Question

in the periodic table, elements in groups 1a through 8a (also known as the representative elements) have specific patterns in their valence electrons - the electrons found in the highest occupied energy level of an atom. these valence electrons play a crucial role in determining how an element will bond and react with other elements. for example, group 1a elements, such as sodium (na) and potassium (k), have one electron in their highest energy level, making them highly reactive as they tend to lose this electron to achieve a stable electron configuration. group 7a elements, like chlorine (cl) and fluorine (f), have seven valence electrons and are reactive as well, often seeking one more electron to complete their outer shell. in contrast, group 8a elements, such as neon (ne) and argon (ar), have a full set of valence electrons (eight), making them very stable and generally unreactive. understanding the relationship between the group number and the number of valence electrons helps predict the chemical behavior and reactivity of these elements.
based on the passage, what is a valence electron, and how does the group number (1a through 8a) help determine the number of valence electrons in representative elements?

Explanation:

The passage defines valence electrons as electrons in the highest occupied energy level. It shows that for groups 1A - 8A (representative elements), the group number (e.g., 1A has 1, 7A has 7, 8A has 8) directly indicates the number of valence electrons.

Answer:

A valence electron is an electron in the highest occupied energy level of an atom. The group number (1A - 8A) directly gives the number of valence electrons (e.g., Group 1A: 1 valence electron; Group 7A: 7 valence electrons; Group 8A: 8 valence electrons).