Unit 1.5 - Solid Structures Flashcards
What are ionic solids made up of?
Oppositely charged ions packed around each other
What’s made up of oppositely charged ions packed around each other?
Ionic solids
What does oppositely charged ions being packed around each other in an ionic solid do?
Maximises the electrostatic attraction between oppositely charged ions
Minimises repulsion between ions with the same charge
Ensuring maximum bond energy
How is maximum bond energy ensured in an ionic solid?
Through the oppositely charge ions being packed around each other, which…
Maximises electrostatic attraction between oppositely charged ions
Minimises repulsion between ions with the same charge
How many Na+ cations surround each Cl- anions and vice versa in sodium chloride?
6
Which salt has 6 cations surrounding the anions and vice versa?
Sodium chloride
Crystal coordination number of sodium chloride
6:6
Which salt has a crystal coordination number of 6:6?
Sodium chloride
Crystal coordination number
The number of anions around each cation in an ionic lattice and vice versa
The number of anions around each cation in an ionic lattice and vice versa
Crystal coordination number
What’s the Crystal coordination of sodium in sodium chloride?
6
How many Cl- anions surround each Cs+ cation and vice versa in caesium chloride?
8
Crystal coordination number of caesium chloride
8:8
Which sal has a crystal coordination number of 8:8?
Caesium chloride
Why do sodium chloride and caesium chloride have different crystal coordination numbers?
Cs+ cation is larger than that of Na+
=more room to accommodate a greater number of anions
Does Cs+ or Na+ have more room to accommodate a greater number of anions? Why? Why is this relevant?
Cs+ as it’s larger, therefore it has a higher crystal coordination number
Is Cs+ or Na+ a bigger cation and what does this mean?
Cs+ is larger, so it has more room to accommodate a greater number of anions, so it has a larger crystal coordination number
Crystal
Atoms or molecules joined together in a repeating pattern to create a certain shape
Atoms or molecules joined together in a repeating pattern to create a certain shape
Crystal
What are the properties of ionic compounds determined by?
The strength of the electrostatic forces between the ions
What do the strength of the electrostatic forces between ions determine?
The properties of ionic compounds
Properties of ionic compounds
High melting and boiling points
Electrical insulators as solids
Electrical conductors when molten or dissolved in water
Brittle
Soluble in water (some)
What type of compounds have the following properties?
High melting and boiling points
Electrical insulators as solids
Electrical conductors when molten or dissolved in water
Brittle
Soluble in water
Ionic compounds
Why do ionic compounds have high melting and boiling points?
Due to the strong electrostatic attraction between the oppositely charged ions which require a lot of energy to overcome
What do the strong electrostatic attraction between the oppositely charged ions which require a lot of energy to overcome cause ionic compounds to have?
High melting and boiling points
Why are ionic compounds electrical insulators as solids?
Ions are in fixed positions and can’t move
What do ions being in fixed positions when solid cause ionic compounds to be?
Electrical insulators as solids
When are ions in a fixed condition in ionic compounds?
As solids
Why are ionic compounds electrical conductors when molten or dissolved in water?
Ions are free to move and carry a charge when voltage is applied
What do ionic being free to move and carry a charge when molten or dissolved in water in an ionic compound cause it to be?
Electrical conductor
When can ions carry a charge to be an electrical conductor when molten?
When voltage is applied
When are ionic compounds electrical conductors?
When molten or dissolved in water
When are ionic compounds electrical insulators?
As solids
What are ionic compounds as solids?
Electrical insulators
What are ionic compounds when molten or dissolved in water?
Electrical conductors
Why are ionic compounds brittle?
Due to repulsion between like charged ions when the layers of ions are shifted by a large enough force
What is caused by repulsion between like charged ions when the layers of ions are shifted by a large enough force in an ionic compound?
They’re brittle
Why are certain ionic compounds soluble in water?
When the solid dissolves, the ions are surrounded by water molecules, which are attracted to the ions due to the water molecules having a permanent dipole
Why are water molecules attracted to (some) ions?
Due to water molecules having a permanent dipole
What does the fact that water molecules have a permanent dipole cause with ions and what does this lead to?
When an ionic solid is dissolved, the ions are surrounded by water molecules, which are attracted to the ions due to the water molecules having a permanent dipole - solubility in water
Which ionic compounds are soluble in water?
