Question

what is the noble gas configuration for beryllium? 5/10 li2s1 he2s2 li2s2 he1s2

Explanation:

Step1: Recall beryllium's atomic number

Beryllium has atomic number 4.

Step2: Recall noble - gas configuration concept

Noble - gas configuration uses the closest previous noble gas to start the electron - configuration shorthand.

Step3: Identify closest noble gas to beryllium

The closest noble gas to beryllium with a lower atomic number is helium (He), which has 2 electrons.

Step4: Write beryllium's noble - gas configuration

Beryllium has 4 electrons. After accounting for the 2 electrons of helium, the remaining 2 electrons go into the 2s orbital. So the noble - gas configuration is [He]2s².

Answer:

[He]2s²