Which elements are alkaline earth metals? (a) rubidium (b) tungsten (c) magnesium (d) cesium (e) beryllium

The periodic table is a fundamental concept in chemistry, which organizes all known chemical elements in an informative array. The arrangement of the table is based on the atomic number of the elements, which is the number of protons found in the nucleus of an atom. Each row on the table is known as a 'period', and each column is referred to as a 'group'.

Elements in the same group often share similar chemical properties, due to their comparable electron configurations. For instance, alkaline earth metals, which you encountered in the exercise, are located in Group 2 of the periodic table. This group is immediately to the right of the alkali metals in Group 1. Learning how to navigate the periodic table is essential for understanding the relationships between different elements and predicting their behavior in chemical reactions. Moreover, locating elements on the periodic table is the first step in identifying whether a particular element is an alkaline earth metal, as you saw in the exercise solution.

Electron configuration describes the distribution of electrons in an atom or molecule. It's a key aspect in understanding chemical bonding and the properties of elements. Each electron orbits the atom's nucleus within specific regions called orbitals, and these orbitals are divided into sublevels (s, p, d, f).

The most stable electron configuration is one where electrons occupy the lowest available energy levels, following the Aufbau principle. This pattern can be predicted based on the element's position in the periodic table. Referring to the previous exercise, alkaline earth metals have two electrons in their outermost s-sublevel, meaning their electron configuration ends with 's²'. This specific electron arrangement makes these metals reactive, as they tend to lose their two outer electrons to achieve a more stable electron configuration, similar to the nearest noble gas, forming ionic bonds in the process.

Chemical elements are purely composed of one type of atom, distinguished by the number of protons in their nuclei, known as the atomic number. Each element has unique chemical and physical properties, and when elements chemically combine, they form compounds with different characteristics from the elements they comprise.

The exercise under inspection involved identifying alkaline earth metals, a specific category of elements. These are differentiated from others by their valence electron structure and their typical placement in Group 2 on the periodic table. By understanding the qualities that distinguish one element from another, such as atomic number, electron configuration, and positioning on the periodic table, students can begin to predict how an element will interact chemically and the type of compounds it will form.