They are two representatives of the sublevels/energy levels.
When you see a long dash joining two elements in the structural formula of a chemical molecule you can assume that the chemical bonds in the compound are simple bonds.
In the representation of chemical molecules long dashes are used to represent simple bonds since these bonds are longer than double and triple bonds, which are represented by = and ≡ respectively.
When the electron absorbs a photon it goes from a lower energy state to a higher one.
They are also called the noble gases or inert gases. They
are virtually unreactive towards other elements or compounds. They are found in
trace amounts in the atmosphere. Their elemental form at room temperature is
colorless, odorless and monatomic gases. They also have full octet of eight
valence electrons in their highest orbitals so they have a very little tendency
to gain or lose electrons to form ions or share electrons with other elements
in covalent bonds.
