Structure and bonding in the first 20 elements

Pregunta	Respuesta
Do metallic elements have high or low boiling points?	High boiling points as there is a strong attraction between the metal ions and delocalised electrons
Name some covalent molecular elements.	All diatomic elements (e.g. nitrogen, oxygen) Phosphorus Sulphur Fullerenes (carbon)
What are the intermolecular forces between covalent molecular elements?	London dispersion forces
Name some covalent network elements.	Diamond (carbon) Carbon (graphite) Boron Silicon
Why do covalent networks have very high melting points?	Many strong covalent bonds must be broken
Why is carbon in the form of graphite an effective lubricant?	Graphite is formed in layers which are held together by weak LDF's. The layers can easily move.
Why can carbon in the form of graphite conduct?	Each carbon forms 3 covalent bonds, the fourth outer electrom becomes delocalised.
What are monatomic elements?	Single atoms which are not bonded to neighbouring atoms.
Name some monatomic elements.	All of the noble gases (e.g. helium, neon)
Why do noble gases have very low melting points?	They are held together by weak LDF's which are easily broken.
Why does sodium have a higher melting point than chlorine?	To melt sodium strong metallic bonds must be broken, this requires lot's of energy. On the other hand, chlorine molecules are held together by weak London dispersion forces, so they can be easily separated.

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	Creado por Lana Duncan hace más de 9 años