To achieve noble gas configuration, Bromine must gain one electron. In doing so, it obtains the electron configuration of Krypton. Its new complete electron configuration would be: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6.
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Krypton is a noble gas and need not lose electrons. It is already stable.
Oxygen should gain 2 electrons to achieve noble gas configuration
An atom of nitrogen needs 3 more electrons to achieve a stable, noble gas electron configuration. This would give nitrogen a total of 8 valence electrons, making it isoelectronic with a noble gas (in this case, neon).
Calcium has to lose 2 electrons to form noble gas configuration.
Seven electrons should be added to attain the higher noble gas configuration.
Krypton is a noble gas and need not lose electrons. It is already stable.
Oxygen should gain 2 electrons to achieve noble gas configuration
They should gain 2 electrons to attain noble gas electronic configuration. (it doesn't become a noble gas as the number of protons are not same)
4 but it will need energy, so carbon gain 4 electrons to achieve a noble gas configuration.
An atom of nitrogen needs 3 more electrons to achieve a stable, noble gas electron configuration. This would give nitrogen a total of 8 valence electrons, making it isoelectronic with a noble gas (in this case, neon).
An atom with atomic number n needs to gain enough electrons to have the same number of electrons as the nearest noble gas in the periodic table. This would typically involve gaining 8 electrons to achieve the stable electronic configuration of a noble gas.
Calcium has to lose 2 electrons to form noble gas configuration.
Seven electrons should be added to attain the higher noble gas configuration.
An atom of silicon needs to gain 4 electrons in its 3p sublevel to attain the noble gas electron configuration of argon, the noble gas in period 3 of the periodic table.
A species (element, cation or anion) should have eight valence electrons to have a noble gas electronic configuration. However element upto atomic number 4 may have 2 valence electrons and attain the electronic configuration of helium noble gas.
4
There are six electrons in two shells.In order to stable carbon, it take electrons from nearest noble gas to stable the carbon.It order to stable carbon it gain -4 electrons from the nearest noble gas Neon.