GENERAL KNOWLEDGE

Detailed explanation-1: -This means that the second shell can hold a maximum of eight electrons (2+6=8). Notice that there are eight elements in the second row of the periodic table. It is only the electrons in the outer-most shell, called the VALENCE shell, that tend to react (be gained, lost, or shared).

Detailed explanation-2: -After the first energy level contains 2 electrons (helium), the next electrons go into the second energy level. After the second energy level has 8 electrons (neon), the next electrons go into the third energy level.

Detailed explanation-3: -The first shell (closest to the nucleus) can hold two electrons. The second shell can hold 8 electrons. The third shell can hold 32 electrons. Within the shells, electrons are further grouped into subshells of four different types, identified as s, p, d, and f in order of increasing energy.

Detailed explanation-4: -Each shell can contain only a fixed number of electrons: the first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons.

Detailed explanation-5: -Period 2 elements (carbon, nitrogen, oxygen, fluorine and neon) obey the octet rule in that they need eight electrons to complete their valence shell (lithium and beryllium obey duet rule, boron is electron deficient.), where at most eight electrons can be accommodated: two in the 2s orbital and six in the 2p subshell.