2.1 INVESTIGATING STRUCTURE & BONDING
29 December 2020
12:35
There are 2 main types of structures:
● Giant structures
● Simple molecular structures
Materials with giant structures form crystals.
● All atoms or ions are linked by a network of strong bonding throughout the
lattice structure.
This strong bonding results in higher m.p/b.p.
Mainly ionic solids, giant covalent solids and metals.
Substances with simple molecular structures consist of small groups of atoms.
● They are linked by covalent bonds between the atoms, which are strong, but
the intermolecular forces are weak.
These weak intermolecular, weak forces between the molecules, allow the molecules
to be separated easily.
● Low m.p/b.p.
, 2.2 IONIC BONDING & STRUCTURES
29 December 2020
14:01
Ionic bond - Strong electrostatic force of attraction between oppositely charged ions.
Occurs between elements whose atoms need to lose electrons and those which need
to gain electrons to gain the nearest noble gas electron configuration.
● Electrons are transferred from one atom to the other.
The atoms which lose electrons become positively charged ions.
● Cations.
The atoms which gain electrons become negatively charged ions.
● Anions.
When metals and non-metals react, the ions produced form ionic crystals.
● A giant lattice structure, a regular 3D arrangement of atoms or ions.
Bonds are in all directions of the lattice structure.
Forces of repulsion in the ionic lattice:
● The ions of the same charges repel.
● The nuclei of the ions repel.
The greater the charge on an ion, the stronger the ionic bond.
Smaller ionic radii, the stronger the ionic bond, as they can be closely packed
together.
As you go down a group, atomic and ionic radii increases, as the atomic number
increases.
● Extra electron shells are added.
The positive ion of an element (metal) is smaller than its atomic radius as it loses the
electrons from the outer shell.
● Electrons in the ion are held more tightly.
The negative ion of an element (non-metal) is larger than its atomic radius as it gains
electrons in its outer shell.
29 December 2020
12:35
There are 2 main types of structures:
● Giant structures
● Simple molecular structures
Materials with giant structures form crystals.
● All atoms or ions are linked by a network of strong bonding throughout the
lattice structure.
This strong bonding results in higher m.p/b.p.
Mainly ionic solids, giant covalent solids and metals.
Substances with simple molecular structures consist of small groups of atoms.
● They are linked by covalent bonds between the atoms, which are strong, but
the intermolecular forces are weak.
These weak intermolecular, weak forces between the molecules, allow the molecules
to be separated easily.
● Low m.p/b.p.
, 2.2 IONIC BONDING & STRUCTURES
29 December 2020
14:01
Ionic bond - Strong electrostatic force of attraction between oppositely charged ions.
Occurs between elements whose atoms need to lose electrons and those which need
to gain electrons to gain the nearest noble gas electron configuration.
● Electrons are transferred from one atom to the other.
The atoms which lose electrons become positively charged ions.
● Cations.
The atoms which gain electrons become negatively charged ions.
● Anions.
When metals and non-metals react, the ions produced form ionic crystals.
● A giant lattice structure, a regular 3D arrangement of atoms or ions.
Bonds are in all directions of the lattice structure.
Forces of repulsion in the ionic lattice:
● The ions of the same charges repel.
● The nuclei of the ions repel.
The greater the charge on an ion, the stronger the ionic bond.
Smaller ionic radii, the stronger the ionic bond, as they can be closely packed
together.
As you go down a group, atomic and ionic radii increases, as the atomic number
increases.
● Extra electron shells are added.
The positive ion of an element (metal) is smaller than its atomic radius as it loses the
electrons from the outer shell.
● Electrons in the ion are held more tightly.
The negative ion of an element (non-metal) is larger than its atomic radius as it gains
electrons in its outer shell.
