Group 2: Alkaline earth metals

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I was wondering why the beryllium atom in beryllium chloride only has 4 outer electrons?

Igloo says
 
Beryllium chloride
The beryllium atom has only two outer electrons. When these are lost to the two chlorine atoms, Be²⁺(Cl^-)₂ is formed. Now, the beryllium ion is tiny, since all it contains is a first shell of two electrons. Having a very high charge density, it draws electron density back from the two chloride ions. We call this polarization, and say that the small highly-charged beryllium ion has polarized the two chloride ions. The effect of this is that the doubly-positive charge on the beryllium is partially neutralized, and the bonding is therefore more covalent in character. This is why you will usually see the structure shown as two covalent bonds:
 
Cl – Be – Cl , and the dot and cross diagram as being Cl : Be : Cl
Each pair of electrons (:) in the previous diagram should really be a dot and a cross rather than two dots, but I haven’t the facility to show this easily in an email answer.
 
You can think of the bonding in beryllium chloride as being ionic bonding with considerable covalent character or as being covalent some ionic character. Most chemsits think of the bonding in this compound as being mainly covalent.
 
At A-level you should begin to realize that ionic and covalent are two extremes of bonding, but that all bonds involve a bit, or sometimes a great deal of both types.
 
However note that there are lone pairs of electrons on each chlorine atom. In the solid state the compound does not consist of BeCl₂ molecules. In effect the molecuels polymerise with each chlorine atom forminf a dative bond to a beryllium atom. So each beryllium atom does have four pairs of electrons round it: two pairs from the covalent bonds, two pairs from the dative bonds. For a diagram and fuller explanation see this tutorial by Jim Clark.

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updated: 30 January 2006