Bonding ,Structure,Properties of matter Flashcards
What are ions
-charged particles
-they can be single atoms or groups of atoms
What do atoms have to do to become ions
-lose or gain electrons
Why do atoms want to become ions
-to get a full outer shell like a noble gas
- also known as ‘stable electronic structure’
What are atoms with a fully outer shell qualities
they are very stable
What happens when metals form ions
-they lose electrons from their outer shell to form positive ions
What happens when non metals form ions
-they gain electrons in their outer shell to form negative ions
How to find the charge of the ion
the number of electrons lost or gained is the same as the charge on the ion
eg. 2 e are lost so charge is 2+
Which are the elements that most readily form ions
those that are in groups
1,2,6,7
What are Group 1 and 2 + their process to be ions
-they are metals
-they lose electrons to form positive ions
What are positive ions called
cations
What are Group 6 and 7 + their process to be ions
-are non metals
-they gain electrons to form negative ions
What are negative ions called
anions
What do elements in the same group form and why
-they form ions with the same charges
-as those in the same group have the same number of outer electrons
What is Group 1’s charge
1+
What is Group 2’s ion charge
2+
What is Group 6’s ion charge
2-
What is Group 7’s ion charge
1-
Equation for sodium atom (group 1) becoming an ion
Na —> Na^+ + e^-
Equation for Magnesium atom (group 2) becoming an ion
Mg –> Mg ^2+ +2e^-
Equation for Chlorine atom (group 7) becoming an ion
Cl + e^- –> Cl^-
Equation for Oxygen atom(group 6) becoming an ion
O+ 2e^- –> O2-
So if the atom is gaining electrons ,where is the longer part of the equation
before the arrow
So if the atom is loosing electrons ,where is the longer part of the equation
After the arrow
What are the three types of ways particles bond to form compounds
-Ionic
-Covalent
-Metallic
What is reacting in ionic bonding
Metal and non metal reacting together
What happens to the metal and non metal in ionic bonding
-the metal atom loses electrons to form a positively charged atom
-the non metal gains these electrons to form a negatively charged ion
What is an ionic bond
-these oppositley charged ions are strongly attracted to one another by electrostatic forces
-this attraction is called an ionic bond
Which diagram shows how Ionic compounds are formed
Dot and Cross diagrams
What does a dot and cross diagram show
the arrangement of electrons in an atom or ion
Describe what happens in Magnesium Oxide
Describe what happens with magnesium chloride
Describe what happens with Sodium Oxide
Positives with dot and cross diagram
are useful for showing how ionic compounds are formed
Problems with dot and cross diagram
-don’t show the structure of the compound
-don’t show the size of the ions or how they’re arranged
Features of Ionic compounds
-have a structure called a giant ionic lattice
Describe the giant ionic lattice in ionic compounds
-the ions form a closely packed regular lattice arrangement
-there are very strong electrostatic forces of attraction between oppositely charged ions in all directions in the lattice
Example of a giant ionic lattice
A single crystal of sodium chloride
-Na+ and Cl- ions are held tg in a regular lattice
Describe 2 versions of a diagram of sodium chloride
What does the left 3d model of sodium chloride show…
-shows the relative sizes of the ions
-as well as the regular pattern of an ionic crystal
What does the left 3d model of sodium chloride NOT show…
-only lets you see the outer layer of the compound
What is the right model of sodium chloride
a ball and stick model
What does the right ball and stick model of sodium chloride show…
-shows the regular pattern of an ionic crystal
-shows how the ions are arranged
-also suggests that the crystal extends beyond what’s shown in the diagram
What does the right ball and stick model of sodium chloride NOT show…
-the model isn’t to scale so the relative sizes of the ions may not be shown
-in reality there aren’t gaps between ions
Properties of Ionic compounds (heating.)
-all have high melting points
-high boiling points
Why do ionic compounds have high melting and boiling points
-due to their many strong bonds between the ions
-it takes a lot of energy to overcome this attraction
What can ionic compounds not do as solids but can do as liquids, and why?