All group I compounds
All nitrate compounds
Most halide compounds
What’s special about the following ionic compounds?
All group I compounds
All nitrate compounds
Most halide compounds
Soluble in water
What are giant covalent structures made up of?
Atoms that form multiple covalent bonds to other atoms forming a giant lattice structure
What are formed of atoms that form multiple covalent bonds to other atoms forming a giant lattice structure?
Giant covalent structures
Lattice
Consistently repeating pattern of atoms
Consistently repeating pattern of atoms
Lattice
Give 2 examples of giant covalent structures?
Diamond and graphite
What are diamond and graphite examples of?
Giant covalent structures
What are diamond and graphite forms of?
Elemental carbon
Name two forms of elemental carbon
Diamond and graphite
What are diamond and graphite to carbons?
Allotropes
Name two allotropes of carbon
Diamond and graphite
Allotrope
Different structures of the same element
Different structures of the same element
Allotropes
How many carbon atoms does each carbon atom bond to in diamond?
4
What bonds with 4 others similar to it in diamond and graphite?
Carbon atoms
Which allotrope of carbon forms 4 strong bonds to other carbon atoms?
Diamond
What type of structure does diamond have?
Tetrahedral arrangement, forming a giant 3D structure
Which allotrope of carbon has a Tetrahedral arrangement, forming a giant 3D structure?
Diamond
How many covalent bonds can carbon form?
4
How many bonds are made by each carbon atom in graphite?
3
Which allotrope of carbon forms 3 bonds with other carbon atoms?
Graphite
Describe the structure of graphite
Hexagonal layers (only 1 layer thick), which are held together by weak Van der Waal forces
Which allotrope of carbon has hexagonal layers which are only 1 layer thick?
Graphite
What are the hexagonal layers of graphite held together by?
Weak Van der Waals forces
What are the properties of giant covalent structures determined by?
The strength of the covalent bonds between the atoms
What is determined by the strength of the covalent bonds between the atoms?
The properties of giant covalent substances
What are the properties of both diamond and graphite?
High melting and boiling points
Insoluble
What are the following properties for?
High melting and boiling points
Insoluble
Both diamond and graphite
Why do both diamond and graphite have high melting and boiling points?
Each carbon atom has 3 or 4 strong covalent bonds, which require a lot of heat energy to overcome
What does each carbon atom having 3 or 4 strong covalent bonds, which require a lot of heat energy to overcome mean for both diamond and graphite?
High melting and boiling points
Why are both diamond and graphite insoluble?
No charged particles capable of interacting with the permanent dipole of water molecules
What do no charged particles capable of interacting with the permanent dipole of water molecules mean for both diamond and graphite?
Insoluble
Which properties are specific to just diamond?
Very hard
Electrical insulator
What do the following properties apply for?
Very hard
Electrical insulator
Diamond (just diamond)
What does diamond being “very hard” mean for it?
It’s difficult to scratch
Why is diamond very hard (difficult to scratch)?
Due to each carbon atom being bonded to 4 others, with strong covalent bonds.
This holds the atoms together in a rigid 3D structure.
What does each carbon atom being bonded to 4 others, with strong covalent bonds mean for diamond?
Very hard (difficult to scratch)
Why is diamond an electrical insulator?
Due to there being no delocalised electrons within the structure (can’t carry voltage)
What does diamond having no delocalised electrons mean for diamond and why?
Electrical insulator - can’t carry voltage
Which properties are specific to graphite?
Soft and slippery
Electrical conductor
What are the following priorities for?
Soft and slippery
Electrical conductor
Just graphite
Why is graphite soft and slippery?
Due to the layers of carbon atoms (which are only attracted to each other with weak intermolecular forces) being able to easily slide over each other
What do the layers of carbon atoms being easily able to slide over each other with their weak intermolecular forces mean for graphite?
It’s soft and slippery
What is graphite used in and why?
Pencils and lubricant - soft and slippery
What is used in pencils and lubricant and why?
Graphite - soft and slippery
Why are layers of carbon atoms in graphite easily able to slide over each other?
They’re only attracted to each other with weak intermolecular forces
Why is graphite an electrical conductor?
One non-bonding electron in the valence shell of each carbon atom + these become delocalised between the layers and can carry voltage
What does one non-bonding electron in the valence shell of each carbon atom + these become delocalised between the layers and can carry voltage mean for graphite?
