As Chemistry Notes
Topic 5 – Bonding and Structure
Revision Notes
1) Introduction
• Atoms form bonds to get a full outer shell of electrons • There are three types of bonding: ionic, covalent and metallic • The structures produced by forming bonds are either giant or simple • The possible combinations of structure and bonding are giant ionic, simple covalent, giant covalent and giant metallic • Simple covalent is sometimes called simple molecular • Giant covalent is sometimes called giant molecular or macromolecular • To melt a substance the forces holding the particles together need to be broken • To conduct electricity there must something charged that can move (ions or electrons). Technically this is called a mobile charged species • To dissolve in a particular solvent the substance must interact with the solvent
2) Types of Bonding
▪ Ionic bonding – metals transfer electrons to non-metals producing positive metal ions and negative non-metal ions. An ionic bond is an electrostatic attraction between oppositely charged ions. Dot-cross diagrams show outer electrons only e.g. NaCl
[pic][pic]
▪ Covalent bonding – A covalent bond is a shared pair of electrons. Only non-metals can get a full shell by sharing electrons. The bond is the attraction of the shared electrons for the two nuclei. Dot-cross diagrams show outer electrons only e.g. Cl2
[pic]
▪ In dative covalent bonds, one atom provides both of the shared pair of electrons e.g. formation of an ammonium ion, NH4+, from ammonia, NH3, and H+
[pic] ▪ Metallic bonding – metals lose their outer shell electrons to produce a lattice of positive metal ions surrounded by delocalised (free) electrons.
[pic]
3) Types of Structure
a) Giant ionic lattices e.g. sodium chloride
o Lattice of oppositely charged ions. o High melting and boiling points (strong forces of attraction between ions need to be broken). o Do not conduct when
Revision Notes
1) Introduction
• Atoms form bonds to get a full outer shell of electrons • There are three types of bonding: ionic, covalent and metallic • The structures produced by forming bonds are either giant or simple • The possible combinations of structure and bonding are giant ionic, simple covalent, giant covalent and giant metallic • Simple covalent is sometimes called simple molecular • Giant covalent is sometimes called giant molecular or macromolecular • To melt a substance the forces holding the particles together need to be broken • To conduct electricity there must something charged that can move (ions or electrons). Technically this is called a mobile charged species • To dissolve in a particular solvent the substance must interact with the solvent
2) Types of Bonding
▪ Ionic bonding – metals transfer electrons to non-metals producing positive metal ions and negative non-metal ions. An ionic bond is an electrostatic attraction between oppositely charged ions. Dot-cross diagrams show outer electrons only e.g. NaCl
[pic][pic]
▪ Covalent bonding – A covalent bond is a shared pair of electrons. Only non-metals can get a full shell by sharing electrons. The bond is the attraction of the shared electrons for the two nuclei. Dot-cross diagrams show outer electrons only e.g. Cl2
[pic]
▪ In dative covalent bonds, one atom provides both of the shared pair of electrons e.g. formation of an ammonium ion, NH4+, from ammonia, NH3, and H+
[pic] ▪ Metallic bonding – metals lose their outer shell electrons to produce a lattice of positive metal ions surrounded by delocalised (free) electrons.
[pic]
3) Types of Structure
a) Giant ionic lattices e.g. sodium chloride
o Lattice of oppositely charged ions. o High melting and boiling points (strong forces of attraction between ions need to be broken). o Do not conduct when