Structure And Bonding Flashcards
What is ionic bonding?
Ionic bonding is a chemical bond that involves the electrostatic attraction between oppositely charged ions. It is between a metal and a non metal
What is the structure all ionic compounds form?
Giant Ionic lattices
What is a lattice?
An ionic structure where ions are arranged regularly with no gaps.
What holds together ions in a lattice?
Electrostatic forces of attraction
What state must ionic substances be in to conduct electricity?
Molten or dissolved
What are properties of ionic compounds?
- Solid at room temperature
- Conduct electricity when molten improve dissolved
- Soluble in water
- Very high melting points
Why can ionic substances conduct electricity when molten or dissolved?
As the charged particles are free to move around (as the lattice is broken) and so can carry and charge
Why do ionic substance have high melting and boiling points?
The strong electrostatic attractions between oppositely charged ions require a lot of energy to break apart
What is covalent bonding?
When two non metals react, both wanting to gain electrons to make a full outer shell, so they share a pair of electrons
How man bonds do non metals have?
The same number of electrons on their outer shell
What are properties of simple molecular compounds?
- Low melting and boiling points
- Do not conduct electricity (other then water)
- Low density
- Soluble
What are properties of giant molecular compounds?
- High melting and boiling points
- Generally do not conduct electricity
- High density
- Insoluble
Why do simple molecular have low melting and boiling points?
A structure when only the weak intermolecular forces between molecules are broken (not strong covalent one). So only small amounts of energy are needed to break the weak forces.
Why can’t simple molecular conduct electricity?
As there are no free charged particles (only ions or electrons) to allow a current to flow.
What is the structure of polyethene?
Between the carbon atoms there are strong covalent bonds and between the layers there are weak intermolecular forces
Why do polymers have high melting and boiling points?
As the longer the chain length, the more intermolecular forces between the monomers, meaning more energy is needed to break them apart
What are allotropes?
Allotropes are different structural forms of the same element
What are some properties of the allotrope diamond?
- Hard
- High letting point
- Shiny
- Does not conduct electricity
What are some properties of the allotrope graphite?
- soft
- high melting point
- black
- does conduct electricity
Why does diamond have a large tetrahedral structure?
As each carbon forms four covalent bonds with other carbon atoms
What is the stricture of graphite?
Each carbon forms three covalent bonds with other carbon atoms. This forms hexagonal rings which have intermolecular forces between the layers
Why is diamond hard?
Because each carbon is bonded covalently to 4 other carbon atoms meaning it is in a tetrahedral structure - difficult to break
Why cannot diamond conduct electricity?
As all electrons are used within covenant bonds so there are no free electrons to carry a charge.
Why does diamond have such a high melting point?
As they are giant covalent molecules (macromolecules). This means they have strong electrostatic forces that require a lot of energy to break apart.
Why is graphite soft?
As it has weak intermolecular forces between layers meaning they can slide and break easily.
What can graphite conduct electricity?
As each carbon atoms makes 3 bonds yet each carbon atoms has 4 electrons, so this leaves a free electron that can carry a charge.
What does graphite have a high melting and boiling point?
As it is giant covalent structure (macromolecules) meaning it has strong covalent bonds that require lots of energy to break apart.
What is Graphene’s structure?
Large sheet of carbon (giant covalent structure)
What is fullerenes structure?
A spherical allotrope of carbon which is covalently bonded to 3 carbons.
Why does Graphene have exceptional strength?
Due to strong covalent bonds
What is Graphene an extremely light material?
As it is only 1 atom thick (2D)
Why is Graphene an electrical conductor?
Due to electrons moving across its surface and that it can be rolled into nanotubes
Why does fullerene have a low melting point?
Due to weak intermolecular forces between molecules
Why does fullerene conduct electricity
Due to delocalised electrons that can carry a charge
What are some properties of metals?
- Conducts electricity
- high melting and boiling points
- malleable
- ductile
- sonorous
What is the structure of a metal?
Rows of metal cations (positive ions) held together by a sea of delocalised electrons
What does delocalised mean?
Not fixed in a certain position and free to move around
What happens if there are mor delocalised electrons?
The stronger the metal is as the positive to negative attraction is a lot greater
Why is metallic bonding strong?
As the cations and electrons are strongly attracted to each other. This means a lot of energy is needed to break this bond and cause a change in state
Why can metals conduct electricity?
As the delocalised electrons are free to more. This means when a potential difference is applied the electrons flow in one direction.
Why are metals malleable?
As when a force is applied, the regularly arranged electrons are free to move over one another. Yet, ions are still held together by delocalised electrons so do not fully break
When do ionic bonds occur?
Between a metal and a non-metal, between a cation and an anion come together
What happens to the ending of a non-metal when an ionic bond is formed?
It changes to -ide
