How many valence electron Arsenic have?

The modern periodic table is arranged into 7 horizontal rows (periods) and 18 vertical columns (groups).

Electrons in an atom are described by a set of four quantum numbers (n, l, m, s).

• The principal quantum number (n) indicates the main energy level or shell.
• Within each shell, electrons occupy subshells designated as s, p, d, and f.
• The specific arrangement of electrons in these subshells is called the electronic configuration.

The position of an element in the periodic table is determined by the quantum numbers of the last orbital filled. This directly links an element’s electronic configuration to its location in the table.

Example: Arsenic (As)

• Arsenic belongs to Group 15 of the periodic table.
• Hence, it has 5 valence electrons in its outermost shell.