In this section we’re going to take a look at the different properties of different elements and how this impacts their abilities.
Let’s first draw some comparisons between different elements.
Compounds and elements, whilst they are similar, are different due to it being difficult to separate the elements within a compound.
A compound contains at least two elements which are chemically combined. It is more difficult to separate elements once they are in a compound because a chemical reaction has taken place and there has been a transfer or sharing of electrons between the atoms.
Both ions and noble gasses, whilst different, both share the same electronic structure. When a metal and a non-metal react, the atoms involved gain or lose electrons to form charged ions. The ions have a stable electronic structure, the same as a noble gas.
For example, when magnesium (2,8,2) loses two electrons to become an ion with a 2+ charge, it is left with the stable electronic structure of neon (2,8).
Now what about structures and electric conductivity?
Ionic compounds, dissolved ionic compounds, metals and graphite are all able to conduct electricity because they have charged particles.
Molten and dissolved ionic substances contain charged ions which are free to move around and carry a charge. In metals, the ions are held together in a regular structure and so can’t move around to carry a charge, but delocalised electrons move freely throughout the structure so metals can also conduct electricity.
Graphite is the only giant covalent substance which can conduct electricity. This is because delocalised electrons are free to move between carbon atoms and so can carry a charge.
On the other hand ethanol would not conduct electricity as it has a simple covalent structure.
Many simple molecules exist as liquids or gases at room temperature because they have low melting and boiling points. Simple molecules can also be solids with low melting points. Simple covalent molecules cannot conduct electricity as they do not carry a charge.
Solid potassium iodide, which is an ionic compound, cannot conduct electricity, because although the ions are charged they are not free to move around when they are in the solid. However, in molten potassium iodide, the ions are free to move around and so can conduct electricity.