They exhibit similar chemical properties. Elements within the same period have different number of electrons in their valence shells (the number is increasing from left to right) and different valence shell electron configuration. Therefore, elements in the same period are chemically different.

Do elements in the same group share physical properties?

Each element within a group has similar physical or chemical properties because of its atom's outermost electron shell (most chemical properties are dominated by the orbital location of the outermost electron).

What do elements in the same period have in common?

Like PERIODic table.). All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.