Which one of the following has the smallest radius?
The options are:
a) Na+
b) Cl-
c) Mg2+
d) Al3+
e) Be2+
The ion with the smallest radius is e) Be2+.
To determine which one of the following ions has the smallest radius, we need to consider the periodic trend of atomic radii.
As we move across a period from left to right on the periodic table, the atomic radius generally decreases. This is due to an increase in the number of protons in the nucleus, which attracts electrons more strongly and pulls the electron cloud closer to the nucleus.
Among the given options:
a) Na+: Sodium loses one electron to form the Na+ ion.
b) Cl-: Chlorine gains one electron to form the Cl- ion.
c) Mg2+: Magnesium loses two electrons to form the Mg2+ ion.
d) Al3+: Aluminum loses three electrons to form the Al3+ ion.
e) Be2+: Beryllium loses two electrons to form the Be2+ ion.
As we move from left to right across these options, the ions lose more electrons, resulting in a decreasing atomic radius.
Therefore, the ion with the smallest radius is:
b) Cl-: Chlorine gains one electron to form the Cl- ion.
Therefore, the correct answer is option b) Cl-.
To determine which one of the following ions has the smallest radius, we need to consider the periodic trends. In general, as we move across a period from left to right, the atomic radius decreases, and as we move down a group, the atomic radius increases.
Let's break down the options:
a) Na+: Sodium ion has a positive charge (Na+), which means it has lost an electron. Since it lost an electron, the ion has fewer electron-electron repulsions and therefore a smaller size compared to its neutral atom.
b) Cl-: Chloride ion has a negative charge (Cl-), which means it has gained an electron. The additional electron increases the electron-electron repulsions, causing the ion to expand in size compared to the neutral atom.
c) Mg2+: Magnesium ion has a 2+ charge (Mg2+), indicating that it has lost two electrons. Similar to sodium ion, magnesium ion also has a smaller size compared to its neutral atom due to the loss of electron-electron repulsions.
d) Al3+: Aluminum ion has a 3+ charge (Al3+), indicating that it has lost three electrons. Like sodium and magnesium ions, aluminum ions have a smaller radius compared to its neutral atom for the same reasons.
e) Be2+: Beryllium ion has a 2+ charge (Be2+), which means it has lost two electrons. Similar to the other cations, beryllium ion has a smaller size than its neutral atom due to the decrease in electron-electron repulsions.
Based on their charges and periodic trends, we can conclude that the ion with the smallest radius is:
a) Na+
because it has lost one electron and has the highest effective nuclear charge compared to the other ions provided.