C3-Structure and Bonding Flashcards
What are the three common states of matter ?
Solid , liquid , gas .
One fact about solids .
-Solids are extremely hard to compress (squeeze) , as particles in a solid are packed togteher in a regular pattern , with almost no spaces between the particles .
Another fact about soilds .
Solids have a fixed shpe and cannot flow from place to place ..
-Solid particles can virbate but can’t move place to place .
One fact about Liquids .
-Liquids are extremly hard to cpmress - as particles are close togetehr with not many spaces between them .
Another fact about Liquids .
-Unlike soilds , liquids tkae the shpe of their container , they flow from place to place , as particles in a liquid can mvoe .
Fact about gases .
-Gases are extremely easy to compress . As particles in gases are widely spaced .
-Gases spread out and fill the space of their container , As particles in a gas move quickkly and randomly .
How can we change the state of a substance ?
By puttign in or taking out energy .
How do we change a solid to a liquid .
Called melting , takes place at meltign point .
-Particles in a liquid moving , so hae more inetic energy than particles in a solid .
-Means have to put energy to convert solid to liquid , energy needed to break down forces of atraction between partciles in solid , ater broken , forces can move .
The stornger the ofrces of attraction between the particles …
The more energy we have to put in to break them and the higher the melting points .
Wax candle - low melting point s forces of attraction weak between particles easy to break .
-sodiumc hlrid e, storng ofrces of attraction between particles so high melting point .
Liquid to solid
freezing temperature at melting point .
Liquid to gas .
-Boiling point
-Stronger forces of atrraction between particles means boiling point high , as it takes a lot of enegry to break down forces to boil the liquid .
Gas to liquid condensing , the temperature for this is boiling point .
What is one limitation of the particle model ?
-Assumes all the particles are soild spheres , not true as the particles have lots of different shapes are not solid .
What is another limitation of the particle mdoel ?
Simple particle model assumes there are no forces between particle s, this is not the cses , forces have a major impact on melting and boiling point of a substance .
Whyd o elements react ?
-To gain an a full outer shell
-When a metal reacts with a non metal its called IONIC BONDING .
Do some ionic bonding questions .
:))
Check sheet ,
Describe what is happening in this reaction (4)
-One electron
-Passes from the sodium atom
-To Chlorine atom
-Both atoms achieve a full outer energy level .
What do ionic compounds form ?
The form giant structures (giant ionic lattices )
-Where a positive ion i surrounded in a negative ion .
More about giant ionic lattice’s
-They are 3 Dimensional
-Have very strong electrosatic forces of attraction , between positive and negative ions , holding them in place , and can act in all direction s.
What is one key property of ionic compounds >
-They have very high melting and boiling points , as thr strong electrostatic forces requrie a great deal of energy to break .
What is another kery property of ionic compounds ?
Ionic compounds cannot conduct electricity when theya re soilkds , as the ions can’t move , they are locked in place by the strong electrostaic forces of attraction .
Whenc an ionic compounds conduct electricity ?
-When they are melted or dissolved in water , as the ions can now move and carry the charge NOT ELECTRONS .
Practice some Covalent bonding questions .
-work out how manhy electrons outer shell UNLIKE IONIC.
-thuink how many each element needs for full outer shell
:))
What are the boiling points of small covalent moelcules ?
-Small covalnet molecules have a low melting and boiling point .
-Menaing they are are usually gases or liquids at room temperature .
Why do small covalent bonds have low melting and boiling points .
-As threy have weak intermolecualr forces bettween the molecule to another molecule , which odn’t require a lot of energy to brek .
Expalin porcess of breaking bonds in small covalnet sturctures .
-Atoms in each molecule held togther by strong covalne tbonds .
-but weak intermolecular forces , one movleucle to another , don;t requrie a lot of nergy to break .
-Increas the temperature anf the vibrations increase , at a point , vibrations strong enough to break the waeak intermolecular forces holding mollecules togther - turn into a gas .
As we increase the size of the covlent molecules …
intermolecular forces increase .
Why don’t small covalnet molecules no conduct electriciy ?
As the molecules do not have an overall electric charge .
State of giant covalent moelcules at room tempeature ?
Giant covalent molecules are always solid at room temperature .
As giant covalent molecules have millions of strong covalent bonds .
-Menaing they have high melting and boiling ponts . /
Example of a giant covalentmolecule .
