Activity of iron and aluminum

This post was last edited by qugd on 2023-12-13 at 21:43. The original poster is using middle school chemistry knowledge to discuss the reactivity of metals, which is a one-sided approach. In the metallic activity of elements, the arrangement of their outermost electrons is just one of the influencing factors; it is not a necessary condition, let alone a sufficient or necessary condition. Factors that affect the reactivity of metals include the first ionization energy, electronegativity, the arrangement of electrons in the outermost and penultimate shells, as well as thermodynamic factors such as electrochemical potential. Below is the electron configuration of the elements in the transition metals of the fourth period. These elements all have only 1 or 2 electrons in their outermost shell, but their reactivity is lower than that of aluminum. Therefore, the example you mentioned is not appropriate; especially for the elements in group 8, the order of their reactivity is even more unusual – the higher the period number, the lower the reactivity of the elements. For instance, iron, cobalt, and nickel are highly reactive metals, whereas osmium, iridium, and platinum are very unreactive metals. The same is true for copper, silver, gold, zinc, cadmium, and mercury. The criteria you use to determine metal reactivity are themselves incomplete and inappropriate.

The reactivity of a metal refers to its ability to release electrons when it reacts with other substances. Although iron (Fe) has 2 electrons in its outermost shell and aluminum (Al) has 3, it is not only the number of electrons in the outermost shell that determines a metal’s reactivity; the interaction forces between the metal atoms and these outermost electrons also play a role, namely the attraction exerted by the metal atom’s nucleus on the electrons, as well as the arrangement of electrons within the atom. Aluminum is a relatively active metal; it appears before iron in the series of metal activity. This is because aluminum is an element in Group 3 of the periodic table, with an electron configuration of \(1s^2 2s^2 2p^6 3s^2 3p^1\). Aluminum atoms easily lose their three outer electrons to form \(Al^{3+}\) ions. Although it loses a large number of electrons, the effective nuclear charge of an aluminum atom is low, resulting in a relatively weak nuclear attraction on its outer electrons; therefore, its ability to lose electrons is relatively strong. On the other hand, iron is a transition metal with an electron configuration of \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 4s^2\). Due to the high effective nuclear charge of the iron nucleus, the interaction between the electrons in its inner \(3d\) orbitals and the nucleus is stronger; this reduces iron’s ability to lose the 2 electrons in its outer \(4s\) orbitals compared to aluminum’s ability to lose electrons. In general, the degree of metallic activity is determined by the nuclear charge, the shielding effect of inner electrons, and the energy levels of outer electrons. Although iron has fewer outer electrons than aluminum, aluminum’s nucleus exerts a weaker attraction on its outer electrons, making it easier for aluminum to lose electrons; therefore, aluminum is more reactive than iron. .

This question is a bit off-topic; it seems that inorganic chemistry in the first year covers knowledge about electronic activity. Chemical engineering courses mainly focus on areas such as process engineering; specialized fields may also cover this subject. Chemical engineering tends to be an engineering application technology developed based on properties, with little overlap with such fundamental theoretical knowledge. According to the periodic table, aluminum belongs to Group 3, while iron belongs to Group 8. Sub-families are more complex than main families, and regular courses cover little about sub-families