C3.1 - C3.12 Structure And Bonding✔️ Flashcards
What is convalent bonding?
When non-metals share electrons - strong bonds between the atoms
What is ionic bonding?
Transferring of electrons - atoms involved loose or gain electrons form charged particles called ions
What are Ionic compounds?
Giant structure of ions arranged in a lattice with strong electrostatic forces of attraction acting in all directions
Why do Ionic lattices have high melting and boiling points?
lots of energy to break giant ionic lattice because strong ionic bonds and electrostatic forces of attraction in all directions
When can ionic compounds conduct electricity?
molten or dissolved in water
What are giant convalent structures?
Giant structure where huge number of atoms held together by network of convalent bonds sometimes refered to as macromolecules example is diamond
Explain 3 features of convalent bonding?
1)atoms held tightly - very strong
2)forces of attraction between indivisual molecules relativley small - not much energy to overcome
3)intermolecular forces increase with size of molecule - larger molecules have higher melting and boiling points
Why can’t compounds made of simple molecules conduct electric when molten or dissolved in water?
Because there is no overall charge on simple molecules so they cant carry electrical charges have to be molten or dissolved in water.
What are giant convalent structure?
Huge number of atoms held together by stong convalent bonds for example diamond and graphite.
Three properties of giant convalent structure?
-high melting and boiling points
-insoluble in water
-apart from graphite - are hard and do not conduct electric
Explain the bonding in graphite?
carbon atoms only bonded to three other carbon atoms by convalent bonds and they form hexagonal patterns of giant layers however there are weak intermolecular forces between layers (no convalent bonds) and they contain delocalised electrons.
Why is graphite slippery?
no convalent bond between layers - only weak intermolecular forces - layer can slide over each other this is why it is used as a lubricant
What are delocalised electrons?
electrons free and mobile to move along the layers of an ion/molecule/metal and allows the element to conduct electric and are also found in metalic bonding
Why can diamond not conduct electric?
atoms have no free electrons - outer shell electrons all involved in convalent bonding
Three Properties of graphite?
-excellent conductor of thermal energy
-conducts electric
-slippery therefore used as lubricant
What are fullerense?
hollow shaped molecules of carbon that form shapes like football balls and rugby balls
What are nanotubes?
Cylindrical fullerenes - very thin - length larger then diamteter
Two uses of Fullerene?
-drug delivery used as bucky mules
-lubricants and catalysts - large surface area to volume ratio
What is graphene?
An atom thick layer of interlocking hexagonal rings of carbon atoms used for making computer chips
Three Properties of graphene?
-Excellent conductor of thermal energy and electrictiy
-low density
-most reactive form of carbon
Describe arrangment of atoms in metals?
Atoms in metal are built up layer upon layer in a regular pattern an are packed tightly together
What are the properties of metalic bonding?
-outer electrons can easily move throughout structure
-outer electrons form a ‘sea’ of delocalised surrounding positivley charged metal ions
-strong electrostatic forces of attraction between negativley charged electrons and positivly charged ions
Explain the bonding in metal - refer to electrons and charges?
Strong electrostatic attraction between negativley charged electrons and positivley charged ions bond the metal ions to each other with delocalised electrons free to move throughout lattice
Define an alloy?
Alloys are mixtures of two or more elements (at least one of which is a metal) - harder then pure metals because it is harder for the layers to slide over each other as the atoms are different sizes
Properties of metals?
-high melting and boiling points
-good thermal and electrical conductors
-metals are shapeable
What is Nanoscience?
Study of small particles that are between 1 and 100 nanometeres in size
Why are nanoparticles more reactive than materials with normal size particles?
They have a high surface area to volume ratio which allows a large exposure of atoms at the surface of the nanoparticles
Uses of nanoparticles?
-coating glass
-suncreens - more effective at blocking suns UV rays
-cosmetic industry - deodrants/face creams ext - absorb deeper into the skin
-deliver dugs - nanocages carry cancer-fighting drugs
Risks of nanoparticles?
-large surface areas makes the reactive - could explode
-find there way into our lungs or blood streams
-damage the enviorment
properties of diamond?
The carbon atoms in diamond have a rigid giant convalent structure making it a very hard substance.Can not conduct electric as their is no delocalised elctrons
Why can metals be bent and shaped?
Because the layers of atoms (or positivley charged ions) in a giant metallic structure can slide over each other
Why are alloys stronger the metals?
Harder than pure metal because the regular layers in a pure metal are distorted by atoms of different sizes in an alloy
what is the particle theory based on?
Based on the fact all matter is made up of tiny particles and describes:
-the movment of the particles
-average distance bwteen the particle
How is energy transfered when a substance condenses or freezes?
Energy transferred from the substance to the surroundings
How is energy transfered when a substance melts or boils?
Energy transferrd from the surroundings to the substance
What are limitations of the particle model?
Assumes particles are made up of solid sphere with no forces operating between them - atoms are mostly empty space
Define compound?
Compound contains two or more elements which are chemicaly combined
Why can ionic compounds conduct electric when molten or dissolved in water?
The ions can become mobile and can carry charge through the liquid
Features of Ionic compouns?
-high melting and bioling points
-Lot of energy to break ionic bonds
Why is a lot of energy required to break up a giant ionic lattice?
Because there are strong electrostatic forces of attraction acting all directions that must be broken
What happens to the ions when a giant ionic lattice is broken?
Ions become mobile and can move around and are attracted to the oppositly charged electrodes therefore they can carry electrical charges through the liquid
How are convalent bonds formend?
When atoms of non-metals shair pairs of electrons with each other - each share pair is a convalent bond
Issues with the 2D ball and stick model?
Does not show the true shape of the molecule
What are polymers?
Made up of many small reactive molecules that bond to each other to form long chains
Why is graphite a good thermal conductor?
When more energy is transfered to the delocalised electrons they move around faster and rapidly transfer the energy along the layers in the graphite
Two features of nanotubes?
-high tensile strength - used to reinforce composite materials
-high electrical and thermal conductivity - have delocalised electrons
Why can metals be shaped and bent?
When struck the metal atoms can slip past one another without breaking up the metals structure
Explain why metals have high melting and boiling points?
Metals have a giant structure with electrostatic forces of attraction acting in all directions therefore a lot of energy needed to seperate metal ions from their fixed position
Explain why metals are good thermal/electrical conductors?
Their delocalised electrons can readily flow through the giant metallic lattice - electrical charge and thermal energy are transferred quickly through the metal by delocalised electrons
Value of 1 nanometre?
1 nm = 1 x 10 ^-9 m
How might nanoparticles help in chemical Industry?
May result in smaller quantities of materials such as catalysts being needed for industrial processes which will help with reducing costs
Why is glass coated with nanoparticles?
Sunshine triggers a chemical reaction that breaks down dirt that lands on the window and when it rains the water is spread out evenly over the surface of the glass washing of any dirt
Why are nanoparticles used in sun screan?
Provides a better covereage on the skin from the suns rays as the nanoparticles are absorbed better into the skin
Risks with nanoparticles?
-large explosion if there is a spark near a large quantity
-risk of them finding there way into enviorment
-health risks could damage the lungs
Future deelopments of nanoparticles?
Can be developed and used as highly sensetive sensors and used in the tech industry.also there is development and designing of suits which would be used by the army capable of withstanding bullets and sensors to provide medical data to a team.
What happens to metals in ionic compounds?
Tend to lose electrons
What happens to non metals in ionic bonding?
Tend to gain electrons
Explain ionic bonding in terms of electrons and charge?
Negativley charged electrons held/attracted to the positive nuceli
