Comparing giant structures
Giant covalent structures
A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons. leads to the formation of A collection of two or more atoms held together by chemical bonds.. These can be:
- simple molecules, which contain a set number of atoms joined by covalent bonds
- giant A covalent substance is a molecule containing one or more covalent bonds (shared pairs of electrons). substances, which contain many atoms joined by covalent bonds
An example - silica
Silica is the main A substance formed by the chemical union of two or more elements. found in sand. It is an example of a giant covalent substance. It contains many silicon and oxygen atoms. These are joined together by covalent bonds in a regular arrangement, forming a A structure in which very large numbers of atoms are joined together by covalent bonds in a regular network..
Giant covalent substances are solids at room temperature and have very high The temperature at which a solid changes into a liquid as it is heated. and The temperature at which a substance rapidly changes from a liquid to a gas.. Covalent bonds are strong, so a lot of The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. is needed to break up these large structures during melting and boiling.
Giant covalent substances have no overall Property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative. For example, a negative charge causes a repulsive force on a neighbouring negative charge., so most cannot To allow electricity, heat or other energy forms to pass through. electricity. Graphite, a form of carbon which can conduct electricity, is an exception.
Giant ionic lattices
The structure of an An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron). is a giant ionic lattice.
Large numbers of oppositely charged Electrically charged particle, formed when an atom or molecule gains or loses electrons. are arranged in an alternating, regular three-dimensional structure. The electrostatic attraction between opposite charges is called an Ionic bonding forms between two atoms when an electron is transferred from one atom to the other, forming a positive-negative ion pair..
Ionic bonds are very strong so the melting point of an ionic compound is high.
Ionic compounds do not conduct electricity in the solid state because their ions are unable to move about. However, if an ionic compound is melted or dissolved, its ions become free to move about and it can conduct electricity.
Metallic structures
The structure of metals is based on a three-dimensional arrangement with layers of positive metal ions surrounded by a sea of negative Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.. The electrostatic attraction between the positive metal ions and the negative sea of electrons is called metallic bonding.
Metallic bonds are very strong so in general metals have high melting points and are strong and hard.
The layers of metal ions are able to slide across each other. This makes metals Capable of being hammered or pressed into a new shape without being likely to break or return to the original shape. and A ductile material is capable of being drawn into thin sheets or wires without breaking..
The electrons are free to move so metals are good conductors of electricity.