According to the above summary of quantum mechanics, we can know the electrons outside of the nucleus are on different orbitals. Different electons on different orbitals have different amoun of energy; this principle is known as the "difference orbital." When the atom's electons are all at the lowest energy level, this is known as the ground state. When some of the electons on the nucleus are on higher orbitals, it is called the excited state. Oviously, there can only be one basic structure of the atom, but there can be numerious excited state. These are known as the first excited state, second excited state. third excited state, etc... The picture 5,1 (n> 2) shows the second excited state of hydrogen.
When the lower electronegativity excited metals (such as Potassium and Sodium) and high electronegativity non-metals （such as flourine and chlorine) get closer to each other, the metals become cations, and the non-metals become anions.When the cations and anions combine, they form an ionic compound. This kind of electostatic pull is called ionic bond. Ionic Bond do not have directions and can be find in ionic solid.
我不明白第三段, 还有离子键是有方向性.
查查看你资料吧, 有些是错的
goodluck, hope its not too late