Which atom in each of the following pairs has a larger radius?
a) Na or K
b) V or Zn
c) V or Ta
d) Li or Ba
a) The atomic radius generally increases as you move down a group in the periodic table. Sodium (Na) and Potassium (K) are both in Group 1, so the atomic radius of potassium is larger than that of sodium. Therefore, K has a larger radius than Na.
b) The atomic radius generally decreases as you move across a period in the periodic table. Vanadium (V) is located before zinc (Zn) in Period 4, so vanadium has a larger atomic radius than zinc. Therefore, V has a larger radius than Zn.
c) Similar to the previous case, the atomic radius generally decreases as you move across a period in the periodic table. Vanadium (V) is located before tantalum (Ta) in Period 5, so vanadium has a larger atomic radius than tantalum. Therefore, V has a larger radius than Ta.
d) Lithium (Li) is located before barium (Ba) in Group 2. As you move down a group, the atomic radius generally increases. Therefore, barium (Ba) has a larger atomic radius than lithium (Li). Hence, Ba has a larger radius than Li.
To determine which atom in each pair has a larger radius, we need to compare their atomic radii. Atomic radius refers to the size of an atom, usually measured in picometers (pm) or angstroms (Å).
a) Na or K:
To compare the atomic radii of sodium (Na) and potassium (K), we can look at their positions in the periodic table.
Both Na and K are located in the same period (the third period) of the periodic table, meaning they have the same number of electron shells. However, K has one extra electron shell compared to Na. As we move down a group, the atomic radius generally increases due to the addition of extra electron shells. Therefore, potassium (K) has a larger atomic radius compared to sodium (Na).
b) V or Zn:
Vanadium (V) and zinc (Zn) are located in different periods of the periodic table, so we cannot simply compare their positions to determine the atomic radius. However, we can consider the trend within a period. As we move from left to right across a period, the atomic radius generally decreases due to the increase in effective nuclear charge (the attractive force experienced by the valence electrons from the protons in the nucleus). Therefore, vanadium (V) has a larger atomic radius compared to zinc (Zn).
c) V or Ta:
Vanadium (V) and tantalum (Ta) are both transition metals, and they are located in the same period (the fifth period) of the periodic table. Since they have the same number of electron shells, we need to consider the effective nuclear charge. As we move from left to right across a period, the effective nuclear charge increases, leading to a decrease in atomic radius. Therefore, vanadium (V) has a larger atomic radius compared to tantalum (Ta).
d) Li or Ba:
Lithium (Li) and barium (Ba) are located in different periods of the periodic table. Similar to the previous comparison, we need to consider the trend within a period. As we move from left to right across a period, the atomic radius generally decreases. Hence, lithium (Li) has a larger atomic radius compared to barium (Ba).
In summary:
a) K has a larger radius than Na.
b) V has a larger radius than Zn.
c) V has a larger radius than Ta.
d) Li has a larger radius than Ba.