Which atom is larger, lithium (Li) or beryllium (Be)? Explain your answer.

To determine which atom is larger, we need to compare the atomic radii of lithium (Li) and beryllium (Be). These values can be found in a periodic table or a table of atomic radii. For this problem, we will use the following values: - Atomic radius of Li: \(152 \,pm\) - Atomic radius of Be: \(111 \,pm\)

Now we can compare the atomic radii to identify which atom is larger. Since the atomic radius of Li (\(152 \,pm\)) is greater than the atomic radius of Be (\(111 \,pm\)), we can conclude that lithium atom is larger than beryllium atom.

To explain why lithium is larger than beryllium, we need to consider their electron configurations, electron shielding, and effective nuclear charge. Lithium (Li) has an atomic number of 3, which means it has 3 protons in its nucleus and 3 electrons in its electron cloud. Its electron configuration is \(1s^2 2s^1\). Beryllium (Be) has an atomic number of 4, so it has 4 protons in its nucleus and 4 electrons in its electron cloud. Its electron configuration is \(1s^2 2s^2\). Both Li and Be have 2 electrons in the inner \(1s\) orbital. However, Li has only 1 electron in the \(2s\) orbital, while Be has 2 electrons in the same orbital. This means that the effective nuclear charge (the net positive charge experienced by an electron) is greater for Be than for Li, leading to a stronger attraction of the electrons in Be towards its nucleus, which causes its atomic size to decrease. Additionally, electron shielding plays a role in atomic size differences. In this case, the effect of electron shielding is similar for both elements as they have the same electron configuration in the \(1s\) orbital. However, the higher effective nuclear charge in Be causes its electrons to be drawn closer to the nucleus, making it smaller than Li. Hence, considering all these factors, we can conclude that lithium (Li) is larger than beryllium (Be).