What is the oxidation number for beryllium?
The oxidation number would be +2
This element is in group 2 which is the alkali-earth metals. These elements want to lose 2 electrons.
Don't let the word "lose" fool you! Electrons are negative. If I lose electrons, I'm losing my negativity and becoming more positive.
By losing 2 negative ions, 2 positive ions move into place and become Be +2
Clarification: This is just a technique I've learned in Chemistry class. However, don't mix up positive with protons.. Note that Be+2 does not mean Be has 2 extra protons. It has 2 extra positive ions and 2 less electrons.