Atoms can complete their set of valence electrons by either taking some from another element (ionic bond), or by sharing valence electrons with another element (covalent bond).
An ionic bond is usually between a non-metal and a metal, and a covalent bond is usually between two non-metals.
An atom becomes stable when it has a complete set of electrons in its outermost energy level, known as a full valence shell. Atoms achieve stability by gaining, losing, or sharing electrons to reach this state. Once achieved, the atom is less likely to react with other atoms to form chemical bonds.
They will gain 3 electrons from something with 3 valence electrons.
If you're asking how will an atom with 5 valence electrons will achieve a full set of valence electrons, then the answer would be that they bond with other atoms to gain a full set of the valence electrons by sharing or gaining 3 electrons.
Every transition metal has a different number of electrons, they go from 21-30 electrons, then 39-48 elctrons, then 71-80 electrons, and 103-112 electrons.
Noble gases have a complete set of valence electrons in their outermost energy level, which is why they are known to be stable and unreactive.
An atom with 5 electrons in its second energy level will form 3 covalent bonds. These atoms are "trivalent." Nitrogen, for example, has 7 electrons, two in the first energy level, and five in the second. There are 3 bonding pairs of electrons and one set of unpaired electrons. Ammonium (NH3+) is one example.
An element that does not require eight electrons for a full set of valence electrons is represented by the element symbol B. Boron only needs six electrons to complete its valence shell and achieve stability.
If I recall correctly, it's because they don't have any electrons in their atoms. Atoms react in order to get a full set of 8 electrons, and the less electrons an atom has, the more likely they are to react.
The octet rule.
This is called an "octet" of electrons. It could also be called a "closed shell", since it is characteristic of the outer shell of noble gas atoms.
Metals typically do not have half a set of valence electrons; instead, they tend to have one to three electrons in their outermost shell, which they can lose easily to form positive ions. This characteristic contributes to their conductivity and malleability. In contrast, nonmetals often have more than half of a complete set of valence electrons and typically gain or share electrons during chemical bonding.
Atoms tend to achieve stability by filling their outer shell with electrons, typically aiming for a full set of eight electrons, known as the octet rule.