Electrical conductor
Why can the non-bonding let Ron in graphite carry a voltage?
As it’s delocalised between the layers
What does the non-bonding electron in graphite do? What does this mean?
Becomes delocalised between the layers, so it can carry voltage and is an electrical conductor
What do simple covalent structures consist of?
Simple covalent molecules held together in a lattice structure by weak intermolecular forces (Van der Waal forces)
What consist of simple covalent molecules held together in a lattice structure by weak intermolecular forces (Van der Waal forces)
Simple covalent structures
What holds simple covalent molecules together in a lattice?
Weak intermolecular forces (Van der Waal forces)
What are iodine molecules held together by?
Van der Waals forces
Which is strongest - the Van der Waal forces between iodine molecules or chlorine molecules and why?
Iodine molecules as the strength of Van der Waal forces increase with molecular size
What increases the strength of Van der Waal forces?
Increased molecular size
How are I2 molecules positioned in an iodine structure and how can we see this?
Looking down the top of the structure, they’re seen to be positioned in layers
Which bond is strong and which bond is weak in iodine?
Covalent bond between atoms = strong
Van der Waal forces = weak
Describe the covalent bond between 2 iodine atoms within a molecule
Strong
What type of bond is between 2 iodine atoms?
Covalent
Which bond is strong in iodine?
The covalent bond between 2 iodine atoms within the molecule
Which bond is weak in iodine?
Van der Waal forces
Describe the Van der Waal forces in iodine
Quite weak
What do the weak Van der Waal forces in iodine cause it to do?
Sublime very easily
What causes iodine to sublime very easily?
Weak Van der Waal forces
Sublimes
Moves from a solid to gas state without becoming a liquid
Moves from a solid to gas state without becoming a liquid
Sublimes
Name two different molecules who have covalent bonding holding the atoms together
I2 and H20
How are H20 molecules held together?
By hydrogen bonding
How does hydrogen bonding form between a H20 molecules?
Between the partially positive hydrogen atoms and the lone electron pairs on the oxygen atoms
What type of structure do H20 molecules in ice form? Why?
Tetrahedral structures due to their strong intermolecular bonds (hydrogen bonds)
Describe the structure of H20 molecules in ice
Tetrahedral, rigid and spaced out
Describe the properties of ice v.s water
Ice - less dense and takes greater volume
What’s the most dense - ice or water? Why?
Water due to ice having an unusual rigid and spaced out tetrahedral stucture
What takes greater volume - ice or liquid water? Why?
Ice due to its unusual tetrahedral structure that’s rigid and spaced out
Why is ice less dense and takes a greater volume than liquid water?
Due to its unusual tetrahedral structure that’s both rigid and spaced out
Why do ice and iodine have certain properties in common?
Due to the fact that they both have simple covalent stuctures
What are the following properties of?
Low melting and boiling points
Soft
Electrical insulators
Simple covalent solids
What are the properties of simple covalent solids?
Low melting and boiling points
Soft
Electrical insulators
Why do simple covalent solids have low melting and boiling points?
Weak intermolecular forces that require very little heat to overcome
What does having intermolecular forces that require very little heat to overcome cause in simple covalent solids?
Low melting and boiling points
Why are simple covalent solids soft?
Due to weak intermolecular forces that only require a small force to break
What does having weak intermolecular forces that only require a small force to break cause in simple covalent solids?
They’re soft
Why are simple covalent solids electrical insulators?
Lack of any mobile charged particles (no delocalised electrons)
What does a lack of any mobile charged particles (delocalised electrons) in simple covalent solids cause?
They’re electrical insulators
Describe the solubility of iodine in water and give an explanation
Sparingly soluble
Van der Waals forces between I2 molecules are not strong enough to break up the hydrogen bonding between water molecules
Describe a metallic structure
They have a regular arrangement of metal cations (+ ions) closely packed together and surrounded by a “sea” of delocalised electrons
Which structure is being described here?
“They have a regular arrangement of metal cations (+ ions) closely packed together and surrounded by a “sea” of delocalised electrons”
Metallic stucture
What has a regular arrangement and what is delocalised in a metallic structure?
