ce chem question!!!

1)
K and F would combine most readily to form an ionic compound.

Among all the elements in the given Periodic table, K is the most reactive metal which loses electrons most readily, and F is the most reactive non-metal which gains electrons most readily.

The most reactive metal and the most reactive non-metal would combine most readily to form an ionic compound.


2)
Group I: potassium (or lithium, or sodium)
Group II: magnesium (or beryllium, or calcium)
Group III: aluminium
Group IV: carbon (graphite)

(Note that silicon is NOT a good conductor. Silicon is a semi-metal which is a semi-conductor.)


3)
There is something wrong in the question:
Be, Mg and Ca are the Group II elements.
Li, Be, B, C, N, O, F and Ne are the 2nd Period elements.

Among the three given Group II elements (Be, Mg and Ca), Be has the highest melting point. The size of Be is the smallest among them, and thus Be has the shortest distance between the nucleus and the delocalized electrons. Therefore, Be has the strongest metallic bonds.

Among the eight 2nd Periodic elements, C (diamond) has the highest melting point. This is because the carbon atoms are held together by a network of strong covalent bonds, and almost all the covalent bonds are broken in melting.

2009-08-03 12:02:07 補充：
3.
The metallic bonds of Li and Be are not very strong, because each Li atom have only one valence electron to make the metallic bonds, while each Be atom have only two. Besides, only part of the metallic bonds is broken in melting.

2009-08-03 12:02:20 補充：
B and C have giant covalent structure, in which all atoms are held together by a network of strong covalent bonds. Besides, almost all strong covalent bonds are broken melting.

2009-08-03 12:02:41 補充：
Therefore, B and C have the highest melting points in the 2nd period. C has a higher melting point than B, because C-C is stronger than B-B bond as the bond length of C-C bond is shorter.

2009-08-03 12:02:53 補充：
N, O, F and Ne have simple molecular structure, in which the molecules or atoms (Ne) are held together by weak van der Waals' force. Therefore, their meting points are low.

2009-08-03 12:05:11 補充：
3.
The metallic bonds of Li and Be are not very strong, because each Li atom have only one valence electron to make the metallic bonds, while each Be atom have only two. Besides, only part of the metallic bonds is broken in melting.

2009-08-03 12:05:25 補充：
B and C have giant covalent structure, in which all atoms are held together by a network of strong covalent bonds. Besides, almost all strong covalent bonds are broken melting.

2009-08-03 12:05:47 補充：
Therefore, B and C have the highest melting points in the 2nd period. C has a higher melting point than B, because C-C is stronger than B-B bond as the bond length of C-C bond is shorter.

2009-08-03 12:06:05 補充：
N, O, F and Ne have simple molecular structure, in which the molecules or atoms (Ne) are held together by weak van der Waals' force. Therefore, their meting points are low.

Your explanation is very clear.
thx a lot~~~

1. Group I metal + Group IV halogens
因為一個gain electron容易,一個lose electron容易
potassium + fluorine

2. Group I: Potassium
Group II: Calcium
Group III: Aluminium
Group IV: Silicon

3. 你係講Group II嗎?因為你打了be, mg, ca
如果係group ii,就係beryllium了. 因為group I同group II metal的melting point decrease down the group,所以beryllium係最高的melting point 了!

2009-07-27 17:47:53 補充：
但係正常情況下,如果沒有給carbon邊隻的話,我唔認為擇carbon lo!因為沒有given是否graphite