Valence Electrons

[Kaitlin Joya 1I]

I'm still unclear on how you know the amount of valence electrons an element has? During lecture, it looked like Professor Lavelle could just determine it by looking at the periodic table, but I'm not sure how he did so.

[Zinnia Kwan 3D]

To calculate valence electrons, all you have to do is count the amount of electrons in the outermost shell, or the number of elements in the row. For example, we for oxygen, counting left to right we would get 6, so there are 6 valence electrons. Do not include f or d block orbitals because they are usually in the shell below the outmost one. For example, gallium only has three valence electrons.

[Preston Pham 2H]

An easy way to tell how many valence electrons there are is to look at the electrons in the outermost shell. For example oxygen's outermost subshell is 2 which consists of 2s and 2p. You add up those electrons and there are your valence electrons. However, it gets a bit harder to tell when there are 3d and 4f involved. We learned in lecture that unless the 4s were occupied with two electrons than it would have more energy than the 3d orbital. Thus if you wanted to calculate the valence electrons you would calculate the ones in the 4s state and ignore the 3d state.

[Molly Smith 1J]

The number of valence electrons is the number of electrons in the highest energy level, n, of an electron's electron configuration. To clarify, let's say we have Oxygen. The electron configuration is (1s^2)(2s^2)(2p^4). The highest energy level, or n, of oxygen is n=2. Therefore, the number of valence electrons equals the number of electrons in the n=2 energy level in oxygen. So, there would be 6 valence electrons (because 2+4 =6). I hope this helps.

[505734174]

Elements in the same group have the same number of valence electrons. Group 1 has 1 e-, group 2 has 2 e-, group 15 has 3 e-, group 16 has 4 e-, group 17 has 5 e-, group 18 has 6 e-, group 19 has 7 e-, and group 20 has 8 e-.

[Maham Kazmi 2J]

For some context, valence electrons are the number of electrons on the atom's outer shell. In terms of determining in directly from the periodic table, I like to think of it as the valence count being the same as the atom's group number. For example, Sodium is Group 1A and has 1 valence electron. Oxygen is group 6A and therefore has 6 valence electrons. It's a quick way to know how many most atoms have and will serve quite useful for drawing Lewis Structures. Hope that helped!

[805401611]

We are able to determine the number of valence electrons that are in a compound by seeing which group the element is in. If you can determine each group's number of valence electrons, then you can determine the valence electrons for an element part of a specific group. For example, Group 1 has 1 valence electron, Group 2 has 2, and so forth until Group 7, which as 7 valence electrons. We exclude the transition metals though in this rule (but most transition metals have 2 valence electrons, fyi). Hope that helps!

[Naomi Christian 1E]

The number of valence electrons refers to how many electrons are in the atom's outermost shell. This shell would be the highest number of n. For example, if an electron has an electron configuration of 1s2 2s2 2p3, then the outermost shell would be n=2. You would count how many electrons are in this shell, so 2 from 2s+3 from the 2p=5 valence electrons.

[Charlie Sjogren-Black]

The number of valence is the number of electrons more than the previous noble gas.

[305749341]

Electron configuration can be determined by the looking at the periodic table. Valence electrons can be deciphered by looking at the electron configuration. That is why looking at periodic table can tell you the valence electrons. The valence electrons are the electrons in the outermost shell. The outermost shell are the s and p orbitals in the highest principle quantum number for the given electron configuration. An s orbital can have a maximum of two electrons and a p orbital can have a maximum of 6 electrons. Therefore, the most amount of valence electrons in the outermost shell is 8 electrons.

[Arjun_Anumula_3E]

Usually, we can calculate the valence electrons by looking at the s and p orbitals. So Dr. Lavelle just counts across a period and skips over the f and d blocks, to count the number of electrons that would be in the outermost shell.

[Hailey Sarmiento 3E]

You can determine the number of valence electrons an atom has by counting across a row or period. Elements on the second period have valence electrons in the second shell: Li has 1 valence electron, Be has 2 valence electrons, and so on.

[Fiona H 2E]

For neutral atoms, the number of valence electrons is equal to the atom's main group number. The main group number for an element can be found from its column on the periodic table. Carbon is in group 4, and it has 4 valence electrons. Oxygen is group 6, and it has 6 valence equations.