Modern models suggest that there is not a fixed relationship between the various electrons in a given shell. The electrons conform to a probability model in their positioning. [And this may go a little way to explaining radioactivity?]
The element with the electron arrangement 2-8-7 is fluorine, which has the atomic number 9. Fluorine has 9 electrons, arranged as 2 in the first energy level, 8 in the second energy level, and 1 in the third energy level.
The element with an electron arrangement of 2, 8, and 7 is fluorine (F), which has 9 electrons. The first energy level can hold a maximum of 2 electrons, the second level can hold a maximum of 8 electrons, and the third level can hold a maximum of 7 electrons for a total of 17 electrons in its neutral atom.
Phosphorus
The number and arrangement of electrons in the outer energy level determine the atom's chemical properties, including its reactivity and ability to form bonds with other atoms. This outer energy level is known as the valence shell.
The electronic arrangement of chlorine is 2, 8, 7. This means that chlorine has 2 electrons in its first energy level, 8 electrons in its second energy level, and 7 electrons in its outermost energy level.
The electron configuration of sulfur is: [Ne]3s23p4.
This element is likely phosphorus (P), which has 15 electrons in total. With 5 electrons in the second energy level, phosphorus has 2 energy levels: the first energy level with 2 electrons and the second energy level with 5 electrons.
Negatively charged particles in the outermost energy level of an atom are called electrons. Electrons are responsible for forming chemical bonds with other atoms to create molecules. The number and arrangement of electrons in the outermost energy level determine the chemical properties of an element.
The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for element to element and generally corresponds to the period number in which the element is present
It has the same electron configuration as in a neon atom.
The electron arrangement of boron is 2 electrons in the first energy level and 3 electrons in the second energy level. The electron configuration of boron is 1s2 2s2 2p1.
The element in period 3 with 8 electrons in its outermost energy level is chlorine (Cl).