Lithium is a soft, silvery-white chemical element, often recognized for its role in modern technologies like batteries. Atoms are typically electrically neutral, but they can undergo transformations, gaining or losing charged particles called electrons, to achieve a more stable state. When an atom changes its electron count, it no longer remains neutral, taking on an electrical charge and becoming what is known as an ion.
What Are Ions? Cations and Anions Defined
An ion is an atom or molecule that carries a net electrical charge. This charge arises from an imbalance between the number of positively charged protons within the atom’s nucleus and the negatively charged electrons orbiting it. When an atom loses one or more of its electrons, it forms a positively charged ion called a cation. This occurs because the number of positive protons then exceeds the number of negative electrons, leading to a net positive charge.
Conversely, if an atom gains one or more electrons, it becomes a negatively charged ion known as an anion. In this case, the increased number of negatively charged electrons outweighs the positive charge of the protons, resulting in an overall negative charge.
Lithium’s Atomic Makeup and How It Behaves
Lithium, denoted by the symbol Li, has an atomic number of 3. This means a neutral lithium atom contains three protons in its nucleus and three electrons orbiting it. The arrangement of these electrons, known as its electron configuration, is 1s² 2s¹. This configuration indicates that two electrons occupy the innermost shell, and a single electron resides in the outermost shell.
That lone electron in the 2s orbital is referred to as a valence electron. Atoms tend to react in ways that allow them to achieve a stable electron configuration, typically resembling that of a noble gas. For lithium, which is highly reactive, it is more favorable to lose this single valence electron than to gain seven additional electrons to complete its outermost shell. Losing this electron allows lithium to attain a stable electron arrangement.
The Lithium Ion: A Cation Explained
Based on its atomic structure and behavior, lithium forms a cation. When lithium atoms participate in chemical reactions, they readily lose their single valence electron. This loss of a negatively charged electron means the lithium atom now has three protons but only two electrons. The imbalance results in a net positive charge of +1, forming the lithium ion, symbolized as Li⁺.
The electron configuration of the Li⁺ ion becomes 1s². This configuration is identical to that of the noble gas helium, which is known for its exceptional stability due to its filled electron shell. The lithium ion is a common component in various substances, including lithium carbonate, which has medicinal applications, lithium chloride used as a desiccant, and lithium hydroxide, utilized in air purification systems. It is also the fundamental charged particle enabling the function of lithium-ion batteries.