? asked in 科學及數學化學 · 1 decade ago

chemistry about Metallic bond

The smaller size of metal atom,the stronger metallic bond.

The higher no. of outermost electrons involved in metallic bond,the

stronger metallic bond.

咁我想問下,好似Na,Mg,Al呢3個elements,在同一個period,我可以知道 Al's metallic bond > Mg's metallic bond > Na's metallic bond

但以上情況係同一個period先比較到,如果我想比較Na同Be

佢地唔係在同一個period,又不是在同一個group,

Na's atom size大過Be,但同時,Be's outermost electrons又多過Na

咁我點比較佢地2個elements,邊一個metallic bond較強?

1 Answer

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  • 1 decade ago
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    In comparison of the strength of metallic bonds, metals in the same group or in the same period are usually used.

    In the comparison of the strength of two metals belong to neither the same group nor the same period, both the factor of number of the outermost shell electrons per atom and that of the atomic size must be considered.

    Case 1: The two effects are parallel

    For example: To compare the strength of metallic bonds of Na and Be

    When considering only the factor of number of outermost shell electrons per atom, Be has stronger metallic bonds than Na, because Be has more outermost shell electrons.

    When considering only the factor of atomic size, Be has stronger metallic bonds than Na, because Be has a smaller size.

    Therefore, Be has stronger metallic bonds than Na.

    Case 2: The two effects are opposite

    For example: To compare the strength of metallic bonds of Na and Ca

    When considering only the factor of number of outermost shell electrons per atom, Ca has stronger metallic bonds than Na, because Ca has more outermost shell electrons.

    When considering only the factor of atomic size, Na has stronger metallic bonds than Ca, because Na has a smaller size.

    The two effects are opposite. For this example, the effect of number of outermost shell electrons per atom outweighs the effect of atomic size. Therefore, Ca has stronger metallic bonds than Na.

    In most cases (not for all cases), the effect of number of outermost shell electrons per atom outweighs the effect of atomic size.

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