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## End of chapter exercises

Explain the meaning of each of the following terms

1. ionic bond
2. covalent bond

a) Bonding that occurs between two atoms with a difference in electronegativity greater than 1.7

b) Bonding that occurs between two atoms with a difference in electronegativity of between 0 and 1.7

Which ONE of the following best describes the bond formed between carbon and hydrogen?

1. metallic bond
2. covalent bond
3. ionic bond
a.

covalent bond

Which of the following reactions will not take place? Explain your answer.

1. $H+H→H 2$

2. $Ne+Ne→Ne 2$

3. $Cl+Cl→Cl 2$

Reaction b will not take place as neon does not have electrons available for bonding. Neon is a noble gas and has a full outer shell of electrons.

Draw the Lewis structure for each of the following:

1. calcium

2. iodine

3. hydrogen bromide $(HBr)$

4. nitrogen dioxide $(NO 2 )$

Note that number d could also have the double bond to the other oxygen atom. Both these structures are acceptable. What learners MUST NOT draw for d is two double bonds between the nitrogen and oxygen atoms. There is only ONE double bond and it alternates between the oxygen atoms.

Given the following Lewis structure, where X and Y each represent a different element:

1. What is the valency of X?

2. What is the valency of Y?

3. Which elements could X and Y represent?

a) X has a valency of 1.

b) Y has a valency of 3.

c) X could be hydrogen and Y could be nitrogen.

Complete the following table:

Table 1
 $K +$ $Ca 2+$ $NH 4 +$ $OH -$ $O 2-$ $NO 3 -$ $PO 4 3-$
Table 2
 $K +$ $Ca 2+$ $NH 4 +$ $OH -$ $KOH$ $Ca(OH) 2$ $NH 4 OH$ $O 2-$ $K 2 O$ $CaO$ $(NH 4 ) 2 O$ $NO 3 -$ $KNO 3$ $Ca(NO 3 ) 2$ $NH 4 NO 3$ $PO 4 3-$ $K 3 PO 4$ $Ca 3 (PO 4 ) 2$ $(NH 4 ) 3 PO 4$

Potassium dichromate is dissolved in water.

1. Give the name and chemical formula for each of the ions in solution.

2. What is the chemical formula for potassium dichromate?

1. Potassium ion: $K +$

Dichromate ion: $Cr 2 O 7 2-$

2. $K 2 Cr 2 O 7$