I am not clear with the molecular orbital theory. I have read:
If the atomic orbitals are combined with the same phase they interfere constructively and a bonding orbital is formed.
If the atomic orbitals are combined with different phases, they interfere destructively and an anti-bonding molecular orbital is formed.
So as per my understanding when two s-orbitals are combined either a bonding orbital can be formed or an anti-bonding orbital can be formed depending upon the type of interference. This contradicts the following statement:
When two atomic orbitals combine they form two new molecular orbitals.
This means that when two s-orbitals combine they produce both bonding and anti-bonding orbitals. Where have I gone wrong?