Bonding and structure explorer
Heat, strike and test the conductivity of giant ionic, giant covalent, metallic and simple molecular substances, and explain what you see from their particles.
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Learning objectives
- relate the physical properties (including electrical property) of ionic compounds to their lattice structure.
- relate the physical properties (including electrical property) of covalent substances to their structure and bonding.
- describe the general physical properties of metals as solids having high melting and boiling points, malleable and good conductors of heat and electricity
- state that ionic materials contain a giant lattice in which the ions are held by electrostatic attraction, e.g. NaCl (candidates will not be required to draw diagrams of ionic lattices)
- relate the physical properties (including electrical property) of ionic compounds to their lattice structure (see also 3.4(g)).
- relate the physical properties (including electrical property) of covalent substances to their structure and bonding (see also 3.4(g)).
- describe metals as a lattice of positive ions in a ‘sea of electrons’
- describe the general physical properties of metals as solids having high melting and boiling points, malleable, good conductors of heat and electricity in terms of their structure (see also 3.4(g)).
- compare the structures of the following substances in order to deduce their properties: — simple molecular substances, e.g. methane, iodine
- compare the structures of the following substances in order to deduce their properties: — giant covalent substances, e.g. sand (silicon dioxide), diamond, graphite (see also 3.4(g))
- compare the bonding and structures of diamond and graphite in order to deduce their properties such as electrical conductivity, lubricating or cutting action (candidates will not be required to draw the structures)
- deduce the physical and chemical properties of substances from their structures and bonding and vice versa (see also 3.1(d), 3.2(d), 3.3(b) and 3.4(e)).
- describe, in simple terms, the lattice structure of a crystalline solid which is: — ionic, as in sodium chloride and magnesium oxide
- describe, in simple terms, the lattice structure of a crystalline solid which is: — simple molecular, as in iodine
- describe, in simple terms, the lattice structure of a crystalline solid which is: — giant molecular, as in graphite and diamond
- describe, in simple terms, the lattice structure of a crystalline solid which is: — hydrogen-bonded, as in ice
- describe, in simple terms, the lattice structure of a crystalline solid which is: — metallic, as in copper [the concept of the ‘unit cell’ is not required]
- describe, interpret and/or predict the effect of different types of structure and bonding on the physical properties of substances
- Solids: Structure and Physical Properties
Sodium chloride, a giant ionic structure, at 25 °C: a solid. The circuit is off.
- State
- solid
- Melting point
- —
- Boiling point
- —
- Bulb
- switched off
- Melting overcomes
- —
Try this
0 of 4 doneMelt a giant structure and a simple molecular substance. (not done yet)
Melting a giant structure breaks strong bonds all through it; melting a simple molecular substance only overcomes weak forces between molecules, which takes far less energy.
Test sodium chloride as a solid, as a melt and in water. (not done yet)
Ions carry the current, but only when they can move: in the melt or the solution, not when held in the lattice.
Strike sodium chloride, then copper. (not done yet)
A blow pushes ions of the same charge next to each other in NaCl, so they repel and the crystal shatters. In copper the layers of ions slide in the sea of electrons, so the metal bends instead.
Test diamond and graphite for conductivity. (not done yet)
Each carbon in graphite bonds to three others, leaving one electron per atom delocalised along its layer. Diamond uses all four outer electrons in bonds, so nothing can carry a current.