Determine the number of valence electrons in each element. Which elements do you expect to lose electrons in chemical reactions? Which do you expect to gain electrons? a. Al b. Sn c. Br d. Se

Key Concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining how an element interacts chemically. The number of valence electrons influences an element's reactivity, as these electrons are involved in forming bonds with other atoms. For main group elements, the number of valence electrons corresponds to their group number in the periodic table.

Electron Loss and Gain

Elements tend to lose or gain electrons to achieve a stable electron configuration, often resembling that of the nearest noble gas. Metals, such as aluminum (Al) and tin (Sn), typically lose electrons to form positive ions, while nonmetals, like bromine (Br) and selenium (Se), usually gain electrons to form negative ions. This behavior is driven by the desire to minimize energy and achieve stability.

Periodic Trends

Periodic trends refer to the predictable patterns observed in the properties of elements as you move across or down the periodic table. For instance, electronegativity and ionization energy generally increase across a period and decrease down a group. Understanding these trends helps predict how elements will behave in chemical reactions, including their tendency to lose or gain electrons.