Writing a formula for a compound that contains calcium ?

Question

hi I need help with this question. How do I write a balanced formula for a compound that contains calcium with each of the following elements, and writing the name for each compound as well. 

 

a) oxygen 

b) bromine 

c) sulfur

d)phosphorus 

e) chlorine

f) fluorine 

Answer 1

Hi Alex, 

You will need to know the number of valence electrons 

Calcium has valence electrons of 2 (you can write down the electronic configuration or look it up in periodic table)

(a) Oxygen has 6 valence electron. it needs 2 electrons to reach an octet state (8 valence electrons) it gets this from the calcium, which will lose the 2 electrons to attain an octet state.

2Ca + O₂ -----> 2CaO

(b) Bromine is in group VII the halides, it has 7 valence electrons, calcium will donate 1 electron to each bromine

Ca + Br₂ ------> CaBr₂

(c) Sulfur is in the same group as oxygen they behave similarly

8Ca + S₈ -------> 8CaS

(d)Phosphorus is in group V

6Ca + P₄  ------> 2Ca₃P₂

(e) Ca + Cl₂ ------> CaCl₂      Chlorine is behaves like bromine, fluorine, iodine

(f) Ca + F₂ --------> CaF₂