periodic table with charges and valence electrons

We are now going to talk about valence electrons, and non-valence electrons, whichĪre known as core electrons and so one question that you Once you reach the fourth period and the transition metals they follow an 18 electron rule of stability, but it's the same idea as before in that they are attempting to fill their valence electron shells in order to become stable. This octet rule holds for elements in the second and third periods (or rows) of the periodic table. This need to gain a filled valance electron shell by having 8 valence electrons is known as the octet rule and explains why certain elements are stable or unstable despite being electrically neutral.

Neon has 8 valence electrons which is a filled second electron shell and is therefore stable and will be unreactive since it does not need to take electrons from other atoms. And again this can be explained by neon's valence electron configuration which is: 2s^(2)2p^(6). Now if we take a neutral atom of neon, Ne, which is just to the right of fluorine, neon is practically the opposite of fluorine in terms of reactivity despite both being neutral atoms. In other words, it will react in such a way to gain a new electron and fulfill its valence shell. And since it's so close to being filled, it will desperately want an extra electron which it will take from any nearby atom to do so. But fluorine has 7 valence electrons, 1 away from being filled. The second electron shell holds a maximum of 8 electrons and 8 electron would be considered a filled valence shell and would therefore be stable and unreactive. And this is explained if we look at fluorine's valence shell (the second shell) electron configuration: 2s^(2)2p^(5). For instance, if we take an atom of fluorine, F, in it's neutral state it has no net charge however it is VERY reactive. So even if an atom is neutral, that is not necessarily its most stable state. And vise versa, something which is unstable is reactive and will engage in chemical reactions to reach a new state. Stability meaning that something is unreactive, that it won't engage in some kind of chemical reaction to reach a new state. The valence shell meaning the outermost electron shell. Thus, the two electrons in the carbon 2 p orbitals have identical n, l, and m s quantum numbers and differ in their m l quantum number (in accord with the Pauli exclusion principle).So being stable when talking about valence electrons means that the valence shell has been filled completely (or half filled). The orbitals are filled as described by Hund’s rule: the lowest-energy configuration for an atom with electrons within a set of degenerate orbitals is that having the maximum number of unpaired electrons. We now have a choice of filling one of the 2 p orbitals and pairing the electrons or of leaving the electrons unpaired in two different, but degenerate, p orbitals. The remaining two electrons occupy the 2 p subshell.

Four of them fill the 1 s and 2 s orbitals. When drawing orbital diagrams, we include empty boxes to depict any empty orbitals in the same subshell that we are filling.Ĭarbon (atomic number 6) has six electrons. There are three degenerate 2 p orbitals ( m l = −1, 0, +1) and the electron can occupy any one of these p orbitals. Because any s subshell can contain only two electrons, the fifth electron must occupy the next energy level, which will be a 2 p orbital. The n = 1 shell is filled with two electrons and three electrons will occupy the n = 2 shell. The fourth electron fills the remaining space in the 2 s orbital.Īn atom of boron (atomic number 5) contains five electrons. Thus, the electron configuration and orbital diagram of lithium are:Īn atom of the alkaline earth metal beryllium, with an atomic number of 4, contains four protons in the nucleus and four electrons surrounding the nucleus.

Periodic table with charges and valence electrons