Bonding

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  • Created by: samya_
  • Created on: 04-01-18 12:18
What is ionic bonding
When ions are held together by electrostatic attraction
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How to work out formula of an ionic compound
Look at charges as the overall charge of any compound is zerom
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What type of structure does sodium chloride have
Giant ionic lattice structure
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What is. A lattice and why is the structure called "giant"
Lattice is just a regular structure and it is called giant because its made up of the same basic unit repeated over and over again. Nacl has cubic shape
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What does the structure of an ionic compound determine
Their physical properties
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3 properties of ionic compounds EXPLAIN
1) conduct electricity when molten or dissolved NOT solid. Ions in liquids free to move and carry charge in solid ions are in fixed positions by strong ionic bonds 2) high melting points, strong electrostatic lots of energy to overcome
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CONTINUED???
3) dissolve in water. Water molecules are polar meg and positive charged parts. These charged parts pull ions away from the lattice causing it to dissolve
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what is covalent bonding
When atoms share electrons with one another so they've all got full outer shells FORM MOLECUKES
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Whenwhat do giant covalent structures have
Huge network of covalently bonded atoms MACROMOELCUKAR STRUCTRUE carbon atoms can form this type of structure becasue they can each form 4 strong covalent bonds . GRAPHITE DIAMOND
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What is graphite
Sheets of hexagons with delocalised electrons
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Explain structure of graphite
Weak bonds between layers easily broken , so sheets can slide over each other- slipppery- used as dry lubricant in pencils * delocalised electrons aren't attached to particular carbons atoms so free to move and carry charge, so is electrical conduct
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CONTINUES
* layers quite far alarm compared to length of covalent bonds, so has low density, used to make strong light weigh sports equip * high melting due strong cov bonds sublimes at over 3900K *insoluble in any solvent as cov bonds in sheets v strong
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What does sublime mean
To change straight from a solid to a gas
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Explain structure of diamond
Each carbon atoms forms four covalent bonds in a very rigid structure . This makes diamond very hard ATOMS ARRANGE THEMSELVES IN TETRAHEDRAL SHAPE
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What is dative covalent bonding?
Where both electrons come from one atom E.G. AMMONIUM ION (NH4+ ) shown by arrow pointing away from donor atom ->
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Factors of diamond due to string covalent bonds
Very high melting point, very hard used in diamond tip drills and saw * vibrations travel easy thrkught stiff lattice so good thermal conductor *cant conduct electricity * insoluble in any solvent *structure make sit refract light a lot, so sparkles
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What is eldtronegativity
Atoms ability to attract the electron pair in covalnt bond
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What happens In a polar bond
In a polar bond, the difference in electronegativiry between the two atoms causes a permanent dipole. A dipole is a difference in charge between two atoms caused by a shift in electron density in the bond GREAT DIFF IN ELECNEG TH EMORE POLAR THE BOND
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What are the 3 inetremolecuksr forces in order of strength
Hydrogen bonding, permanent dipole-dipole. Van dear waal s
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PolAr molecules have permanent dipole-dipole forces
Susbstanfe made up of molecules that have permanent dipoles there will be weak e,ctrostatic firces of attraction between the delta pos and delta neg charges on neighbouring molecules
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Explain van dear waal forces (induced dipole-dipole)
Electrons in charge clouds are always moving really quickly becasue electrons are CONSTANKY MOVING THE DIPOELS ARE BEING DESTROYED AND CERATED ALL THE TIME. even thought the dipoles keep changing the overall effect is for the atoms tk attract each ot
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What do can dear waal say forces hold
Moe,dukes in a lattice tiger ehr. STRONG COVAKENR BODNS HOLD THE IODINE ATOMS . BUT THE MOLECUEKS ARE THEN HELD TIEGTHER IN A MOLECULAR LATTICE ARRANGEMENT BY WEAK VAN DRER WAALS ATTRACTIONS
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When does hydrogen bonding only happen
When hydrogjenjs covalently bonded to fluorine nitrogen or oxygen
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Explain why fluorine nitrogen and oxygen
They are very electronegative so they draw bonding electrons away from the hydrogen atom. Bond is so polarised, and hydrogen has such a high charge density (since V small) that the hydrogen atoms forms weak bonds with the lone pair electrons in F,N
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Explain giant structure of metals
Delocalised electrons, positive metal ions attracted to negative free ions. Form a lattice in a sea of delocalised electrons. METALLIC BONDING
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Properties of metals due to metallic bonding
High melting point since strong eekctrostauc forces, , Number of free electrons per atom affects melting point, more means stronger bond so higher melting . Free electrons pass kinetic energy so good thermal, free carry current good electrical Insolu
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Why to simple covalent binds have relatively low melting and boiling points
To melt or boil them only need to overcome the intermolecular forces that hold the molecules tigetehr NOT COVAKENT BONDS
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Card 2

Front

How to work out formula of an ionic compound

Back

Look at charges as the overall charge of any compound is zerom

Card 3

Front

What type of structure does sodium chloride have

Back

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Card 4

Front

What is. A lattice and why is the structure called "giant"

Back

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Card 5

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What does the structure of an ionic compound determine

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