Atoms Elements & Compounds

What they are..

proton neutrons mass number and atomic...

arrangenment of atoms...

forming bonds... covalent and ionic

Periodic table

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  • Created by: darcy
  • Created on: 21-11-11 12:14

AQA 1.1 Atoms

Atoms consist of NEUCLEUS [containg  PROTONS and NEUTRONS] and ELECTRONS orbit around the neucleus in shells - there are 2 atoms in the first shell then up to 8 in the consetutive shells.

When Atoms combine they are called COMPOUNDS.

Atoms all have symbols they are arranged in the periodic table E.G clacium is Ca.

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AQA 1.2 Protons neutron and electrons

      ATOMIC NUMBER - Number of prtons in an atom

      MASS NUMBER - The number of protons + Neutrons  (summerized as below)

                 Mass      Charge                        

Protons        1              +1                                Mass Number (20)

Neutrons      1               0                                                       Symbol  (Ca)

Electrons      1              -1                                Atomic number (40.078)

To find the number of neutrons do = MASS NUMBER - ATOMIC NUMBER

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AQA 1.3 Arrangment Of Electrons (Card 1)

ELECTRONS fill up SHELLS - The first SHELL can accomedate 2 ELECTRONS                        - The second and consectutive shells can accomidate up to 8 electrons. (below  the first few elements)

Element        Sybol   Atomic Number    electronic arrangement

Hydrogen       H                   1                              1

Hellium            He                2                              2

Lithium            Li                 3                              2,1

Beryllium        Be                 4                              2,2

Boron             B                   5                              2,3

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AQA 1.3 Arrangment Of Electrons (Card 2)

ELEMENTS with atoms that have the same number of ELECTRONS in the outer shell belong in the same group of the periodic table.E.G. Group 1 - Alkali Metals

Lithium  Li  2,1

Sodium  Na 2, 8, 1

Potassium  K  2, 8, 8, 1

And ELEMENTS in the same group all have similar properti

ELEMENTS in group 8 or 0 are called NOBLE GASES they all have full outer shells are are the most stable elements

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AQA 1.4 forming bonds (card 1)

BONDS can be joined by TRANSFER of ELECTRONS which lead to formation of IONS (positive ions CATIONS     Negative ions ANIONS) E.G

7                        Has electronic arrangementsof 2,1                                                 

    Li

3

19                    Has electronic arrangement of 2,7

     F

9

Both want full outer shells so Li transfers it's outer electron to F (florine)

7      +       19      -

  Li                   F

3                 9

(2)               (2, 8)

 

Li now has one more proton than electron therefore posotive

F now has one less electron than proton therefore negative

BONDS can also be joined by SHARING electrons this leads to COVALENT bonds- in such cases ions are not formed instead MOLECULES are formed.

 

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AQA 1.5 EQUATIONS

REACTENTS ---> Products

A) Write a word equations

Hydroden + Oxygen ---> Water

B) Write a symbol equation

H2 (g)  +  O2 (g) ---> H20 (l)   (g) gass  (s) solid  (l)liquid (aq) Aqueous solution

C) Balance the above equation

2H2 (g) + O2 (g) ---> 2H20 (l)   (On the left of the quation there are 4 H and 2O)

(on the right there are 4 H and 2 O)

nb. Atoms cannot be created or destryed in a chemical reaction therefore total mass of reactants = products

2 little 2

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