Non-metallic character increases across a period from left to right as the effective nuclear charge increases and the ability to gain electrons improves. Lithium (Group 1) is the most metallic, while Fluorine (Group 17) is the most non-metallic among the listed elements.
3532
In the modern periodic table, elements within the same group share which common characteristic?
Elements in the same group of the periodic table possess the same number of valence electrons in their outermost shell. This similarity in electronic configuration is the primary reason why elements in the same group exhibit similar chemical properties.
3533
Why does lithium exhibit chemical properties similar to magnesium despite being in different groups?
This phenomenon is known as the diagonal relationship. Lithium (Group 1, Period 2) and Magnesium (Group 2, Period 3) have similar ionic charge-to-size ratios (ionic potential), which leads to similar polarizing power and chemical behavior, such as the solubility of their compounds.
3534
Which of the following elements was discovered later and successfully filled a gap in Mendeleev's periodic table?
Dmitri Mendeleev famously left gaps in his periodic table for elements that had not yet been discovered. Germanium (Ge), which he predicted as 'eka-silicon', was later discovered and fit perfectly into the predicted position, confirming the predictive power of his periodic law.
3535
Which element was predicted by Mendeleev as 'eka-aluminium' before its discovery?
Dmitri Mendeleev predicted the existence and properties of an element he called 'eka-aluminium' to fill a gap in his periodic table. This element was later discovered and named Gallium, which matched his predictions remarkably well.
3536
How were elements organized in Mendeleev's original periodic table?
Dmitri Mendeleev formulated his periodic law based on the observation that the properties of elements are a periodic function of their atomic masses. He arranged elements in rows and columns in increasing order of their atomic weights to highlight periodic trends.
3537
How does the chemical reactivity of non-metals change as you move down a group in the periodic table?
Non-metals react by gaining electrons. As you move down a group, the atomic size increases and the valence shell becomes further from the nucleus. This increases shielding and decreases the effective nuclear attraction for incoming electrons, making it harder for the atom to gain electrons and thus decreasing its non-metallic reactivity.
3538
Match the following terms in List I with their corresponding definitions or descriptors in List II.
Modern Periodic Law was proposed by Moseley (a-2). Mendeleev is known as the Father of the Periodic Table (b-4). Groups are the vertical columns in the periodic table (c-1). Periods are the horizontal rows in the periodic table (d-3). Thus, the correct matching is a-2, b-4, c-1, d-3.
3539
How many electron shells are present in the atoms of elements belonging to the third period?
In the periodic table, the period number corresponds directly to the principal quantum number of the outermost shell being filled. Therefore, all elements in the third period have their valence electrons in the third shell (n=3), meaning they possess exactly three electron shells.
3540
Which of the following pairs of atomic numbers represents elements that belong to the same group in the periodic table?
Elements in the same group have the same number of valence electrons. Atomic number 13 is Aluminum (Group 13) and atomic number 31 is Gallium (Group 13). Both share the same valence electron configuration (ns2 np1), placing them in the same group.
