a) in periods; With an increase in the number of electrons at the external energy level of atoms, the metallic properties of chemical elements weaken, and the non-metallic properties increase.
b) in groups; With an increase in the radius of atoms, the metallic properties of chemical elements increase, and non-metallic properties weaken.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.