COVALENT BONDING Flashcards
Covalent bonding involves bonding between what substances?
The bonding that takes place between 2 Non-Metals.
Example O2
What is a definition of covalent bonding?
A shared pair of electrons between the nuclei of two atoms.
NOTE: Non metals need to gain electrons to complete the other shell so they share electrons.
How do you know how many covalent bonds will be formed?
The number of bonds to be formed will be the number required to complete the outer shell.
EXAMPLE:O2 Oxygen is short of two electrons so it will form a double covalent bond.
What are the two types of structures formed during covalent bonding?
- Giant covalent Lattice
- Simple Covalent molecules.
What is a giant covalent lattice?
Massive compounds where all the atoms are bonded together by very strong covalent bonds.
Give two examples of compounds which have covalent lattices?
Diamond and Graphite
What are the characteristics of diamond which is a form of carbon?
A. It has 4 electrons in its outer shell so forms 4 covalent bonds in a tetrahedral arrangement.
B. High melting and boiling point.
C. Very hard and used in industrial drilling.
D.Does NOT conduct electricity because it contains no free electrons or ions.
Is carbon a metal?
No
What are the 4 characteristics of graphite which is also a form of carbon?
A. Graphite is arranged like a pack of cards with strong bonds in each layer but weak intermolecular forces between each layer.
B High melting and boiling point. You need a lot of energy to break the strong covalent bonds.
C. Very soft.
D. Conducts electricity because the fourth outershell electron is free to move and becomes “delocalised” allowing it to conduct electricity.
Explain why graphite conducts electricity?
it has delocalised electrons which allow movement.
Diamond and graphite are both forms of ALLOTROPES.
What does this mean?
They are different forms of the same element which is carbon.
What are simple covalent molecules?
Separate molecules with weak intermolecular forces between them.
Example : H2- Hydrogen 02 Oxygen.
NOTE: Most questions for GCSE are on simple molecules.
Do simple molecules need a lot of energy to break them down?
No as they have low melting and boiling points.
What happens when simple molecules are melted or boiled?
The attraction between the molecules is broken NOT the covalent bond within the molecule.
What effect does a higher molecular mass have on boiling or melting points?
The higher the mass the higher the melting and boiling points because more energy is needed to break the weak intermolecular forces between molecules.
NOTE: In exam questions on molecular mass don’t forget to use the periodic table to work out the mass. If you have CL2 you need X the mass by 2.
