Atomic Symbol
That is called a chemical symbol. It is a shorthand way of representing chemical elements using letters, most commonly derived from the element's name in English, Latin, or another language.
The formula for a single atom is its elemental symbol, which is a one or two-letter abbreviation representing the element (e.g., H for hydrogen, O for oxygen). Each element has a unique symbol that is used to represent it in chemical formulas and equations.
The lower case letter in the symbol represents the subshell that the electron is in. It is a way to indicate the energy level and shape of the electron's orbit. Upper case letters are used for the element's name, while lower case letters are used for subshell designation.
If you are representing a nuclide, then yes. (i.e. If you are representing a symbolic chemical equation, then no. If you are representing an ionic chemical equation, then only the oxidations states. (i.e. valencies)
Oxygen does not have an element symbol of O5. The element symbol for oxygen is simply O, representing its atomic number 8.
phi (φ)
The symbol for neon is Ne and it is the short form for representing the element neon.
CI does not exist. Cl (with a lowercase L) is the element chlorine
The element associated with evil spirits is typically "Darkness" in various mythologies and belief systems. This element is often portrayed as representing malevolence, negativity, and the unknown.
oval
This is the chemical symbol of a chemical element.
Pi is the 16th letter of the Greek alphabet, representing 'p'. It's mathematical use was proposed by Welsh mathematician William Jones in 1706, representing the constant 3.14159.