Chemical Bonding (seneca) Flashcards
- types of bonds - ionic bonds - ionic compounds - covalent & metallic bonds - representing covalent bonds - states of matter - changing state - chemical properties - molecular forces & polymers -
What is ionic bonding?
Ionic bonding involves an attraction between oppositely charged ions.
Ionic bonds are found in compounds made of metals and non-metals.
What is covalent bonding?
Covalent bonding involves 2 atoms sharing 1 or more pairs of electrons.
Covalent bonds are found in most non-metal elements and in non-metal compounds.
What is metallic bonding?
Metallic bonding involves an attraction between positively charged ions and negatively charged delocalised electrons.
Metallic bonds are found in metals and alloys (mixtures of metals and other substances).
Positive ions are also called …
cations
The metals in Group - and - can easily lose electrons to become positively charged ions.
1 and 2
Negative ions are also called…
anions
The —— in Group - are most likely to gain electrons to fill up their electron shell and become negatively charged.
non-metals
7
Ions can be made up of (2)
- 1 atom (e.g. F-).
- Combinations of atoms with an overall charge (e.g. SO42-).
Calcium is in group 2 of the periodic table. What happens to a calcium atom when it becomes an ion?
Because calcium is a Group 2 metal, there are 2 electrons in its outer shell.
Calcium atoms remove these 2 electrons to achieve a full outer shell containing 8 electrons, and in doing so become Ca2+ ions.
Non-metal atoms ——– electrons resulting in the formation of ——-
ions.
always gain
negative
In ionic bonding, a 1. transfers electrons to a 2.
1.metal atom
2.non-metal atom
The —— number in the periodic table tells you the number of electrons in an atom’s outer electron shell.
group
Noble gases already have a —– outer shell. Noble gases are ——– and ——- form ionic bonds with other elements.
full
inert
don’t normally
what are ionic lattices?
ionic lattices are are giant structures that are held together by strong electrostatic forces between the positive and negative ions.
Ionic compounds form when 1 transfer their outer electrons to 2 at the same time. The resulting oppositely charged ions are held together in 3
1.millions of metal atoms
2.millions of non-metal atoms
3.ionic lattices.
the———- are called ionic bonds and they extend in——-
electrostatic forces
all directions
What type of structure are ionic lattices?
giant structures
What do we call the electrostatic forces that hold ionic lattices together?
ionic bonds
give an example of small covalent molecules
water
Covalent bonds are strong because …
the shared electrons are attracted to the nucleus of both atoms
give an example of large covalent molecules
polymers such as polyester and silk
give an example of giant covalent structures
diamond
Metallic bonds are the
electrostatic attractions between positive ions and negative delocalised electrons.
The metallic bond structure is a
regular lattice of positive ions (cations) in a ‘sea’ of delocalised electrons.
in metallic bonding, Metals are
giant structures of regularly arranged atoms
in metallic bonding, delocalised electrons are …
NOT bound to an atom and are free to move around within the lattice.
Delocalisation happens because
metal atoms have a small number of electrons in their outer shells.
The electrostatic attractions found within metals are between ————and ——–
positive metal ions
delocalised electrons.
Dot-and-cross diagrams can be used to represent
covalent bonds and to show the sharing of electron pairs.
Double and triple bonds are normally —– and require —- energy to break.
stronger
more
what are the three types of covalent bonds
single covalent bonds
double covalent bonds
triple covalent bonds
A limitation of the dot and cross with shells diagram is that
it shows electrons differently for each atom, when they are actually exactly the same.
A limitation of the ball and stick diagram is that …
atoms are much closer together than the diagram show
what are the different covalent bond diagrams
Dot-and-cross without shells
Dot-and-cross diagram with shells
Line diagram
Ball-and-stick diagram
Which type of bonding involves an attraction between positively charged ions and negatively charged delocalised electrons?
metallic bonding
Why do electrons become delocalised in metals?
Because the electron shells in metal atoms overlap.
A 1 reactive metal (one that forms positive ions more easily) can displace a 2 reactive metal from a compound.
1.more
2.less
what is a displacement reaction?
A more reactive metal (one that forms positive ions more easily) can displace a less reactive metal from a compound.
In solids, particles are…
very close together and vibrate in a fixed position.
