The evidence of chemical changes with an example of each (include all 5)

Write the chemical symbols for three different atoms or atomic cations with 27 electrons. asap!

Which of the following statements is false regarding aromaticity? a. the compound must be cyclic b. the compound must be fully conjugated c. the compound must be planar d.the number of electrons in the pi system must satisfy the hückel 4n+2 rule e. the compound must have a neutral charge

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d