Because the calcium ion donates two electrons to achieve the stable state. So the layer of electrons decrease form 4 layers(2,8,8,2) to 3 layers(2,8,8). Thus, the radius of a calcium ion is smaller than a calcium atom.
11. D
12.C
13. For 13 i would say B but not so sure
14. A
OK,lisen to me slowly,
all define you.all thing
1.Look at peridoic table which one is solid or others.
For example:hydrogen is air.
And you gonna explain what is hydrogen,
2.After look periodic table you will be able to know every element.
3.Dont forget to check your homework.!!