(1)书写下列元素符号:
氢:______; 碳:______;氧:________;钠:__________;镁:________;铝_____:硅:_______;磷:_______;硫:________; 氯:________;钾:________;钙:________;锰:_______;铁:________;铜:_____________;锌:_______;银:___________;钡:____________氮__________汞 ________________
(2)用符号表示
水___氢气___氧气______钠离子_____