Diamond is a form of the elemnt carbon .
-Each carbon atom forms four strong covalnet bonds to four other carbon atoms .
-Diamond have a huge number of covalent bonds , these hae o be broken when diamond melted ,reequiring a great dela of energy .
Melting point 3700 degrees .
Why can’t diamond conduct electricity ?
As there are no free elctrons to carry elecrical charge .
Another covalent molecule ?
Silicon Dioxide (Silica /Sand ) .
-Silicion dioixide has a very high melting and oiling point .
-As the number of strong covalent bonds mus e broken , this takes a great deal of energy .
Give a few propertie of graphite .
-Has a high metlign and boilign point .
-Is soft and slippery .
-escvellent conductor of both electricty and heat .
Structure of graphite .
-Grpahite formed from the elemnt Carbon . Each carbona toms froms three covalent bonds .
-Carbon atoms from heaxagonal rings .
Why does graphite have a high mp and bp ?
-As graphite has many strong covalent bonds , takes a great deal of energy to break these , so graphite has a high mp and bp .
Why is graphite slippery ?
-The hexagonal rings are in layers . NO covalent bonds betwen layes so can slide , making graphite slippery .
Why can graphite conduct electricity ?
Carboon froms three bonds , single elctron on outer shell that isn’‘t ina covalent bond .
-These are delocalised electrons meanin they can move and conduct therml energy and electircity .
is graphite a metal ?
NO , graphite is based on the elemtn carbon and not a metal .
-Grpahite is similar to metals as both ar good condcutors of heat and electricity , as both have delocalised electrons that can move .
What is graphene ?
Grpahene is a single layer of graphite .
-Graphene is one atom thick .
Propertieis of graphene .
-Excellent conductors of electricity as it has delocalised electrons .
-Graphene is extremely strong .
What are fullerenes ?
-Fullernes are moelcules of crbon stoms with hollow shapes .
-Usually fullerenes have hexagnoal rings of carbona toms but also or 7 rings of carbon toms .
What is te first fullerene discoevred ?
Buckminster Fullerne , ahs 60 carbon atoms - carbon atoms form rings orf 5 or 6 carbons .
What are some uses of Fullerenes .
-Pharmacueticla delivery into bodiey .
-Lubricant
-Catalysts .
What are Carbon nano tubes .
Fullernes hsaped into long cylidners .
What are two properites of carbon nano tubes .
-High tensile strength (strech without breaking )
-Excellent conductors of hea and electricty and used to reinforce metals like tennis rackets .
Structure of metals .
Metals consitis of a giant structrue of atoms arranged regularly
- electrons in the outer energy leevel of each atom is delocalised
structure of metals .
Strong electrostatic attracting between the sea of delocalsied negative electros and positive ions .
the electrostatic attracts in metla sare the metalic bonds - which are strong .
Properties of meals .
Metals have high metling and boiling points ,a s a great deal of energy is required to break the strong metallic bonds .
Why are metals good conductors of hear and electricity .
-As the sea of delcoalised electrons can mov e, and as electrons are charged , means electrons can carry electric current and thermal energy allowign the them to conduct heat .
Why can metals be bent and hsaped ?
As in metals , layers of atoms are able to slie over eachother . due to deloaclised electron allowing layers to distort a little .
PROBLEM - some pure metals aren’t hard enough to be useufl (copper and gold)
SO HAVE TO MAKE AN ALLOY . to make them harder .
What is an alloy , and how is is stronger than a pure metal ?
An alloy is a mixture of metals .
-The different sizes of the atoms , distorts hte layers , making it more difficult for them to slide over eachtoehr . Hence why allys harder than pure metals .
What are nano particles .
Have a diameter of 1-100 nanometres , onlyc ontain a few hundred atoms .
-As the particle size decreasesby ten times , the surface area to volume ratioio increasees byt en times .
do surface area/volume
Nano particles have a huge surace area to volume ratio :
Small amount of nanoparticles have massive surface aea .
-Much smaller quanitty of nano particles compaered tonano particle s.
Ues of nanoparticles .
cosemtic , sunscreen ,catlayast
RISK
-nanoparticles going into surroundings can damage the lungs when breathing in tinny particles as it possible for them to be absorbed into body and cells adn can enter blood stream . possibly .
problems with dot and cross diagrams
-dosent shwo the strucutre of compoud
-the size of the ions
-or how the ions are arranged
