# What is the electron configuration for arsenic (As)?

Well, what is ${Z}_{\text{atomic number}}$ for arsenic?
A quick glance at the Table (what table?, the kitchen table) tells us that $Z = 33$... And if there are 33 positively-charged nuclear particles, the NEUTRAL atom must contain 33 NEGATIVELY-charged extra-nuclear particles, i.e. 33 electrons arranged according to the $\text{aufbau scheme}$:
$A s : {\underbrace{1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{10} 4 {s}^{2} 4 {p}^{3}}}_{\text{33 electrons as required...}}$