The periodic table organizes chemical elements based on their atomic properties, grouping those with similar characteristics into vertical columns, known as groups. Elements within the same group exhibit comparable chemical behaviors because they possess the same number of electrons in their outermost shell, which are responsible for how an element interacts with others.
Defining Group 2 Elements
Group 2 of the periodic table contains the Alkaline Earth Metals. This specific group includes Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). Each possesses two electrons in its outermost ‘s’ orbital (ns²).
These two valence electrons dictate their chemical behavior. They readily lose them during chemical reactions to achieve a stable, noble gas-like electron configuration. This results in ions with a +2 charge, their most common oxidation state.
Shared Characteristics of Alkaline Earth Metals
Alkaline Earth Metals are typically silvery-white solids that are relatively soft and possess low densities. They are also good conductors of electricity.
While they are reactive, they exhibit less reactivity compared to the Group 1 alkali metals. Due to their reactivity, alkaline earth metals are never found as pure elements in nature, always occurring as compounds. Their reactivity increases down the group, from beryllium to radium.
Several trends are observed in their properties as atomic number increases down the group. The atomic radius, which is the size of the atom, increases from beryllium to radium because additional electron shells are added with each successive element. Conversely, the ionization energy, which is the energy required to remove an electron, decreases down the group. This occurs because the outermost electrons are progressively farther from the nucleus and experience a weaker attractive force.
Their reaction with water also follows a trend: beryllium does not react with water, and magnesium reacts slowly with hot water. However, calcium, strontium, and barium react readily with cold water, producing metal hydroxides and hydrogen gas.
Group 2 Elements in Our World
Alkaline Earth Metals play various roles in both natural systems and human applications. Calcium, for instance, is the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It is also important for proper muscle movement, nerve signal transmission, and blood clotting.
Magnesium is another element with diverse uses. In plants, it forms a central part of the chlorophyll molecule, which is essential for photosynthesis. Magnesium compounds, such as magnesium oxide, are also used in medicine as antacids to relieve indigestion.
Beryllium, known for being very light and stiff, finds use in specialized alloys with copper or nickel. These alloys are utilized in precision instruments like gyroscopes, springs, and electrical contacts, and in aerospace components due to their strength and stability. Its ability to transmit X-rays makes beryllium foil a material for X-ray tubes.
Strontium is widely recognized for its use in pyrotechnics, where its compounds, particularly strontium nitrate, produce the vibrant red color seen in fireworks. Barium compounds are also important in medical diagnostics. Barium sulfate is used in “barium meals” to allow doctors to visualize the digestive tract during X-ray examinations. Radium, a radioactive element, was historically used in luminous paints for watch dials and other glow-in-the-dark applications.