The atomic radius of magnesium is 160 pm and of sulphur 103 pm.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The atomic radius of magnesium is and of sulphur . By what percentage of magnesium's radius is the sulphur atom smaller? Why is it smaller?
Need a reminder? The key ideaShow
Across a period atoms get smaller, because more protons pull the same shells in. Down a group they get bigger, because a shell is added. Metallic character, the tendency to lose electrons, falls across a period and rises down a group.
The worked solution
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. Drop. .
Step 2. Percentage. .
Step 3. Reason. Both atoms have three shells, but sulphur has protons against magnesium's . The stronger pull draws the shells in.
Answer: smaller, because of the larger nuclear charge.
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