Solid:
ions are held in place, compounds can’t conduct electricity
Molten/melted :
the ions are free to move and they’ll carry electric charge
What can some ionic compounds do
-can dissolve in water
-this means the ions seperate and are all free to move in the solution
so they’ll carry electric charge
What is empirical formula
-formula of an ionic compound from a diagram of the compound
How to work out empirical formula of a dot and cross diagram
-count up how many atoms there are of each element
-write this down to get the emperical formula
How to work out empirical formula of a 3D diagram of the ionic lattice
-use it to work out what ions are in the ionic compound
-then you’ll have to balance the charges of the ions so that the overall charge of the compound is 0
What are covalent bonds
when NON METAL atoms bond together, they share pairs of electrons to make covalent bonds
Why are covalent bonds very strong
-the positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces
What do atoms only share for covalent bonds
only share electrons in their outer shells (highest energy levels)
What does covalent bonding happen with
-compounds of non metals
-non metal elements
Further expand on covalent bonds
-each single covalent bond provides one extra shared electron for each atom
-each atom generally makes enough covalent bonds to fill up its outer shell
What does covalent bonds give the non metals
a full outer shel
which gives them the electronic structure of a noble gas,which is very stable
What are the different ways to draw covalent bonds
-dot and cross diagram
-the displayed formula
-the 3D model
How to draw dot and cross diagram for covalent bonds
-electrons drawn in the overlap between the outer orbitals of 2 atoms are shared between those atoms
Why are dot a cross diagrams useful for covalent bonds
-showing which atoms the electrons in a covalent bond come from
What do covalent bonds dot and cross diagrams not show
-don’t show the relative sizes of the atoms or how the atoms are arranged in space
What is the displayed formula for covalent bonds
-shows the covalent bonds as single lines between atoms
pros of displayed formula for covalent bonds
-great way of showing how atoms are connected in large molecules
cons of displayed formula for covalent bonds
-don’t show the 3D structure of the molecule or which atoms the electrons in the covalent bond have come from
Pros of 3d model for covalent bonds
-shows the atoms, the covalent bonds and their arrangement in space next to eachother
Cons of 3d model for covalent bonds
-can quickly get confusing for large molecules where there are lots of atoms to include
-don’t show where the electrons in the bonds have come from either
How can u find the molecule formula for a simple molecular compounds
by counting up how many atoms of each element there are
What are simple molecular substances made up of
made up of molecules containing a few atoms joined together by covalent bonds
What do substances containing covalent bonds usually have
simple molecular structures
Describe the molecules in a simple molecular substance
-the atoms within the molecules are held together by very strong covalent bonds
-by contrast the forces of attraction between these molecules are v weak
Is it difficult to melt or boil a simple molecular compound ?
no as u only need to break these feeble intermolecular forces and NOT the covalent bonds
-so the melting and boiling points are very low as the molecules are easily parted from eachother
What are most molecular substances at room temp
-are gases or liquids
As molecules get bigger what happens?
-the strength of the intermolecular forces increases so more energy is needed to break them
-the melting and boiling points increase
Do molecular compounds conduct electricity and why?
