C2 - Bonding, Structure, and The Properties of Matter Flashcards
What is Ionic Bonding?
The electrostatic attraction between positive and negative ions.
How are ionic compounds held together?
Held together in a giant lattice.
Regular structure that extends in all directions in a substance.
Electrostatic attraction between positive and negative ions holds the structure together.
State properties of Ionic Substances.
High melting and boiling points.
Do not conduct electricity when solid.
Conduct when molten or dissolved in water.
What is important when working out a formula of an Ionic Compound?
They are electrically neutral, because positive and negative charges balance each other.
How are Ionic Compounds formed? Explain in terms of MgO case. (4 Marks)
Reaction of a metal with a non-metal.
Metal gives away its outer shell electrons to non-metal.
Mg is in Group 2, so has 2 available outer shell electrons.
O is in Group 6, so can accept 2 electrons to get a full outer shell configuration.
Mg becomes Mg^2+ and O becomes O^2-.
What is a Covalent Bond?
A shared pair of electrons between two atoms.
Describe the structure and properties of simple molecular covalent substances.
Do not conduct electricity.
Small molecules.
Weak intermolecular forces, therefore:
Low melting and boiling points.
What are Polymers?
Very large molecules with atoms linked by covalent bonds.
What are thermosoftening polymers?
They melt/soften when heated. There are no bonds between polymer chains. Weak intermolecular forces ensure that the structure is solid at room temperature.
What are giant covalent substances?
Solids, atoms covalently bonded together in a giant lattice.
High melting and boiling points - strong covalent bonds.
Mostly don’t conduct electricity.
Give example of Giant Covalent Substances.
Diamond
Graphite
Silicon dioxide
Describe and explain the properties of Diamond.
Four, strong covalent bonds for each carbon atom
Very hard
Very high melting/boiling points
Insulator
Describe and explain the properties of Graphite.
Three covalent bonds for each carbon atom
Layers of hexagonal rings
High melting point
Layers free to slide as weak intermolecular forces between layers
Conducts thermal and electricity.
Describe and explain the properties of Fullerenes.
Hollow shaped molecules
Based on hexagonal rings but may have 5/7 carbon rings
Has spherical shape, simple molecular structure (Buckminsterfullerene)
Describe and explain the properties of Nanotubes.
Cylindrical fullerene with high length to diameter ratio
High tensile strength
Conductivity
What is Graphene?
A single layer of graphene.
What is Metallic Bonding?
Forces of attraction between delocalised electrons and nuclei of metal ions.
What are Alloys?
Mixtures of metal with other elements, usually metals.
What are Alloys harder than pure metals?
Different sizes of atoms distorts the layers, so they can’t slide over each other, therefore alloys are harder than pure metals.
What are the limitations of the simple model?
There are no forces between spenders and atoms, molecules, and ions are solid sphere - this is not true.
What does the amount of energy needed to change state from solid to liquid or liquid to gas depend on?
The strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance.
A pure substance will melt or boil at…?
A fixed temperature.
A mixture will melt over a range of temperature.
What are the 3 states of matter?
Solid
Liquid
Gas
State 4 uses of Nanoparticles.
Medicine
Electronics
Deodorants
Sun creams
What are fine and coarse particles?
Fine particles: 100-2500nm diameter.
Coarse particles: 2500-10^5nm diameter.
Why do Nanoparticles have different properties to those for the same materials in bulk?
High surface area to volume ratio.
