Acidity change law of halogen acid neither abides by the successive change law of the highest price oxyacid acidity for cognation nonmetal nor conformes to the vivacity successive change law of cognation nonmetal.

• 氢卤酸的酸性强弱规律既不满足同族非金属最高价含氧酸酸性递变规律,又不满足同族非金属活泼性变化规律。