Human chromosomes are divided into 7 groups & sex chromosomes

A 1-3 Large metacentric 1,2 or submetacentric

B 4,5 Large submetacentric, all similar

C 6-12, X Medium sized, submetacentric - difficult

D 13-15 medium-sized acrocentric plus satellites

E 16-18 short metacentric 16 or submetacentric 17,18

F 19-20 Short metacentrics

G 21,22,Y Short acrocentrics with satellites. Y no satellites.