C3 Flashcards
What are ions
Charged particles
Why do atoms want to lose or gain electrons to form ions?
To form a full outer shell and become stable
What are positive ions called
Cations
What are negative ions called
Anions
What is ionic bonding
Transfering of electrons
What happens when a metal and non metal react togehter
Metal atoms loses electrons to form a positively charged ion and the non metal gains these electrons forming a negativelt chwrged ion. These oppositely charged ions are strongly attrachted to one another by electrostatic forces. This attraction is called ionic bond
How do to show how ionic compounds are formed ?
Dot and cross diagram (pg113)
What structure do ionic compounds have
Gaint ionic lattice. The ions form a closely packed regular lattice arrangment and there are very strong electrostatic forces of attraction between oppositely charged ions
What are the properties of ionic compounds?
They all have high melting points, many strong bonds between ions, takes alot of energy to overcome attraction. When they are solid, can’t conduct electricity and when they melt they are free to move and they carry electrical charge.
How do you work out the empirical formula of an ionic compound?
Look at diagram to work out what ions are in the compound. Then work out the charges in which the ions will form. Then balance the charges (bottom pg114)
When are covalent bonds created
When non metal atoms bond together sharing pair electrons to make covalent bonds
What makes covalent bonds very strong
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces
What does each single covalent bond provide
1 extra shared electron for each atom
Why is O2 a gass at room temperature
Because most molecular substances are gases or liquid at room temperature because very little energy is required to overcome these forces
Why does methane have a higher boiling point than hydrogen
Because the more intermolecular forces, the more energy is needed to break them down therefore the melting and boiling point increases
Why does nitogen not conduct electricity
Because molcular compounds do not conduct electricity because they arn’t charged so there are no free electrons or ions
What is a polymer
large molecule made up of repeating subunits known as monomers
How are all atoms in a polymer joined
Strong covalent bonds
Why do intermolcular forces have lower boiling points than ionic or covalent bonds
Intermolecular forces are weaker than ionic and covalent bonds
How are giant covalent bonded to eachother
Strong covalent bonds
Do giant covalent points have a higher or lower melting point
High because alot of energy is required to break them diwn
Do giant covalent structure conduct electricity and if so why
No because they have no charged particles
What are allotropes
Different structural forms of the same element in the same physical state
What structure does diamond have
Giant covalent structure
In graphite, how many covalent bonds are formed
3
In diamond, how many covalent bonds are formed
4
Why does graphite have a high melting point
Covalent bonds need alot of energy to break down
Are there covalent bonds between layers in a graphite and what does this mean
No covalent bonds between layers and held together weakly meaning they are free to move over eachother. Making the graphite soft and slippery - ideal as a lubricating metal
What is the name of 1 graphite
Graphene
What does graphene contain and what does this mean
Delocalised electrons meaning graphene can conduct electricity
What is a fullerene
Molecules of carbon shaped like closed tubes or hollow balls
What was the first fullerene to be discovered
Buckminsterfullerene c60- hollow sphere
3 thing fullerenes can be used to do
1) cage other molecules - fullerene structure forms around an atom or molecule so this could be used to deliver a drug in the body
2) huge surface area so help make industrial catalysts
3) greats at making lubricants
What are electrons in the outermost shell of metals and what does this mean
Delocalised meaning they are free to move around the shell. Strong forces of electrostatic attraction between positive metal ions and negative electrons
What is metallic bonding
force of attraction between these free-moving (delocalised) electrons and positive metal ions
What produces the properties of metals
Delocalised electrons
Why are most metals a solid at room temp
Because electrostatic forces between metal atoms and the delocalised electrons are very strong and need alot of energy to be broken down
Why are metals good conductors of electricity and heat?
Delocalised electrons carry charged and thermal energy meaning they are good conductors of heat and electricity
What makes the metals malleable and what does this mean
Most metals can slide over eachother making the metals malleable meaning they can be bent, hammered, rolled
What are alloys
Mixture of 2 or more metals
Why are pure metals no right for certain jobs
Because pure metals are not strong enough so they are mixed with other metals so they are stronger called alloys
Limitations of the particle model:
It assumes that psrticles are made up of solid spheres with no forces between them, however the particles that make up substances are atoms, molecules or ions.
Ionic solid features:
-Ions are fixed in position in a giant lattice
-they vibrate but can’t move
-it doesnt conduct electricity
Molten ionic compound features:
-high temperature which provides energy to overcome strong forces of attraction
-ions are free to move
-it does conduct electricity
Ionic compound in solution:
-Water molecules seperate ions from the lattice
-ions are free to move around within the solution
-it does conduct electricity
Properties of polymers
The intermolecular forces between polymer molecules are larger than between simple covalent molecules, so more energy’s needed to break down. This means most polymers are solid at room temperature.
The intermolecular forces are still weaker than ionic/covalent bonds, so have lower boiling points than ionic/giant molecular compounds
Structure of silicon dioxide
