Chemistry form 4 Text Book Answer 2

Quick Review D, pg 72

1. (a)  Element E has a higher melting and boiling points than element D.  This is because the atomic size of E is greater than D, the forces of attraction becomes stronger.  Thus, more heat energy is needed to overcome the forces of attraction.

(b)  2Fe  +  3D₂    →  2FeD₃

  

2. (a)  They have the same number of valence electrons.

(b)  Iodine is placed below bromine in Group 17. The atomic size of iodine is greater than bromine.  Thus, the outermost occupied shell of iodine becomes further from the nucleus.  Therefore, the strength to attract one electron into the outermost occupied shell becomes weaker.  This causes the reactivity of iodine is less than bromine.

  

3. (a)  -    It is black in colour.

-          It exists in solid form.

-          It has low melting and boiling points.

(b)   Yes.  Astatine reacts with hot iron to form a brown solid, iron(III) astatide.