Bonding Flashcards
Explain the properties of metals.
Electrical conductivity - When a metal is connected at both ends to the negative and positive terminals of an electrical circuit, the mobile valence electrons will move towards the positive end.
Heat conductivity - If one end of the metal is dipped into something hot it’s electrons absorb heat energy and they move at a greater speed. These electrons collide with other electrons and their energy is transferred. The heat energy will transported to the other end of the metal very rapidly.
Malleability and ductility - When a layer of cations is sheared, the mobile valence electrons adjust to the new arrangement, allowing the layer of cations to slide over another without disrupting the metallic bonding.
Explain the properties of covalent network substances.
Very high melting points - The covalent bonds that hold the atoms together are strong and require a lot of energy to break these bonds.
Cannot conduct electricity in solid and liquid States - There are no charged particles that are free to move throughout the structure.
Insoluble in water and most other solvents - There is no attraction between the atoms in the network (no charge) and water molecules.
Define and describe covalent bonds.
A covalent bond is a sharing of electrons. It consists of a pair of electrons between two positive nuclei. The nuclei repel each other, but are attracted by the pair of negatively charged elections. It involves a balance between this attraction and repulsion and requires a lot of energy to overcome these forces.
Define and describe ionic bonds.
Ionic bonds are bonds which involve the electrostatic attraction between metal atoms that have lost electrons and non-metal atoms that have gained electrons.
Define and describe metallic bonds.
Metallic bonds are formed by the electrostatic attraction between the positive nuclei of metal atoms and shared delocalised electrons.
Explain the properties of covalent molecular substances.
Low melting and boiling points - The forces that hold the molecules together in the solid and liquid state are weak.
Cannot conduct electricity in solid and liquid states - There are no charged particles that can move through the substance.
Tend to be malleable - The forces between molecules are weak, so molecules are easily moved relative to each other.
Variable solubility - Solubility depends on the intermolecular forces which vary between substances.
What determines the ability of atoms to form chemical bonds?
The arrangement of electrons within an atom and the stability of the valence electron shell.
Define and describe the allotropes of carbon.
Elemental carbon exists as a range of different forms (allotropes) including graphite, diamond and fullerenes, each with significantly different structures and physical properties. Graphite and diamond are examples of covalent network substances.
What is a covalent molecular substance?
A covalent molecular substance is made of discrete molecules in which the atoms are held together by covalent bonding. In a solid or liquid, there are weak intermolecular forces holding the molecules together. These weak forces are responsible for the typical physical properties.
What is a covalent network substance?
Substances that are made up of three-dimensional networks of covalently bonded atoms. The three-dimensional nature of the network means the atoms are held rigidly in position by very strong bonds.
What is petrol - list some advantages and disadvantages?
A mixture of organic liquids (crude oil and natural gas). It occurs naturally in the ground and was formed millions of years ago. Crude oil contains mixtures of hydrocarbon compounds and a small quantity of other materials such as water, oxygen, nitrogen and sulphur.
What is bioethanol - list some advantages and disadvantages?
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What is biodiesel - list some advantages and disadvantages?
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What is diesel - list some advantages and disadvantages?
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