C2- Bonding Flashcards
What is ionic bonding?
The electrostatic attraction between positive and negative ions. It is a relatively strong attraction.
How are ionic compounds held together?
They are held together in a giant lattice.
What is a giant lattice?
It’s a regular structure that extends in all directions in a substance.
What holds the structure of ionic compounds together?
Electrostatic attraction between positive and negative ions holds the structure together.
What are the melting and boiling points of ionic substances?
Ionic substances have high melting and boiling points due to strong electrostatic forces between oppositely charged ions.
Do ionic substances conduct electricity when solid?
No, ionic substances do not conduct electricity when solid because the ions are in fixed positions.
When do ionic substances conduct electricity?
Ionic substances conduct electricity when molten or dissolved in water, as the ions are free to move.
What is a covalent bond?
Covalent bond is a shared pair of electrons between two atoms.
Non-metal - non-metal bond
What is a characteristic of simple molecular covalent substances regarding electricity?
They do not conduct electricity because there are no ions.
How large are molecules in a simple molecular covalent substance?
They consist of small molecules.
What type of forces exist between simple molecular covalent substances?
They have weak intermolecular forces.
What are the melting and boiling points of simple molecular covalent substances?
They have low melting and boiling points.
How do intermolecular forces change as the mass/size of the molecule increases?
They increase. That causes melting/boiling points to increase as well (more energy needed to overcome these forces).
What are giant covalent substances?
Solids, atoms covalently bonded together in a giant lattice.
What are the melting and boiling points of giant covalent substances?
High melting/boiling points due to strong covalent bonds.
Do giant covalent substances conduct electricity?
Mostly don’t conduct electricity (no delocalised electrons).
Give examples of giant covalent substances.
Diamond, graphite, silicon dioxide.
What are the properties of diamond?
Diamond has four strong covalent bonds for each carbon atom, making it very hard and giving it a very high melting point. It does not conduct electricity due to the absence of delocalised electrons.
What are the properties of graphite?
Graphite has three covalent bonds for each carbon atom, forming layers of hexagonal rings. It has a high melting point, and the layers are free to slide due to weak intermolecular forces, making it soft and useful as a lubricant. Graphite conducts thermal and electrical energy due to one delocalised electron per carbon atom.
What are fullerenes?
Fullerenes are hollow shaped molecules based on hexagonal rings, but they may also contain 5 or 7-carbon rings. An example is C60, which has a spherical shape and a simple molecular structure known as Buckminsterfullerene.
What are nanotubes?
Nanotubes are cylindrical fullerenes with a high length to diameter ratio. They exhibit high tensile strength due to strong bonds and conductivity because of delocalised electrons.
What is graphene?
Graphene is a single layer of graphite.
What is metallic bonding?
Forces of attraction between delocalised electrons and nuclei of metal ions.
Bonding between a metal and another metal atom.
What is an alloy?
Mixtures of metals with other elements usually metals.
Alloys have different sizes of atoms to distort the layers so they can’t slide over each other therefore alloys are harder than pure metals.
