According to the Aufbau principle, , electrons orbiting one or more atoms fill the lowest available energy levels before filling higher levels (e.g., 1s before 2s).
Many electrophilic aromatic halogenations require the presence of an aluminum trihalide as a catalyst. We generally acetylated the amino group as protection. Now, this acetanilide can be brominated at Ortho or para position. An atom that is attached to an aromatic system usually hydrogen is replaced by an electrophile is an organic reaction which is called Electrophilic aromatic substitution. There are what you called important electrophilic aromatic substitutions they are aromatic nitration, aromatic sulfonation, aromatic halogenation and acylation and alkylating Friedel-Crafts reaction. Aromatic bromination is an electrophilic aromatic substitution (EAS) reaction, which will require benzene to act as a nucleophile to acquire an electrophile. Therefore, any directing groups that activate the ring will make it react more quickly with respect to aromatic bromination. Acetanilide is a moderately-activated ring <span>having a decent EWG.</span>
Ionic bonds form between two elements that have a very large difference in electronegativity ie. a metal and a non-metal. The electronegative element will want an electron to make it stable whilst the less electronegative element wants to donate an electron to make it stable. Therefore the metallic element donates a electron to the non-metal and both become ions, which attract each other. Eg. Na becomes Na+ and Cl becomes Cl-, the opposite charges attract, forming the bond.
