If elements have the same number of valance electrons they will have similar but not the same types of chemical reactions.
The valance electrons help to determine the types of chemical reactions that will affect an element.
The group VII A is a good example of this principle.
Fluorine in the second period has 7 valance electrons. Fluorine normally has a charge of -1 undergoing a reduction reaction gaining electrons. Because Florine has the highest electron negativity of all elements no other element can take electrons from Fluorine
Chlorine in the third period has 7 valance electrons. Chlorine normally has a charge of -1. undergoing a reduction reaction gaining electrons. However because Chlorine has an electron negativity of 3.0 both Oxygen and Fluorine have a higher electro negativity and can take electrons from Chlorine. This causes Chlorine to also form +1, +3 +5 and +7 charges.
Though similar elements in the same family or group do not have exactly the same chemical reactions. The shielding affect of increasing electron shells makes the element in each subsequent period less electro negative than the element above it on the periodic table, changing its chemical reactions.