metals. For example, if we're working with Boron, since there are three electrons in the second shell, we can say that Boron has three valence electrons.
Use the rows of the table as orbital shell shortcuts. The horizontal rows of the periodic table are called the element "periods. You can use this as a shortcut to determine how many valence electrons an element has — just start from the left side of its period when counting electrons. Once again, you'll want to ignore the transition metals with this method, which includes groups For example, we know the element selenium has four orbital shells because it is in the fourth period.
Since it is the sixth element from the left in the fourth period ignoring the transition metals , we know that the outer fourth shell has six electrons, and, thus, that Selenium has six valence electrons. Valence electrons can be found by determining the electronic configurations of elements.
Thereafter the number of electrons in the outermost shell gives the total number of valence electrons in that element. Not Helpful 83 Helpful If the atom is not an ion, then we can say that the atom has 33 protons. This means it is element 33, which is arsenic.
Then we know that it is not a transition metal, so we look and find the unit digit of its group number is 5, which means it has 5 valence electrons. Not Helpful 58 Helpful Not Helpful 69 Helpful Atoms gain or lose electrons, negative charges, because the protons have the positive charge and they are held in the nucleus by the strong nuclear force.
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