Three pairs of electrons.
four
Three bonds need to be made, so that's six electrons shared.
Most atoms need eight valence electrons to have a complete outer shell and achieve a stable, "happy" state, a concept known as the octet rule. However, there are exceptions, such as hydrogen and helium, which are stable with just two valence electrons. Atoms tend to gain, lose, or share electrons to reach this stable configuration.
2
5
Fluorine needs one more electron to have a stable octet, as it has 7 valence electrons and stable octet configuration is achieved with 8 electrons.
2
eight
Sulfur needs 2 more electrons to achieve a stable octet, making a total of 8 electrons in its outer shell to achieve a stable electron configuration.
Most atoms require eight electrons in the outer shell to be stable. The exception is atoms that are only filling the s1 orbital, which becomes stable with only two electrons.
Oxygen needs to gain two electrons to achieve a stable electron configuration, which would give it a full outer shell of eight electrons (octet). This can be achieved through forming chemical bonds with other elements.
In a reaction u need two valence electrons to gain or share two valence electrons.