A neutral nitrogen atom contains exactly seven electrons. Nitrogen (N) is element number 7 on the periodic table. It is widely distributed, making up about 78% of Earth’s atmosphere as a diatomic gas. Nitrogen is also a fundamental component of all life, found in proteins and DNA.
Determining the Electron Count
The number of electrons in any neutral atom is determined by the atomic number (Z). Nitrogen has an atomic number equal to 7. This number represents the precise count of positively charged protons found within the atom’s nucleus.
For an atom to exist in a neutral state, it must maintain a balance between its positive and negative charges. The negative charge comes from the electrons orbiting the nucleus. Therefore, a neutral nitrogen atom must possess seven negatively charged electrons to perfectly counterbalance the seven positively charged protons.
If the atom were to gain or lose electrons, it would become an ion, carrying an overall electrical charge. In its uncharged state, the count of electrons matches the atomic number of 7.
Electron Arrangement and Shells
Once the total number of seven electrons is established, their placement around the nucleus is governed by principles of energy and space. Electrons occupy distinct regions known as electron shells or energy levels. These shells are filled sequentially, starting with the one closest to the nucleus, which has the lowest energy.
The first shell (K shell) has a maximum capacity of two electrons. Nitrogen’s first two electrons completely fill this innermost layer, forming a stable, closed shell. The remaining five electrons then occupy the next available energy level, the second shell (L shell).
This arrangement results in the nitrogen atom having an electron configuration described as 2, 5. This structure means two electrons are positioned close to the nucleus, and five electrons are further away in the outermost shell. This spatial distribution dictates how the nitrogen atom will interact with other atoms.
How Nitrogen Uses Its Electrons for Bonding
The five electrons in the outermost shell are known as valence electrons. Atoms tend to react in ways that complete their outermost shell, following the Octet Rule. This rule states that atoms are most stable when their outermost energy level contains eight valence electrons.
Because nitrogen already has five valence electrons, it needs to acquire three more to achieve the stable eight-electron configuration. It is much more energetically favorable for nitrogen to gain three electrons rather than lose its existing five. Nitrogen rarely gains electrons outright to form an ion; instead, it typically shares its electrons with other atoms.
This sharing process forms a covalent bond. Nitrogen commonly forms three such bonds because it needs three electrons to complete its shell. For example, in the nitrogen gas molecule (\(N_2\)), two nitrogen atoms share three pairs of electrons, forming a strong triple bond. Ammonia (\(NH_3\)) is another example, where nitrogen forms three single bonds by sharing electrons with three separate hydrogen atoms.