Study Chemistry notes on Group IV Elements for Secondary. Useful for revision, homework, and exam preparation in Zimbabwe.
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Group IV
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1
GROUP IV
General - occurs in the middle of the periodic table
- contains metals and non-metals
- metallic properties increase down group
- stability of +4 oxidation state decreases down group - the 'inert pair' effect
- all have the electronic configuration $\ldots n \mathbf{s}^{2} n \mathbf{p}^{2}$.
\begin{table}
\captionsetup{labelformat=empty}
\caption{ELEMENTS}
| C | Si | Ge | Sn | Pb
atomic number | 6 | 14 | 32 | &
electron config. | [He] $2 \mathrm{~s}^{2} 2 \mathrm{p}^{2}$ | [Ne] $3 \mathrm{~s}^{2} 3 \mathrm{p}^{2}$ | [Ar] $4 \mathrm{~s}^{2}{ }^{4} \mathrm{p}^{2}$ | $[\mathrm{Kr}] 5 \mathrm{~s}^{2} 5 \mathrm{p}^{2}$ | [Xe] 6s² $6 \mathrm{p}^{2}$
atomic radius / nm | 0.077 | 0.177 | 0.122 | 0.140 | 0.154
electronegativity | 2.5 | 1.8 | 1.8 | 1.8 | 1.8
1st I.E. / kj mol-1 | 1086 | 786 | 760 | 710 | 720
description | non-metal | metalloid | metalloid | metal | metal
bonding | gaint covalent | giant covalent | giant covalent | metallic | metallic
melting point / ${ }^{\circ} \mathrm{C}$ | 3550 (diam) | 1410 | 940 | 232 | 328
boiling point $/\left({ }^{\circ} \mathrm{C}\right.$ | 4830 (diam) | 2680 | 2830 | 2690 | 1751
electrical conductivity | graphite - good diamond - poor | semiconductor | semiconductor | good | good
\end{table}
TRENDS
Melting Point | General decrease down group | & C | Si | Ge | Sn | Pb
| Melting point $/{ }^{\circ} \mathrm{C}$ | & 3550 | 1410 | 940 | 232 | 328
\multicolumn{8}{|c|}{
- change from giant molecular to metallic bonding
- many bonds need to be broken to separate the atoms in giant molecules
- the larger the atoms the weaker the covalent bond
}
\multirow[t]{5}{*}{Electrical conductivity} | \multicolumn{7}{|c|}{
C diamond
poor graphite good
}
| Si | & semiconductor | \multicolumn{4}{|l|}{\multirow[b]{4}{*}{
metallic bonding - delocalised electron cloud
metallic bonding - delocalised electron cloud
}}
| Ge | & semiconductor | & | &
| Sn | good | & | & |
| Pb | good | & | & |