Solids have a —– shape and volume.
fixed
When solids are heated, the particles …
vibrate more intensely
In liquids, particles are
very close together but they move and flow randomly past one another.
Liquids have a —– volume but…
fixed
can change shape and fill a container
When liquids are heated,
the average speed of particles increases.
In gases, particles are —— and move …
far apart
randomly in all directions.
Gases —– shape and volume to fill whatever container they are in.
change
When gases are heated,
the average speed of particles increases
what are The ‘Simple Sphere’ Model disadvantages
-Forces between particles aren’t shown.
-It’s impossible to know how strong these forces are and how much energy is needed to overcome them.
-Shows particles as spherical when they actually are not.
-Particle collisions aren’t as simple as the model suggests.
-Shows particles as solid when they actually are not.
-Particles don’t ‘bounce off’ each other like snooker balls, as this model suggests.
the amount of energy required for substances to change state depends on whether …
the forces between their particles are strong or weak
substances with strong forces have a — melting and boiling points
high
substances with weak forces have a — melting and boiling points
low
What do we call the letters that tell us the state of matter of substances in a chemical equation?
state symbols
What process converts particles from a solid to a gas?
sublimation
what is a giant ionic lattice
Structure formed by ionic compounds
To break ionic bonds,
significant energy is needed to overcome the electrostatic forces between the ions and electrons in the lattice.
Because of this, the melting and boiling points of ionic compounds is …
high
When solid, the ions in the lattice are fixed in place.This means that …
charges cannot flow, so electricity cannot be conducted.
When molten, or dissolved in water, the ions in the lattice can
move freely.
Small covalent molecules are held together by
strong intermolecular forces (forces within a molecule) called covalent bonds.
Intermolecular forces are….
forces between different molecules.
Lots of small covalent molecules can be held together by …
intermolecular forces.But these intermolecular forces are weak and easy to break.
intermolecular forces are weak and easy to break. This means small covalent molecules have —- melting and boiling points . They’re often —– or —— at room temperature.
low
liquids or gases
Small molecules have —— intermolecular forces.
This means that small molecules have —- melting and boiling points.
weak
low
Small molecules don’t contain ——— electrons.
Because of this, they ——- conduct electricity.
delocalised
cannot
Cl2 (the diatomic molecule of chlorine) is a small molecule with —–intermolecular forces between its molecules.
Chlorine is a —– at room temperature.
weak
gas
Bigger molecules —– other molecules with stronger intermolecular forces. This means that they have —— melting and boiling points than small molecules.
attract
higher
Bigger molecules don’t contain ——— electrons, and so —— conduct electricity.
delocalised
can’t
Sucrose is made of 45 atoms and has the formula C12H22O11.
Although sucrose is a simple molecule, its size means that its intermolecular forces are ———– for it to be —— at room temperature.
strong enough
solid
Graphite is a ————– that has a —— melting point than methane.
giant covalent structure
higher
Polymers are …
large, chain-like molecules that can extend for thousands of atoms.
Polymers are held together by:
-Strong covalent bonds between atoms in molecules.
-Weak intermolecular forces between molecules.
Because of the large size of polymer molecules, the…
This means that…
- intermolecular forces add up to be quite strong.
- polymers are usually solid when at room temperature.
Many polymers melt easily because …
the intermolecular forces remain less strong than chemical bonds.
Which of these is strongest?
covalent bonds
intermolecular forces in small molecules
intermolecular forces in large molecules
covalent bonds
Polymers are made up of …
Because of this,
repeating units
we can show their chemical structure as a unit that is repeated lots of times.
The ‘n’ in the bottom right of the polymer tells us …
how many times the unit is repeated to create the larger polymer molecule.
The sum of intermolecular forces between smaller molecules is
small
The sum of intermolecular forces between bigger molecules is —— than the sum of intermolecular forces between smaller molecules
greater
Why are intermolecular forces stronger in polymers than small molecules?
polymers are bigger
Giant covalent structures don’t have a specific formula because
the structure can be any size.
in theory, giant covalent structures can continue —– - a diamond may have —————————— atoms.
forever
50,000 or 1,000,000,000 carbo
High temperatures and significant energy are required to ——- the structure’s covalent bonds.
break
Giant covalent structures exist as
1 large structure or molecule.
