Which is more reactive, and why? (a) Ca or Mg, as metals. (b) Rb or K. (c) Cl or Br, as non-metals.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Which is more reactive, and why? (a) Ca or Mg, as metals. (b) Rb or K. (c) Cl or Br, as non-metals.
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) Ca. It is below magnesium in group 2, so its outer electrons are lost more easily.
Step 2. (b) Rb. It is below potassium in group 1, with its outer electron farther out.
Step 3. (c) Cl. It is the smaller atom, so it pulls an extra electron in more strongly.
Answer: calcium, rubidium and chlorine.
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