NO they dont simply bcs they aren’t charged so there are no free electrons or ions
What are in Polymers and giant covalent structures
Covalent bonds
What is in a polymer
lots of small units are linked together to form a long molecule that has repeating sections
-all the atoms in a polymer are joined by strong covalent bonds
How to draw out a long polymer molecule
can draw the shortest repeating section called the repeating unit
-put n in the bottom corner to show the number of repeats
What do the polymer repeated units look like
How to find the molecular formula of a polymer
-write the molecular formula of the repeating unit in brackets
-put an n outside
-like the image before
So whats the molecular formula for polyethene from that image
(C2 H4) n
What is the state of most polymers at room temp
Solid
Why are polymers usually solid at room temp
-the intermolecular forces between polymer molecules are larger than between simple covalent molecules
-so more energy is needed to break them
Compare polymer’s boiling point with ionic or giant molecular compounds
-generally have lower boiling points that ionic or giant molecular compounds
-as their intermolecular forces are still weaker than ionic or covalent bonds
In giant covalent structures how are the atoms bonded
bonded to eachother by strong covalent bonds
Giant covalent structures melting+boiling point and why
Have very high melting and boiling points
-as lots of energy is needed to break the covalent bonds between atoms
When do giant covalent structures conduct energy
-they don’t as they don’t contain charged particles
-don’t conduct even when molten
-exception is Graphite
Describe Diamond structure
-each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure
Describe Graphite
-each carbon atom forms 3 covalent bonds to create layers of hexagons
-each carbon atom also has one delocalised electron
Describe Silicon dioxide
-sometimes called sillica
-is what sand is made up of
-each grain of sand is one giant structure of sillicon and oxygen
Show me what diamond looks like
Show me what graphite looks like
Show me what silicon dioxide looks like
What are allotropes
are different structural forms of the same element in the same physical state
Qualities of diamonds
-really hard
-very high melting point
-doesn’t conduct electricity
What are diamonds really hard
-as has a giant covalent structure
-made up of carbon atoms that each form 4 covalent bonds
Why do diamonds have a very high melting point
-their strong covalent bonds take a lot of energy to break
Why don’t diamonds conduct electricity
-because it has no free electrons or ions
What does graphite contain
each carbon atom only forms 3 covalent bonds creating sheets of carbon atoms arranged in hexagons
Qualities of graphite
-soft and slippery
-high melting point
-conducts electricity and thermal energy
Why is graphite soft and slippery (making an ideal lubricating material)
-aren’t any covalent bonds between the layers
-so they’re only held together weakly so free to move over eachother
Why does Graphite have a high melting point
-the covalent bonds in the layers need loads of energy to break
Why can Graphite conduct electricity and thermal energy
-only 3/4 carbon’s outer electrons are used in bonds so each carbon atom has one delocalised electron and can move
What is Graphene
-a sheet of carbon atoms joined together in hexagons
(one layer of graphite)
What dimensions is Graphene
-the sheet is just one atom think making it a two dimensional substance
Qualities of Graphene
-strong
-incredibly light
-can conduct electricity
Why is Graphene strong
the network of covalent bonds makes it very strong
Expand on Graphene being light
-due to being one atom thick
-so can be added to composite materials to improve their strength without adding much weight
Why can Graphene conduct electricity
-contains delocalised electrons so can conduct elec through the whole structure
-has potential to be used in electronics
What are Fullerenes
-are molecules of carbon
-shaped like closed tubes or hollow balls
What was the first fullerene to be discovered and its features
Buckminsterfullerene
-forms a hollow sphere
-molecular formula C60 (60 is below)
What are Fullerenes mainly made up of
-carbon atoms arranged in hexagons
-can also contain pentagons(rings of 5 carbon atoms) or heptagons (rings of 7 carbon atoms)
Uses of Fullerenes (medical)
-can be formed around another atom or molecule,then trapped
-this could be used to deliver a drug into the body
What does Fullrenes huge surface area allow then to be used for ….
