Problem: Rubidium and bromine atoms are depicted below.Which pair best represents the relative ionic sizes?

FREE Expert Solution

Recall that ionic radius is the size of an ion. The trend for ionic radius is as follows: 

  • it increases from right to left and down a period in the periodic table. 
  • Ionic radius also increases with increasing number of electrons.


Rb+ and Br- have the same number of electrons which means they are isoelectronic

  • Rb → atomic # = 37 37 - 1 (lost e-): Rb36
  • Br→ atomic # = 35 35 + 1 (gained e-): Br-36


The ionic radius will just depend on the charge of the ion: the more positive the charge of an ion is, the smaller the ion is.

View Complete Written Solution
Problem Details

Rubidium and bromine atoms are depicted below.

Which pair best represents the relative ionic sizes?

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Periodic Trends: Ionic Radius concept. You can view video lessons to learn Periodic Trends: Ionic Radius. Or if you need more Periodic Trends: Ionic Radius practice, you can also practice Periodic Trends: Ionic Radius practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Van Dorn's class at ARIZONA.

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition. You can also practice Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition practice problems.