Strcuture and Bonding Flashcards
Whtat are the three strong chemical bonds?
Ionic, covalent and metallic
For ionic bonding the particles are …
Oppositely charged ions
For covalent bonding the particles are …
Atoms which share pairs of electrons
For metallic bonding the particles are …
Atoms which share delocalised electrons
Ionic bonding occurs in compounds formed from …
Metals combined with non-metals
Covalent bonding occurs in …
Most non-metallic elements and compounds of non-metals
Metallic bonding occurs in …
Metallic elements and alloys
The diagram for ionic bonding is …
Dot and Cross Diagram
Ionic bonding is the ——– of electrons
Transfer
Covalent bonding is the ——- of pairs of electrons
Sharing
Metal atoms —- electrons to become ———- charged ions
Lose
Positively
Non-metal atoms —- electrons to become ———- charged ions
Gain
Negatively
Which groups of metals undergo ionic bonding to achieve a full outer shell?
Groups 1 and 2
Groups 6 and 7
What is an ionic compound?
A giant structure of ions
How are ionic compounds held together?
Strong electrostatic forces of attraction between oppositely charged ions
Which ionic compound’s strcuture does this describe?
“Each sodium ion is surrounded by six chloride ions, and each chloride ion is surrounded by six sodium ions”
Sodium chloride
Ionic compounds form a ——- structure
Giant ionic lattice
Make this molecular formula an empirical formula
“C2H4”
CH2
Covalently bonded substances have —– bonds
Strong
Covalently bonded substances may consist of —– molecules
Small
Polymers have very —– molecules
Large
Diamond and Silicon Dioxide are …
Giant covalent molecules
Diamond is formed from the element ——
Carbon
In diamond, each carbon atom is covalently bonded to - other carbon atoms
4
What are the properties of diamond?
Doesn’t conduct electricity
Very high melting point
Very hard
Why can’t diamond conduct electricity?
It has no free electrons to carry a charge because all outer electrons are in covalent bonds
Silicon dioxide can be referred. to as ——
Silica
What are the properties of silica?
Hard
High melting point
What is silicon dioxide made up of?
Silicon and oxygen atoms covalently bonded
In silica, each silicon atom is bonded to - oxygen atoms
4
Try to draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane
…
The advantage of a dot and cross diagram is …
It is very clear where the electrons are coming from
The disadvantage of a dot and cross diagram is …
It doesn’t show the shape of a molecule
2D stick diagrams are bad because …
They do not show the shape of a molecule
It is unknown which electron came from which atom
The advantage of a ball and stick diagram is …
It allows us to clearly see the ions in three dimensions
A space filling diagram is good because …
It more accurately shows how closely packed each ion is
Ball and stick diagrams, and space filling diagrams are misleading in regards to the —- of a giant ionic lattice
Size
Metals consist of —– ———- of atoms arranged in a ——- pattern
Giant structures
Regular
Outer shell electrons of metal atoms are ———–
Delocalised
Delocalised electrons are free …
To move through the whole strcuture
Strong metallic bonds are formed from …
The sharing of delocalised electrons
A delocalised electron is an electron that is not …
Connected to a single atom or a covalent bond (free to move)
What are the limitations of the particle model?
There are no forces
All particles are spheres
All particles are solid
Give the 4 state symbols
s - solid
l - liquid
g - gas
aq - aqueous
Ionic compounds conduct electricity when … because …
Melted or dissolved in water because the ions are free to move
The larger the molecule, the —— the melting and boiling point
Higher
Atoms in polymers are linked with …
Strong covalent bonds
Polymers are —– at room temperature
Solids
The strucutre of a polymer is typically shown as a …
Long chain
Diamond and graphite are forms of what?
Carbon
Graphene is …
A single layer of graphite and has properties that make it useful in electronics and composites
What structure is diamond?
Giant covalent structure
In diamond, each carbon atom forms how many bonds?
Four covalent bonds with other carbon atoms
In graphite, each carbon atom forms how many bonds
Three covalent bonds with three other carbon atoms
What shaped rings are formed in graphite?
Hexagonal rings with no covalent bonds between the layers
How many electrons are delocalised in graphite
One from every carbon atom
Definition of graphene
A single layer of graphite with useful properties for electronics and composites
What was the first fullerene to be discovered?
The buckminsterfullerene
What is a cylindrical fullerene?
A carbon nanotube (very high length to diameter ratio)
What are carbon nanotubes useful for?
Nanotechnology, electronics and materials
What are fullerenes?
Molecules of carbon atoms with hollow shapes
How does the size of a cube affect the surface area to volume ratio?
As the side length decreases, SA to volume ratio increases
How small is a nanometre?
1 x 10^-9 m
List of applications of nanoparticles
Medicine, electronics, cosmetics, sun creams, deodorants and catalysts
What is a disadvantage of nanoparticles?
They can interact wih cells inside our body that cause health problems