Regular arrangement - metal cations (+ ions)
Delocalised - electrons
Why is the “sea” of delocalised electrons formed in metallic structures?
The valence electrons (outer electrons) are so weakly bound to their atoms that these electrons can move freely throughout the lattice of metal ions
Which electrons are weakly bound to their atoms in metallic structures to cause the “sea” of electrons?
Valence electrons
What holds a metal structure together?
The strong electrostatic attraction between the metal cations and the delocalised electrons
What type of force holds a metal structure together and between what?
Strong electrostatic attraction between the metal cations and the delocalised electrons
Do all metals have similar properties?
Yes
What are the properties of metallic structures?
Good conductors of heat and electricity
Malleable
Ductile
Which do the following properties ply for?
Good conductors f heat and electricity
Malleable
Metallic stuctures
Why are metallic structures good inductors of heat and electricity?
Delocalised electrons can carry thermal or electrical energy through the lattice of metal ions
What do delocalised electrons being able to carry thermal or electrical energy through the lattice of metal ions cause in metallic structures?
They’re good conductors of heat and electricity
Why are metallic structures malleable?
Layer of metal cations can easily slide over each other, and delocalised electrons move with the ions to maintain metallic bonding
What does the layer of metal cations being able to easily slide over each other, and delocalised electrons moving with the ions to maintain metallic bonding cause in metallic structures?
They’re malleable
Malleable
Able to change shape without permanently breaking
Able to change shape without permanently breaking
Malleable
What varies in metallic structures?
Melting and boiling points
In what type of structure to melting and boiling points vary?
Metallic sturctures
What do the melting and boiling points depend on in metallic structures?
The number of delocalised electrons per atom
What does the number of delocalised electrons per atom decide in metallic structures?
The melting and boiling points
What’s the trend in terms of the melting and boiling points of metallic structures?
The more delocalised electrons per atom, the higher the melting and boiling points
What does a higher number of delocalised electrons per atom mean in a metallic structure?
Higher eating and boiling points, and also a harder material
What makes a metallic material harder?
Having a high number of delocalised electrons
What is at the corner of a cube representing iodine’s structure?
An iodine molecule
What does iodine sublime to and from?
Black solid ——> purple vapour
What are the properties of ice essential for?
Life
Name a structure that is shiny and explain why
Metals - electrons on the surface reflect light
Draw a metallic structure
(See notes)
Draw iodine’s structure (simple covalent)
(See notes)
Draw an ionic solid structure
(See notes)
Why are metallic structures ductile?
Metal cations can slide over each other’s but are still held together by the delocalised electrons to maintain metallic bonding
What does the fact that metal cations can slide over each other’s but are still held together by the delocalised electrons to maintain metallic bonding mean for metallic structures?
Ductility
Which metal is used in overhead power cables and why as opposed to a different material?
Aluminium - is an electrical conductor
(Not copper - its too dense for the thickness required)
Why is copper not used in overhead power cables?
Too dense for the thickness required
What’s aluminium used for?
Overhead power cables
What type of structure does silicon have?
Giant covalent
Why does having more delocalised electrons in a metal give it a higher melting and boiling point?
Stronger metallic bond
What makes a metallic bond stronger?
More delocalised electros in the atom
What makes a bond covalent?
-no difference in electronegativity
-all bonding shared equally between atoms
Explain why ice and water have different densities
Hydrogen bonding exists in both water and ice but it extends throughout the whole structure in ice
The ice hydrogen bonds hold the molecules together in an open tetrahedral structure
The molecules are further apart in ice than they are in water, so ice is less dense than water
Which other compound has a giant covalent structure similar to diamond?
Silicon dioxide
Silicon dioxide structure
Giant covalent
3 elements with giant covalent structures
Silicon dioxide
Diamond
Graphite
List the following in order from lowest to highest melting temperature:
Graphite, metal, iodine, ice, caesium chloride, sodium chloride
Ice
Iodine
Metal
Caesium chloride
Sodium chloride
Graphite
What has the highest melting temperature- iodine or ice?
Iodine
Why is graphite used in pencils?
Weak forces between layers are easily broken
Layers can slide over each other and can be removed to transfer onto paper
What leads to a stronger metal and why?
More valence electrons = stronger metallic bond
Which ions are bigger in sodium chloride?
Chloride ions
Which ions are bigger in caesium chloride?
Neither
