Answer:
Explanation:
1.  
a. When a sulphur atom gains two electrons, it becomes negatively charged to form an anion called sulphide ion and it’s represented as S2-.  
b. When an aluminium atom loses three electrons, it becomes positively charged to form a cation and it is represented as Al3+.  
c. When a nitrogen atom gains three electrons, it becomes negatively charged to form an anion called nitride ion and it is represented as N3-.  
d. When a calcium atom loses two electrons, it becomes positively charged to form a cation and it is represented as Ca2+  
2.  
• When Iron (Fe) loses two electrons, it becomes Fe2+ and the electronic configuration will be 1S2 2S2 2P6 3S2 3P6 3d6  
• When Cobalt (Co) loses two electrons, it becomes Co2+ and the electronic configuration will be 1S2 2S2 2P6 3S2 3P6 3d7  
• When Nickel (Ni) loses two electrons, it becomes Ni2+ and the electronic configuration will be 1S2 2S2 2P6 3S2 3P6 3d8  
3.  
•When Chromium (Cr) loses three electrons, it becomes  Cr3+ and the electronic configuration will be 1S2 2S2 2P6 3S2 3P6 3d3
• When Manganese (Mn) loses three electrons, it becomes Mn3+ and the electronic configuration will be 1S2 2S2 2P6 3S2 3P6 3d4  
4.  
•Bromine (Br) gains an electron to become Br-  
•Hydrogen (H) gains an electron to become H-  
•Arsenic (As) gains three electrons to become As3-  
•Selenium (Se) gains two electrons to become Se2-