Final answer:
Lithium (Li) contains three electrons with the first two filling the 1s subshell and denoted by 1s², and the third electron occupying the higher energy 2s subshell, denoted by 2s¹. These electrons determine lithium's chemical properties, and their arrangement follows the principles of quantum mechanics.
Step-by-step explanation:
Arrangement and Location of Subatomic Particles in the Atom
The structure of atoms involves subatomic particles which include protons, neutrons, and electrons. An atom's nucleus contains protons and neutrons, while electrons move around the nucleus. Let's use lithium (Li) as an example. Lithium has three protons, hence it also has three electrons to balance the positive charge.
The arrangement of electrons in an atom follows principles of quantum mechanics where electrons occupy specific energy levels or shells. These shells have subshells denoted by the letters s, p, d, and f. For lithium, with an atomic number of 3, the first two electrons fill the lowest energy level, the 1s subshell. The electron configuration notation for these two electrons is 1s², which indicates two electrons with opposite spins in the 1s orbital.
The third electron in lithium occupies the next lowest energy level, the 2s subshell, which is at a higher energy than the 1s subshell. Therefore, its electron configuration is 1s²2s¹. The superscripts denote the number of electrons in each subshell. These three electrons dictate the chemical properties of the lithium atom, particularly its valency and reactivity.