Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Arsenic has . Write its configuration with a noble gas core, and find its period, group and block.
The period is the principal quantum number of the outermost shell. s-block: groups 1 and 2, . p-block: groups 13 to 18, group + outer s and p electrons. d-block: groups 3 to 12, group = d electrons + outer s electrons. f-block: lanthanoids (4f, period 6) and actinoids (5f, period 7).
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Configuration. electrons after argon: .
Step 2. Period. The outermost shell is : period 4.
Step 3. Block and group. The last electron enters : p-block. Group .
Answer: period 4, group 15, p-block.
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