Friday, November 6, 2009

Structure of Atom


1        Table 1 shows the incomplete information about 3 atoms; X, Y and Z.
Atom
Proton number
Number of neutron
Number of electron
X

8
6
Y
6
6

Z
17

17

                                                                  Table 1
(a)                    State the name of subatomic particles that are found in nucleus of an atom.

……………………………………………………………………………………………  [1 mark]

(b)                    (i)         What is the term of the total number of protons and neutrons in an atom?

            …………………………………………………………………………………… [1 mark]

(ii)               The total number of protons and neutrons for atom Z is 35.
What is the number of neutron in atom Z?

……………………………………………………………………………………  [1 mark]

(iii)       Write the symbol for atom Z in the form of    A   X.
                                                                                                                                             Z 
……………………………………………………………………………………  [1 mark]

(iv)       Draw the atomic structure of atom Z.





                                                                                                                                    [1 mark]

(c)                    Atom X and atom Y are isotopes of an element.
(i)                 What is the proton number of atom X?

……………………………………………………………………………………  [1 mark]

(ii)               Write the electron arrangement of atom Y.

……………………………………………………………………………………  [1 mark]

(iii)             What is valence electron of atom X?

……………………………………………………………………………………  [1 mark]

(iv)             Why atom X and atom Y has same chemical properties?

…………………………………………………………………………………… [1 mark]
                                                                                   
(v)               State one use of the isotope X in archaeology field.

…………………………………………………………………………………… [1 mark]
2          Diagram 2 shows the chemical symbols which represent three elements X, Y and Z
            The letters used are not the actual symbols of the elements.               
           
  9
     X
  4

32
     Y
15

31
     Z
15
                                                                    Diagram 2

(a)          (i)     What is meant by proton number?

                         ……………………………………………………………………………………     [1 mark]

                        (ii)     State the proton number for atom X
                
                      ……………………………………………………………………………………… [1 mark]

(b)   What is represented by the number 32 for the element  Y?

……….……………………………………………………………………………………  [1 mark]

(c)          (i)    Atom Y and Z are isotopes. State the difference between the two atoms.
                       
                   ..……………………………………………………………………………………… [1 mark]

                         (ii)   State one use of isotopes in daily life. 

                    ……………….………………………………………………………………………  [1 mark]

(d)           (i)    Write the electron arrangement of atom Y.
         
                                  ………………………………………………………………………………………  [1 mark]

                          (ii)  Determine the number of valence electron for atom Y.

                     ………………………………………………………………………………………  [1 mark]

                     (ii)  Draw the electron arrangement for atom Z.




                                                                                                                              

[2 marks]

3          Diagram 3.1 shows the arrangement of particles of substance X at different temperatures.                
 

           






(a)                What is the physical state of substance X at
                        (i)         60 oC   : .........................................................................

                        (ii)        90 oC   : .........................................................................                                         [2 marks]
                                                                                                                                                                           
            (b)        State the movement of particles of substance X at 60 oC.
                       
                        ....………………………………………………………………………………………    [1 mark]

            (c)        Graph 3.2 shows the graph of temperature against time when substance X is heated                                      from 60 oC to 90 oC.   
                       











                        (i)         What is meant by melting point?
                                                             ……………………………………………………………………………………………..
                                                ……………………………………………………………………………………[1 mark]

                        (ii)        Based on Graph 3.2, state the melting point of substance X.
                         …………………………………………………………………………………… [1 mark]

                        (iii)       Explain why the temperature remains constant from t1 to t2.

                                    ...................................................................................................................................

                                    ................................................................................................................................[2 marks]

            (d)        (i)         Substance X cannot conduct electricity in any state.
                                    State the type of particles of substance X.
                                                           
                                    ..................................................................................................................................[1 mark]
                        (ii)        Table 3.3 shows two substances.
                                               
Magnesium oxide

Carbon dioxide

Table 3.3
 


                                    Which substance has the same type of particles as substance X?
                                    Tick (√ ) the correct answer.
[1 mark]