-cld help to make great industrial catalysts
-induvidual catalyst molecules could be attached to the fullrenes
A third use of fullrenes
could also be great lubricants
overall what are the 3 uses of fullerenes
-deliver a drug into the body
-make catalysts
-great lubricants
What can fullerenes form
nanotubes- tiny carbon cylinders
Nano tube features
-ratio betweeen the length and diameter is very high
-can conduct electricity and thermal energy
-have high tensile strength
What is tensile strength
they don’t break when they are stretched
What is technology that uses very small particles like nanotubes
nanotechnology
Uses of nanotubes
-can be used in electronics
-to strengthen materials w/o adding much weight (eg tennis racket frames)
What do metals consist of
a giant structure
-held together by metallic bonding (very strong)
Describe the attractions in metals
-the electrons in the outer shell of the metal atoms are delocalised
-there are strong forces of electrostatic attraction between the positive metal ions and shared negative electrons
What do these forces of attraction in metals do
-hold the atoms together in a regular strucutre and are known as metallic bonding
Other substances held by metallic bonding
metallic elements and alloys
What essentially produce all the properties of metals
the delocalised electrons in the metallic bonds
Qualities of metals
-solid at room temp
-high melting+boiling points
-good conducters of heat and electricity
-most are malleable
Why do metals have very high melting and boiling points (solid at room temp)
-the electrostatic forces between the metal atoms and the delocalised electrons are very strong so need lots of energy to be broken
Why are metals good conducters of electricity and heat
-the delocalised electrons carry electrical charge and thermal energy through the whole structure
Why are most metals malleable
-the layers of atoms in a metal can slide over eachother (all same size)
-so can be bent or hammered or rolled into flat sheets
Problems with pure metals
-often too soft for certain jobs
What are alloys
a mixture of two or more metals
What is harder alloys or pure metals
alloys
Why are alloys harder
-have a mixture of dif elements with dif sixed atoms
-so the layers between the dif metal atoms are distorted
-making it difficult for them to slide over eachother
What are the 3 states of matter
-solids
-liquids
-gases
What does the state of something depend on
how strong the forces of attraction are between the particles of the material
What does the strength of the forces depend on (3)
- the material (structure of the substance + particles bonds)
- the temperature
- the pressure
Describe the forces of attraction in solids
-there are very strong forces of attraction between particles
-this holds them close tg in fixed positions to form a very regular lattice arrangement
Movement of particles in a solid
-don’t move from their position, keep a definite shape and volume
-don’t flow like liquids
-particles vibrate about their postions
What happens to particles in a solid when heated
-the hotter the solid becomes the more they vibrate
-causing solids to expand slightly when heated
Describe the forces of attraction in liquids
-weak force of attraction between the particles
so they are randomly arranged and free to move past eachother,tend to stick closely tg
Movement in particles in a liquid
-have a definite volume but not a definite shape, will flow to bottom of a container
-particles are constantly moving with random motion
What happens to particles in a liquid when heated
hotter the liquid gets the faster they move
-causes liquids to expand slightly when heated
Describe the forces of attraction in gases
-the force of attraction between particles is very weak
-so they are free to move and far apart
-particles travel in straight lines
Movement in particles in a gas
-gases don’t keep a definite shape or volume and will ifll any container
-particles move constantly with random motion
What happens to particles in a gas when heated
-the hotter the gas gets the faster they move
-gases either expand when heated or their pressure increases
What is particle theory
-easier to explain how the particles in a material behave
-shows each of the three states of matter by each particle as a small solid inelastic sphere
CONS of particle theory
-in reality particles aren’t solid or inelastic and are not spheres, they are atoms,ions or molecules
-model doesn’t show forces between particles so no way of knowing their strength
How are the different states shown with symbols
Solid = (s)
Liquid = (l)
gas = (g)
aqueous= (aq)
What does aqueous mean
means dissolved in water
What do physical changes do
-don’t change the particles just their arrangement or their energy
What is the process of solid to liquid and back
solid- liquid = melting
liquid - solid= freezing
What is the process of liquid to gas and back
liquid –> gas= boiling
gas–> liquid = condensing
What happens when a solid is heated
-the particles gain more energy
-makes them vibrate more, which weakens the forces that hold the solid together
What happens to particles at their melting point
-the particles have enough energy to break free from their positions
-turns into a liquid
What happens when a liquid is heated
-the particles gain even more energy
-energy makes the particles move faster
-which weakens and breaks the bonds holding the liquid together
What happens at the liquid’s boiling point
the particles have enough energy to break their bonds
-so boil / evaporate and becomes a gas
What happens as a gas cools
-the particles no longer have enough energy to overcome the forces of attraction between them
-bonds form between particles
What happens at the Condensing at the boiling point of the gas
-so many bonds have formed between the gas particles that the gas becomes a liquid
What happens when a liquid cools
-the particles have less energy so move around less
-not enough energy to overcome the attraction between the particles
-so more bonds form between them
What happens at the Freezing of the liquid at the melting point
-so many bonds have formed between particles that they are held in place
-the liquid becomes a solid
What does the amount of energy required for a substance to change state depend on
-how strong the forces between particles are
-the stronger the forces the more energy is needed to break them, and so the higher the melting and boiling points of the substance
