Electron Shells and Valency

Also called

electron shells · K L M shells · Bohr model of the atom · valency · valence electrons · octet · duplet · electronic configuration · sodium 2 8 1 · chlorine 2 8 7 · neon 2 8 · argon 2 8 8 · noble gas · outermost shell · इलेक्ट्रॉन कोश · संयोजकता · परमाणु संरचना

Topics

• Electrons fill the shells K, L and M in order; in a Class 9 atom they hold at most 2, 8 and 8 electrons.
• A shell starts filling only when the one inside it is full, and the outermost shell never holds more than 8.
• Sodium (2, 8, 1) has one outer electron, which it gives away easily, so its valency is 1.
• Chlorine (2, 8, 7) is one electron short of 8, so it gains one; its valency is also 1.
• Neon (2, 8) has a full outer shell: it neither gains nor loses electrons, so its valency is 0.
• Valency is the number of electrons an atom gives, takes or shares to reach a full outer shell of 8 (an octet).
• Magnesium (2, 8, 2) gives two electrons, so its valency is 2; oxygen (2, 6) takes two, so its valency is 2.
• A neutral atom has as many electrons as protons; the atomic number tells you how many electrons to place.

About this model

A GLB file of about 213 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

More in Science

1

1 m reflecting telescopeClass 6–123D model

1 m reflecting telescopeClass 6–123D model

A

Action and ReactionClass 93D model

Action and ReactionClass 93D model

Anatomy of a CometClass 5–93D model

Animal and plant cellClass 8–12Interactive lab