Answer to Question #204759 in General Chemistry for jay

Question

Differentiate between the following types of bonds, using an illustration in each case to assist in your answer. i. Metallic bonding ii. Hydrogen bonding iii. Ionic bonding (6 marks) B. i. State THREE (3) properties of covalent compounds. (3 marks) ii. Draw the Lewis structure for the molecule of ammonia (NH3). (2 marks) iii. State the geometry of, and the bond angles in, the ammonia (NH3) molecule. (2 marks) iv. PH3 has the same geometry as NH3, however, the bond angle in PH3 is less than that in NH3. Provide an explanation for this observation. (3 marks) C. i. Define the term ‘electronegativity.’ (2 marks) ii. Explain how the concept of electronegativity relates to bond polarity. (2 marks)

Answer 1

Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions.

Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

Ionic bond, also called electrovalent bond, type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound. ... Such a bond forms when the valence (outermost) electrons of one atom are transferred permanently to another atom.

Properties of Covalent Molecular Compounds.

• Low melting points and boiling points. A relatively small amount of energy is required to overcome the weak attractions between covalent molecules, so these compounds melt and boil at much lower temperatures than metallic and ionic compounds do. In fact, many compounds in this class are liquids or gases at room temperature.
• Low enthalpies of fusion and vaporization These properties are usually one or two orders of magnitude smaller than they are for ionic compounds.
• Soft or brittle solid forms. The weak intermolecular forces makes the solid form of covalent molecular compounds easy to distort or break.
• Poor electrical and thermal conductivity. Ionic compounds conduct electricty well when melted; metallic solids do as well. Covalent molecular compounds do not.

The Lewis structure of ammonia, NH3