Factors affecting the strength of metallic bonds include (d) The melting and boiling points of beryllium are higher than expected, because beryllium has a small atomic size and shows non-metallic behaviour, it forms strong Be-Be covalent bonds that lead to high melting and boiling points. Whereas Group 1 elements have 1 electron in the outermost shell and contribute one electron to form weak metallic bonds (c) The melting and boiling points of alkaline earth metals are higher than those of the alkali metals because they contribute 2 electrons to form a stronger metallic bond. (b) The melting point of magnesium is lower than expected probably because magnesium atoms are loosely packed in the metal crystal and experience low interatomic attractions. The strength of metallic bonds decreases down the group due to a decrease in nuclear attraction to the delocalized electrons as the electronegativity decrease. The melting points of group 2 generally decrease down the group due to the decrease in the strength of metallic bonds. The melting points generally decrease down the group as shown below Give one reason to explain why the elements of group II of the periodic table are strong reducing agents.Ī. Explain how the following factors vary within the group. The elements Be, Mg, Ca, Sr, Ba are in group II of the Periodic table. Both nuclear charge and screening effect increase but an increase in screening effect outweighs the increase in nuclear charge. Down the group, the number of electron shells and protons increases. Increase down the group due to a decrease in effective nuclear charge. The metallic property increases down the group.ĭecreases down the group because an increase in screening effect outweighs increases in nuclear attraction as the number of electron shells increase.Įlectronegativity is the relative tendency of an atom to attract bonding electrons. However, Group 2 elements are highly metallic that they form mainly ionic compound. Group 2 elements have higher ionization energy than group 1 elements, leading to less ionic compounds since less energy is required to form M + than M 2+. The ionization energy decreases down the group due to the decrease in the effective nuclear charge.ĭown the group both the nuclear charge and screening effect increase but increase in the screening outweighs the increase in nuclear charge.ī.
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