Respuesta :
Answer:
Explanation:
The column arrangement in the periodic table corresponds with the electron orbitals in which the electrons reside. There are labelled as s, p, d, and f, and have a series of energy shells that correspond to the rows from top (H: 1s) to bottom (Fr: 7s). Within each row are found one or more of the orbitals s, p, d, and f.
The first column has electrons in the s orbital for that energy level. This is the first appearance of any orbital for the indicated energy level. Thus the elements in the first column contain the first electron of a higher energy level for that entire row. This puts it in a position of relative instability as it is always seeking a lower enegy state. Opportunities abound in the world of elements for it to leave the parent atom, e.g. Na, and take up residence in a passing atom that would love an electron, say chlorine, Cl. Showing only the orbitals for the respective energy level, each element in column 1 has its last electron in the first available, higher-energy, orbital.
H: 1s^1
Li: 2s^1
Na: 3s^1
K: 4s^1
Rb: 5s^1
Cs: 6s^1
Fr: 7s^1
That is the life of the outer electron in all the first column elements. All of these elements are willing to lose [happy to lose] this single electron, thus giving the column elements a charge of +1 when the electron leaves.
A similar situation arises for the elements in column 17, the halogens (F, Cl, Br, I,At, Ts). Except all these elements have what is known as a nearly full valence shell of electrons. Cl, for example, is putting electrons into orbitals on the 3rd energy level. For Cl, this consists of the 3s and 3p orbitals. 2 electrons will fit into s orbitals, while 6 will fill the p orbitals.
F: 2s^2 2p^5
Cl: 3s^2 3p^5
Br: 4s^2 4p^5
I: 5s^2 5p^5
Column 17 elements are just 1 electron short of filling the p orbitals. The elements in column 18, the Noble Gases, all have full outer shells of electrons for that energy level. each has a p orbital filled with 6 electrons, the maximum allowed in the p orbitals. So for any one row, electrons are moved into orbitals that are on the outer energy level until all available orbitals are filled, whichj would be the Noble Gas column. Additional electrons would have to move to a higher energy shell after each row is completed.
[This leaves out discussion of the d and f orbitals which become available on row 4 for the columns noted as the Transition Elements.]
When a column 1 element loses an electron, it finds itself in a more stable, lower energy state. All the remaining orbitals are filled (in the energy levels preceding the one for the lone outer electron). This is a lower energy state for that element. Conversely, the halogens, when they gain an electon, are in a more stable state since all of their valence orbitals are now full. So the column 17 elements all exhibit simliar chemical properties and have a -1 valence charge.
Wordy, but true . . .
