A lithium cation, denoted as Li+, is a lithium atom that has lost one electron. This process results in a positive charge due to the unbalanced number of protons and electrons. In contrast, a neutral lithium atom has three protons and three electrons, making it electrically neutral.
Comparing the two, the most significant difference lies in their electrical charge and behavior. A lithium atom tends to be more reactive because it seeks to lose its outer electron to achieve a stable electron configuration, similar to that of the noble gases. Once it loses this electron, the lithium cation is more stable in certain chemical environments, particularly in ionic compounds. The loss of an electron diminishes its size and alters its properties, making the cation interact differently with other ions and molecules.
In summary, while both forms contain the same number of protons and have similar chemical properties, a lithium cation is positively charged and smaller in size than a neutral lithium atom, influencing its reactivity and interactions in chemical reactions.