As you move from left to right across a period, the number of protons in the nucleus increases, which increases the effective nuclear charge. Since the electrons are being added to the same valence shell, the increased nuclear attraction pulls the electron cloud closer to the nucleus. Consequently, the atomic radius decreases across the period from sodium to chlorine.
3752
What factor primarily causes the atomic radius to increase as one moves down a group in the periodic table?
As you move down a group in the periodic table, each subsequent element has an additional principal energy level or electron shell. This increase in the number of shells increases the distance between the nucleus and the outermost electrons, thereby increasing the atomic radius despite the increase in nuclear charge.
3753
The modern long-form periodic table is organized based on which fundamental property of elements?
The modern periodic table is based on the Periodic Law, which states that the physical and chemical properties of elements are periodic functions of their atomic numbers. Atomic number represents the number of protons in the nucleus, which determines the electronic configuration and chemical behavior of the element.
3754
What atomic property of carbon contributes to its ability to form exceptionally strong bonds?
Carbon has a small atomic radius, which allows the nucleus to exert a strong attraction on shared bonding electrons. This proximity leads to shorter, stronger covalent bonds compared to larger atoms in the same group. The small size also facilitates effective orbital overlap, which is essential for the stability of the carbon-carbon bonds found in organic molecules.
3755
On what basis did Mendeleev organize the periodic nature of element properties in his periodic table?
Mendeleev's Periodic Law stated that the properties of elements are a periodic function of their atomic masses. He arranged elements in order of increasing atomic mass, which allowed him to predict the existence and properties of elements that had not yet been discovered at that time.
3756
Which of the following halogen atoms possesses the largest atomic diameter?
Atomic radius increases down a group in the periodic table due to the addition of successive electron shells. Among the halogens (Group 17), iodine is located furthest down the group, resulting in the largest atomic radius and diameter compared to fluorine, chlorine, and bromine.
3757
Which of the following sets of elements constitutes a valid Dobereiner triad?
Johann Wolfgang Dobereiner identified groups of three elements, known as triads, where the atomic mass of the middle element is approximately the average of the other two. The triad of Lithium (Li), Sodium (Na), and Potassium (K) is a classic example, where the atomic mass of sodium is roughly the mean of the atomic masses of lithium and potassium.
3758
How does the atomic size change when an electron is removed to form a cation versus when an electron is added to form an anion?
Removing an electron reduces electron-electron repulsion and increases the effective nuclear charge per electron, causing the radius to decrease (cation formation). Adding an electron increases electron-electron repulsion and shields the outer electrons more effectively, leading to an increase in the ionic radius (anion formation).
3759
How are elements arranged in the modern periodic table?
The modern periodic table arranges elements in increasing order of their atomic numbers (the number of protons). This arrangement corrects the anomalies found in Mendeleev's table, which was based on atomic mass, and aligns elements with similar electronic configurations in the same groups.
3760
Among the following elements, which one has the largest atomic radius?
In a period, atomic radius decreases from left to right due to increasing effective nuclear charge. Aluminum (Al), Silicon (Si), Phosphorus (P), and Sulfur (S) are all in the third period. Since Al is the leftmost element among these, it has the largest atomic size.
