Which of the following groups has the species listed correctly in order of increasing radius?
1. Mg +2, Ca +2, Ba +2
2. Fe, Fe +2, Fe +3
3. Na, Mg, Al
4. Br-, Cl-, F-
5. K+, Na+, Li+
Is it 1. Mg +2, Ca +2, Ba +2 ?
yes
To determine which of the following groups has the species listed correctly in order of increasing radius, we need to consider the periodic trends related to atomic radius.
Atomic radius generally decreases across a period (from left to right) and increases down a group in the periodic table.
Let's analyze each group:
1. Mg +2, Ca +2, Ba +2: This group consists of alkaline earth metals (Group 2). As we move down the group, the atomic radius increases. Therefore, the order is correct.
2. Fe, Fe +2, Fe +3: This group consists of iron (Fe) and its ions. As we move from neutral Fe to positively charged ions, the atomic radius generally decreases because of the increasing nuclear charge pulling the electrons closer. Therefore, the order is not correct.
3. Na, Mg, Al: This group consists of alkali metals (Group 1) and an alkaline earth metal (Group 2). As we move down the alkali metals, the atomic radius increases. But when we move from Mg (alkaline earth metal) to Al (Group 13), the atomic radius decreases slightly. Therefore, the order is not correct.
4. Br-, Cl-, F-: This group consists of halogens (Group 17) and their negative ions. As we move up the group, the atomic radius generally decreases due to an increased effective nuclear charge. Therefore, the order is not correct.
5. K+, Na+, Li+: This group consists of alkali metals (Group 1) and their positive ions. As we move down the group, the atomic radius increases. Therefore, the order is correct.
So, the group with the species listed correctly in order of increasing radius is 1. Mg +2, Ca +2, Ba +2.