Chemistry

Revision for Structures exam 

 

HideShow resource information

Atomic Structure:

             Atomic mass = total protons & neutrons 

             Atomic Number = No of Protons 

             Proton Number = No of Electrons 

 

                                  Period No = No of Shells 

                                  Group No = No of e- in outer shell 

 

Metal form compounds by loosing E`s, the larger the metal atom, the more easily the E. 

 

 

1 of 20

Bonding

Metal + Metal = Metallic Bonding

Metal + Non Metal = Ionic Bonding 

Non Metal + Non Metal = Covalent Bonding 

 

Ionic Bond - Is the strong attraction between oppositely charged ions.

Metal Bond - All metal atoms lose their outer electrons and become positive ions

Covalent Bond - Between 2 non metal atoms involving sharing electrons  

 

Metals always form Positive Ions  (Cations attracted to the cathode) 

Non Metals  always form negative ions ( Anions attracted to the anode)

2 of 20

Electrolysis

To conduct electricity we need charged particals ( electons and ions) which are free to move 

Positive ions move to the negative electrode, gaining a number of electrons 

negative ions move to the posstive electrode, loosing a number of electons 

The metal ions are arrange in a giant lattice, surrounded  by a sea of electrons

simple covalent compounds have low melting points because the force between the particles is weak and only needs a small amount of energy to separate them  

 

3 of 20

Crude Oils

Pertrol 

Naptha

Kerosene

Diesel 

Oils 

Bitumein + wax 

4 of 20

Cracking

Cracking involves the breaking down of long chain hydrocarbons into more usefull shot chain hydrocarbons which release energy more qucikly when burned. 

Alkane are saturated hydrocarbons containing only one single bond                          

CnH2n+ 2

Alkenes are unsaturated hydrocarbons contains at least one double bond

CnH2n

Cracking producses 3 mollecules of ethene and one other product.

5 of 20

Alkenes

Test for alkenes 

Bromine water is decolourised by alkenes ( Orange to colorless)

Polymer - Very long chains of hydrocarbons, used as plactics made by linking  lots of alkene molucules together 

addition polymers - made from alkenes - Thermosetting & Thermoplastic 

Thermosetting - Rigid, reatins shape can not be re- molded  or re-shaped 

Thermoplastic - can be melted and then re molded into a different shape.

 

 

 

6 of 20

Collision Theory

For any reaction to occur, particles must collide. the particles must have sufficient energy - activation energy 

 

anythink that:

1) cause more collisions  

2) increases energy of particles 

3) reduces activity energy 

will speed up the rate of reaction 

Particles have move energy causing the particles to cover a wide surface area in the same time more likely to cause collisions 

7 of 20

Catalyst

catalyst is something that speeds up the rate of reaction or takes part in the process to create a faster solution without being used up 

e.g Yeast for alcohol, magnesium ox-side for aluminum

catalyst are extremely important in industry e.g catalyst in cars. 

 

the smaller the particle size, results in a bigger surface area as it is also equivalent  of mass meaning move collisions and faster reactions 

8 of 20

Relative Molecular Mass

RMM = sum of atomic masses of all atoms in a compound 

H20 = 2xH (2x1) + 1xO (1x16) = 18 

% element in a compound 

Atomic Mass of Elements x No of Atoms             X 100 

Molecular Mass of Compound

 

 

 

9 of 20

Relative Molecular Mass

% of Atom Economy - Higher Yield Less Waste, Lower Yield More Waste 

Mass or Usefull Product     X100

Total Mass of all Products 

 

10 of 20

Reacting Masses

How Much Magnesium will react with 50G of Oxygen 

 

 

 

What mass of sulfur is need to make 500g of H2S4

11 of 20

% of Yield

mass of product x 100 

maximum possible mass 

 

100g of magnesium product produced 116g of mgo what is the % yield 

 

 

264g of silver chloride was orbtained from the reaction of magnesium chloride and silver nitrate (ag=108 cl = 35.5) 

 

 

 

 

12 of 20

Empirical Formula

Simplest Ratio Of atoms in a molecule 

eg ethene has formulas c2h4 emprical = c2 

c3h8 emprical = same 

c6h14 emprical = c3h7

a compound of carbon and oxygen contains 0.30g c and 0.80G of o

 

 

 

 

13 of 20

Emprical Formulma

A compound contains 20% magnesium 26.1% sulfur and rest = oxygen 

find the emprical formula 

 

 

14 of 20

Equilibrium

Equilibrium - the rate of the forwards and backwards reactions is the same 

in a system at eqilibrium the postion of equilibrium will move to oppose changles to the conditions 

 

 

 

15 of 20

Harber Process

16 of 20

Endo & Exo

Bond Breaking is Endothemric 

Brond Making is Exothermic 

the reaction is extothermic beacuse there is a stronger bong causing more energy creating more heat 

 

endothermic beaxcuse it takes move energy  needed to break a bond. 

 

 

17 of 20

fertilisers

Fertilsers 

mainly contain nitrogen; phosphorus aqnd potassium 

advatages-        no need for crop rotations

                          Larger Crops 

                          More effective use 

Disadvatges -    soluable 

                          eutrophication 

18 of 20

cracking diagram

19 of 20

Force Between Particels

melting points depends on how strongly particles are attracted to each other. melting required particles to be free to move - i.e overcomes forces of attraction 

electrons & ions must be free for any atom to conduct electricity 

chemical bonds are strong - covalent , ionic, metallic

 

20 of 20

Comments

No comments have yet been made

Similar Science resources:

See all Science resources »See all Chemistry resources »