Positive Ions (Cations)

* Loss of Electrons: An atom becomes a positive ion when it loses one or more electrons. Electrons carry a negative charge, so removing them leaves the atom with a net positive charge.

* Example: A sodium atom (Na) has 11 protons and 11 electrons. When it loses one electron, it becomes a sodium ion (Na+), with 11 protons and 10 electrons.

Negative Ions (Anions)

* Gain of Electrons: An atom becomes a negative ion when it gains one or more electrons. Adding electrons creates a surplus of negative charge.

* Example: A chlorine atom (Cl) has 17 protons and 17 electrons. When it gains one electron, it becomes a chloride ion (Cl-), with 17 protons and 18 electrons.

Why Atoms Form Ions

Atoms form ions to achieve a stable electron configuration, similar to the noble gases. Noble gases are very unreactive because they have a full outer shell of electrons.

* Octet Rule: Many atoms strive to have eight electrons in their outermost shell (except for hydrogen and helium, which only need two).

* Electrostatic Attraction: Positive ions (cations) and negative ions (anions) are attracted to each other due to electrostatic forces, forming ionic bonds.

Key Points

* Ions are atoms that have gained or lost electrons.

* Positive ions are called cations, and negative ions are called anions.

* Ions are fundamental to the formation of ionic compounds.

Let me know if you have any other questions!