what is the maximum number of electrons in the first energy shell of an atom
two electrons
title: Electron shell text: can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the "n"th shell can in principle hold up to 2("n") electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may title: Energy level text: fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the "n"th shell can in principle hold up to 2("n") electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may have two or even title: Electron configuration text: shells and subshells despite the advances in understanding of the quantum-mechanical nature of electrons. An electron shell is the set of allowed states that share the same principal quantum number, "n" (the number before the letter in the orbital label), that electrons may occupy. An atom's "n"th electron shell can accommodate 2"n" electrons, "e.g." the first shell can accommodate 2 electrons, the second shell 8 electrons, the third shell 18 electrons and so on. The factor of two arises because the allowed states are doubled due to electron spin—each atomic orbital admits up to two otherwise identical electrons with opposite title: Electron shell text: can overlap (see "valence shells" and "Aufbau principle"). Each subshell is constrained to hold electrons at most, namely: Therefore, the K shell, which contains only an subshell, can hold up to 2 electrons; the L shell, which contains an and a , can hold up to 2 + 6 = 8 electrons, and so forth; in general, the "n"th shell can hold up to 2"n" electrons. Although that formula gives the maximum in principle, in fact that maximum is only "achieved" (by known elements) for the first four shells (K, L, M, N). No known element has more than 32 title: Electron shell text: principle. However, there are a number of exceptions to the rule; for example palladium (atomic number 46) has no electrons in the fifth shell, unlike other atoms with "lower" atomic number. Some entries in the table are uncertain, when experimental data is unavailable. (For example, the elements past 108 have such short half-lives that their electron configurations have not yet been measured.) Electron shell In chemistry and atomic physics, an electron shell, or a principal energy level, may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the