Which atom is bigger? Give a reason for each. (a) Be or Ba. (b) Mg or Cl. (c) B or F. (d) Rb or Li.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Which atom is bigger? Give a reason for each. (a) Be or Ba. (b) Mg or Cl. (c) B or F. (d) Rb or Li.
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. (a) Ba. It is far lower in group 2, with many more shells.
Step 2. (b) Mg. Both have three shells, but chlorine's larger nuclear charge pulls them in.
Step 3. (c) B. Both are in period 2, and fluorine has more protons.
Step 4. (d) Rb. It is lower in group 1, with more shells.
Answer: Ba, Mg, B and Rb.
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