How can negative ion form from an atom

For elements in groups 6 and 7, the charge on the ion is equal to 8 minus group number. Sulfur is in group 6 of the periodic table. What is the charge on its ions, and is the charge positive or negative? The charge is negative, since sulfur is a non-metal. The process is motivated by the achievement of more stable electronic configurations, such as the octet rule, which states that most stable atoms and ions have eight electrons in their outermost valence shell.

Polyatomic ions are generally very unstable and reactive. However, according to the octet rule, sodium would be more stable with 10 electrons 2 in its inner most shell, 8 in its outermost shell. Therefore, sodium tends to lose an electron to become more stable. On the other hand, chlorine tends to gain an electron to become Cl —. Chlorine naturally has 17 electrons but it would be more stable with 18 electrons 2 in its inner most shell, 8 in its second shell, and 8 in its valence shell.

Therefore, chlorine will take an electron from another atom to become negatively charged. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Our convention is that if a chemical process provides energy to the outside world, the energy change is negative. If it requires energy, the energy change is positive.

This is the energy released when 1 mol of gaseous ion pairs is formed, not when 1 mol of positive and negative ions condenses to form a crystalline lattice.

Because of long-range interactions in the lattice structure, this energy does not correspond directly to the lattice energy of the crystalline solid. However, the large negative value indicates that bringing positive and negative ions together is energetically very favorable, whether an ion pair or a crystalline lattice is formed.

The observed internuclear distance in the gas phase is pm. Given: cation and anion, amount, and internuclear distance. Asked for: energy released from formation of gaseous ion pairs. The internuclear distance in the gas phase is pm. Likewise, adding an electron to fill a valence shell and achieve noble gas electron configuration is exothermic or only slightly endothermic. To add an additional electron into a new subshell requires tremendous energy - more than the lattice energy.

Thus, we find Cl - in ionic compounds, but not Cl This amount of energy can compensate for values as large as I 3 for valence electrons i. Because most transition metals would require the removal of more than 3 electrons to attain a noble gas core, they are not found in ionic compounds with a noble gas core. A transition metal always loses electrons first from the higher 's' subshell, before losing from the underlying 'd' subshell. The remaining electrons in the unfilled d subshell are the reason for the bright colors observed in many transition metal compounds!

For example, iron ions will not form a noble gas core:. Some metal ions can form a pseudo noble gas core and be colorless , for example:. The valence electrons do not adhere to the "octet rule" in this case a limitation of the usefulness of this rule.

Note: The silver and cadmium atoms lost the 5s electrons in achieving the ionic state. When a positive ion is formed from an atom, electrons are always lost first from the subshell with the largest principle quantum number. If the one electron is added, the Bohr diagrams and Lewis symbols for fluorine and neon are identical.

The octet rule is satisfied. Ion Charge? What is the charge on fluorine as a result of adding one electron? A comparison of the atom and the ion will yield this answer.