Explanation: The minimum no. of electron gained or losed to complete the outermost orbit by any elemnt is called its valency. Here, hydrogen already have 1 electron and it needs 1 more electron to complete its outer orbit. Therefore its valency is 1. HOPE IT HELPS YOU!!!
According to the Aufbau principle, the electrons of an atom occupy quantum levels or orbitals starting from the lowest energy level, and proceeding to the highest, with each orbital holding a maximum of two paired electrons (opposite spins). Electron shell #1 has the lowest energy and its s-orbital is the first to be filled.
What can happen is that the two atoms can share their electrons. At the atomic level, this sharing is represented by the electron orbitals (sometimes called electron clouds) overlapping. The two electrons (one from each hydrogen atom) “belong” to both atoms. Each hydrogen atom feels the effect of the two electrons; each has, in a way, filled its valence energy level. A covalent bond is formed.
The electrons like to be in separate shells/orbitals. Shell number one can only hold 2 electrons, shell two can hold 8, and for the first eighteen elements shell three can hold a maximum of eight electrons. As you learn about elements with more than eighteen electrons you will find that shell three can hold more than eight.
• An atom is the basic building block of matter. • All objects are made of atoms. The air, your desk and all living things are made of atoms. • Atoms are EXTREMELY small.
The k ‘th shell can contain up to 2 k 2 electrons, that is, 2 electrons in the first shell (K shell). This is due to the Pauli Exclusion Principle. This is due to the Pauli Exclusion Principle. In the base state of an atom, electron shells are filled from the lowest to the highest orbital - only the highest orbital may not be filled to its limit, the lower ones are completely filled.
A maximum of only two electrons can occupy any one orbital at any one time. According to Bohr , electrons have fixed levels of energy; so, all electrons with the same amount of energy must occupy the same zone, or energy level, or electron shell around the atomic center.
The electron cloud is an imaginary picture of the electron changing its position rapidly over time; it does not mean that an electron is a diffuse cloud of charge. The element after hydrogen is helium (He; Z = 2), the first with atoms having more than one electron.
However, the exception is Helium, the first noble gas, which only has two valence electrons. 8 valence electrons are needed on the 2nd and 3rd valence shells for any molecule to become stable.