Alkaline Earth Metals

University:
California State University, Northridge
Course:
CHEM 100 | Principles of Chemistry
Academic year:

2023
Views:

18

Pages:

2
Author:

SMauren

ALKALINE EARTH METALS These alkaline earth metal (IIA) elements consist of Be, Mg, Ca, Sr, Ba, and Ra. This group has characteristics similar to group IA. The difference is that group IIA has an electron configuration ns2 and is a strong reducing agent. Although tougher than the group IA, but group IIA is still relatively soft, shiny silver, and has higher melting point and density. 1. Physical Properties The alkaline earth metal elements are somewhat harder, ranging in hardness from barium which is about as hard as lead, to beryllium which is hard enough to scratch most other metals. This group has a simple electronic structure, alkaline earth metal elements has 2 electrons that are relatively easy to remove. Apart from ionization energy relatively low, the average electronegativity of this group is also low due to the size of the atom and the relatively large distance between the electrons outermost with the core. 2. Chemical Properties Alkaline earth metals experience the same redox reactions as alkali metals, only they release 2 electrons to form 2+ ions. Alkaline earth metals tend to be less reactive than alkali metals because their ionization energy is greater than alkaline earth metals, so the reactivity trend is: Ba > Sr > Ca > Mg > Be. The reactions of alkaline earth metals are as follows. a. Alkaline Earth Metals React with Halogens Alkaline earth metals react with halogens to form halide salts (MX2 ) Reaction: M + X2 MX2 , with: M = Be, Mg, Ca, Sr, Ba b. Alkaline Earth Metals React with Oxygen Alkaline earth metals react with oxygen to form oxides (MO). Reaction:2 M + O2 2 MO, with M = Be, Mg, Ca, Sr, Ba Beryllium and magnesium are not very reactive when reacted with oxygen at room temperature, but they give off a bright white light when burned with a flame. Meanwhile, calcium, strontium and barium are quite reactive so they need to be stored under oil so they don't come into contact with air. Like heavy alkali metals, strontium and barium form peroxide (MO2). c. Alkaline Earth Metals React with Water Alkaline earth metals react with water to form metal hydroxide [M(OH)2 ]. Reaction : M(s) + 2 H2O(l) M2+(aq) + 2 OH–(aq) + H2(g) With M = Mg, Ca, Sr, atau Ba Except for beryllium, all alkaline earth metals react with water to form the metal hydroxide M(OH)2 . Magnesium reacts only if the temperature is above 100 °C, whereas for calcium and strontium, the reaction is slow and at room temperature. Only barium reacts violently.