There are no intermolecular forces in giant covalent structures because…
there is only 1 molecule.
Pure metals have —- structures with strong electrostatic forces between …
- giant
- positive ions and delocalised electrons.
Because the ions are arranged in—–, pure metals …
layers
easily move over each other when a force is applied.
pure metals are —- and ——-
soft and malleable
There are —— electrostatic forces between the positive metal ions and the negative delocalised electrons.
strong
when there are strong electrostatic forces, there are — melting and boiling points.
high
all ions in pure metal are the —– size
same
An alloy is a combination of
2+ elements, where at least 1 is a metal.
The ions of the different elements in alloys are —— sizes
different
Because the ions are —— sizes in alloys,it makes it ….
different
harder for the layers to slide across each other when a force is applied to the alloy.
alloys stronger than pure metals because,as it is
harder for the layers to slide across each other when a force is applied to the alloy.
alloys are used in ———– because…
construction
they are harder and stronger
Metals are good conductors of electricity because …
their delocalised electrons can carry a charge within the structure.
The same delocalised electrons can also carry —- energy within the structure.
heat
The electrons in metals move from the 1 to the 2.
1.negative terminal
2.positive terminal
Properties of alloys (3)
- Mixture of 2+ elements
- Harder than pure metals
- Layers are distorted
Diamond ——- an electrical conductor because there are …
is NOT
no delocalised electrons in the diamond structure
A —– energy is needed to break strong covalent bonds.
lot of
Diamond has lots of ———– bonds. This means that diamond has a —- melting point.
strong covalent
high
There are lots of strong covalent bonds in diamond. This makes it very soft/hard.(choose one)
very hard
Because diamond is hard, it is used as a …
cutting tool to cut other materials.
Every carbon atom in diamond is bonded to - other carbon atoms by …
4
strong covalent bonds.
Graphite is an —— of carbon
allotrope (form)
Every carbon atom in graphite is bonded to - other carbon atoms by ———.
This creates a …
3
strong covalent bonds
giant covalent structure.
The carbon atoms form (graphite) layers of ——, with ——- keeping the layers together
hexagonal (6-sided) rings
weak intermolecular forces
The layers can —– slide over one another, so graphite is very soft/hard
easily
soft
graphite is useful as a …
lubricant and as pencil ‘lead’.
Each carbon atom forms ? bonds.
This means that there is ! delocalised electron from …
?. 3
!.1
every carbon atom
graphite is a — electrical conductor
good
Each carbon atom has …
a delocalised electron
Graphene is an ——- of carbon
allotrope (form)
Graphene is a —— so it also conducts electricity because …
single layer of graphite
of the carbon atoms’ delocalised electrons.
Graphene can/cannot conduct electricity
can
Graphene has a thickness of…
just 1 atom (1 layer).
graphene is almost a –dimensional structure, and so graphene is …
2
very light.
in graphene, the —– covalent bonds between carbon atoms mean that it is also very …
strong
strong
Graphene has lots of uses in …
electronics and composite materials (materials that have things added to make them more useful).
Graphene makes materials stronger without making them …
much heavier.
Graphene can be used in
solar panels, batteries
a single layer of graphite is called …
graphene
Fullerenes are …
molecules of carbon atoms that take up hollow structures.
what are molecules of carbon atoms that take up hollow structures?
Fullerenes
Fullerenes’ structure is usually carbon atoms arranged in ——, but …
hexagonal (6-sided) rings
pentagonal (5-sided) and heptagonal (7-sided) carbon rings can also be found
—— was the first fullerene that was discovered
Buckminsterfullerene
Generally speaking, —– fullerenes come in a wide range of size
spherical
Generally speaking, spherical fullerenes come in a …
wide range of sizes
fullerenes common uses include:
(3)
Catalysts.
Lubricants.
As vehicles for transporting drugs into our bodies
Carbon nanotubes are …
fullerenes that take the shape of a cylinder.
Carbon nanotubes are often called —– because …
molecular wires
they have a tiny diameter but can be incredibly long.
Because of the —– covalent bonds between carbon atoms, nanotubes are…
- strong
- exceptionally strong for their size.
