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Chemistry Form 4 • MODULE

(ii) State one physical property of the compound / Nyatakan satu sifat fizik sebatian tersebut.
Low melting/boiling point // does not dissolve in water // dissolves in organic solvents // does not conduct
electricity in aqueous solution or molten state.
(f) When element G is burnt in L gas, G burns rapidly and brightly with a yellow flame and produces white fumes.
Apabila unsur G dibakar dalam gas L, G terbakar cergas dengan nyalaan kuning terang dan menghasilkan wasap putih.
(i) Write the equation for the reaction between element G and gas L.
Tuliskan persamaan kimia bagi tindak balas antara unsur G dan gas L.
4G + L 2G L .
2 2
(ii) Explain how a compound is formed between elements G and L based on their electron arrangement.
Jelaskan dari segi susunan elektron bagaimana unsur G dan L bergabung membentuk sebatian.
– The electron arrangement of G atom is 2.8.1. G atom is not stable. G atom releases one valence electron to

form G ion and achieve stable octet electron arrangement 2.8.
+
– The electron arrangement of L atom is 2.6. L atom is also unstable. L atom receives 2 electrons to form L
2–
ion and achieves a stable octet electron arrangement 2.8.8.

– Therefore two G atoms release two electrons to one L atom, a strong electrostatic force is formed between
G and L ions.
+
2–
(iii) Draw the electron arrangement of the compound formed / Lukiskan susunan elektron bagi sebatian yang terbentuk.
+ 2– +

G L G

(g) Compare the boiling point of the compounds formed in 1(d) and 1(e). Explain your answer.
Bandingkan takat didih sebatian yang terbentuk di 1(d) dan 1(e). Jelaskan jawapan anda.
– The boiling point of compound G L is high and EL is low.
2 2
– The boiling point of compound G L is high because positive ions and negative ions are attracted by strong
2
electrostatic force. Large amount of energy is needed to overcome it.
– The boiling point of EL is low because the molecules are attracted by weak Van der Waals forces, small amount
2
of energy is needed to overcome it.

2 The diagram below shows the electron arrangement of compound A. Compound A is formed from the reaction between
element X and element Y.
Rajah di bawah menunjukkan susunan elektron bagi sebatian A. Sebatian A terbentuk dari tindak balas antara unsur X dan unsur Y.
+ –

X Y

(a) (i) Write the electron arrangement for atom of elements X and Y / Tuliskan susunan elektron bagi atom unsur X dan Y.
X: 2.8.1 Y: 2.8.7
(ii) Compare the size of atoms of elements X and Y. Explain your answer.
Bandingkan saiz atom unsur X dan unsur Y. Jelaskan jawapan anda.
– Atom Y is smaller than atom X.
– Atom X and atom Y have the same number of shells occupied with electrons.

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