No, O2 does not satisfy the octet rule because as we know octet rule states that an atom has to have 8 e- in the outer shell. Oxygen has 6 valence electrons, the bonds should be 8-6=2 bonds. So we need 2 more covalent bonds to form an octet.
A potassium atom has 1 electron in its outer shell. In order to satisfy the octet rule, it needs to donate 7 electrons to another atom to reach a stable configuration with a full outer shell.
Covalent compounds obey the octet rule by sharing electrons between atoms in order to achieve a full outer shell of electrons, usually 8 electrons. This sharing allows each atom to achieve greater stability by filling its valence shell with the desired number of electrons.
PF5 obeys the octet rule as it has 5 bonding pairs of electrons around the central phosphorus atom, satisfying the octet. Cs2 does not follow the octet rule as Cs is in Group 1 and can only form ionic bonds. BBr3 is an exception to the octet rule as boron has only 6 electrons around it due to the empty d orbital. CO3 2- also obeys the octet rule as each oxygen atom has a complete octet.
Boron atoms do not follow the octet rule. This is because boron typically forms compounds with fewer than 8 electrons around it due to its atomic structure. Boron forms stable compounds by sharing electrons in covalent bonds and can have as few as 6 electrons in its valence shell.
Silicon needs to gain 4 more electrons to have a stable octet. It has 4 valence electrons and aims to have a full outer shell with 8 electrons, following the octet rule.