The strength and electrical conductivity of nanotubes make them useful for:
In electronics.
In nanotechnology.
For strengthening materials (e.g. tennis racket frames).
Spherical fullerenes are perfect for delivering drugs as they …
can trap molecules inside themselves.
what the main 4 allotropes of carbon
fullerenes
diamond
graphite
graphene
nanoparticles are _________nm long
1-100
nanoparticles are __________ atoms long
10-1000
Fine particles are _________ nm long
100-2500
Fine particles are _________ atoms long
1000-25000
coarse particles are ________nm long
2500-10000
coarse particles are ________ atoms long
25000-100000
name the three types of ‘clumps’ of particles
fine particles
nanoparticles
coarse particles
what is another name for coarse particles
dust
nanoparticles are —– than individual atoms but …
larger
too small to be seen with the human eye.
The surface area to volume ratio of nanoparticles is
high.
The surface area to volume ratio of nanoparticles is high.
This means that …
smaller amounts of materials can be used for our desired purpose (e.g. as catalysts or in sun cream) compared to using normal sized particles and still produce the same affect.This makes them cheaper and more efficient to use than larger particles.
As nanoscience is still a very new area of research, there are still possible disadvantages of nanoparticles that
we do not know about.
we don’t know the long-term effect of nanoparticles …
on the environment or on human health
As particles get smaller, their surface area to volume ratio…
increases
decreasing the length of a cube’s side by a factor of 100 —– its surface area to volume ratio by a factor of 100.
increases
due to particles get smaller, their surface area to volume ratio increases, —- amounts of nanoparticles to be used for a desired purpose compared to using normal-sized particles.
This means that …
- smaller
- they are cheaper and more efficient to use.
Using nanoparticles can also — the properties of the material completely.
change
‘normal’ gold particles are extremely unreactive, but gold nanoparticles …
can be very efficient catalysts for many processes
A normal-sized gold particle is unreactive. What could I do to use gold as a catalyst?
Decreasing the size of the particle to nanoparticle size transforms the gold particles into incredibly efficient catalysts due to a massive increase to their surface area to volume ratio
The very high surface area of nanoparticles means that …
there is a larger surface on which reactions can be catalysed (sped up).
Fullerene nanoparticles can be used to
efficiently deliver drugs to a specific area of the body to target a disease.
Carbon nanotubes are used in new computer chips because …
of their good electrical conductivity.
Nanoparticles are so small that …
Eg …
- visible light passes through them, making them transparent.
- white substances, like sun cream, can be made transparent by using nanoparticles.
Nanoparticles can have a___________
p_______
These nanoparticles can be used to …
- antimicrobial properties.
- make deodorants more effective by killing bacteria that generate bad smells.
state 5 uses of nanoparticles
- electronics
- cosmetics
- deodorants
- catalysts
- medicine
state the 3 types of bonding
ionic
covalent
metallic
What is an ionic bond formed from?
an attraction between oppositely charged IONS
What forces hold together an ionic lattice?
electrostatic forces
What is the empirical formula of C7H4O2
C7H4O2
what is a empirical formula?
The simplest whole number ratio of atoms of each element in a compound
What type of bonding involves the movement of electrons from one atom to another?
ionic bonding
Why are polymers often solid at room temperature but melt easily?
- inter-molecular forces are still weaker than chemical bonds
- their size means they have many inter-molecular interations
what are Intermolecular forces?
forces that act between molecules
Intermolecular forces are also called
inter-molecular interations
simple covalent molecules are held together by —– intermolecular forces
weak
what does delocalised electron mean
the electron is free to move throughout the structure and conduct
electricity and thermal energy.
Graphite is formed of ——— atoms. These are not held together by
1 but rather by 2.
layers of carbon
1.covalent bonds
2.intermolecular forces
the layers IN GRAPHITE can easily slide over each other making the compound …
slippery
What is the charge on a carbonate ion?
2-
Carbonate Ion is a …
NEGATIVE polyatomic ion with formula of CO3(2-)
How many double bonds and single bonds are there in a carbonate ion?
number of single bonds =2
number of double bonds=1
Graphite exists in a —– covalent structure.
giant
Which feature of graphite’s structure makes it a good electrical conductor?
1 electron from every carbon atom is delocalised
