chapter 6: ionic bonding

Question 1

What are noble gases?

Answer 1

• noble gases are monatomic
  > exists as individual atoms
  > stable and unreactive
• do not usually react with other elements to form compounds
• elements of group 0: Helium (He)
  , Neon (Ne)… etc

Question 2

How do atoms achieve the electronic configuration of noble gases?

Answer 2

• atoms of elements (except for noble gases), do not have fully filled outer shells
• they are reactive
  > undergo reactions to achieve stable electronic configuration of a noble gas
  1. Losing outer electrons
  2. Gaining outer electrons
  3. Sharing outer electrons

Question 3

READ AND UNDERSTAND!
- atom becomes an ion if it loses or gains electrons
> number of protons and electrons are different
> ions carry a positive charge or a negative charge
- metals form positively charged ions ( cations) and non-metals form negatively charged ions (anions)

Answer 3

The chapter you’re learning today is going to save someone’s life tomorrow. So pay attention.

Question 4

What is 1. duplet electronic configuration and
2. octet electronic configuration?

Answer 4

1.has two outer electrons
>helium
2. Atoms of noble gases have 8 outer electrons

Question 5

How are positive ions formed?

Answer 5

• cations formed when atoms lose electrons
• atoms of metals generally only have a few outer electrons
  > tend to lose electrons to form cations
• when an atom loses electrons, it has more protons than electrons
  > positive ion
• the charge on a cation corresponds to the number of electrons the atom loses

Question 6

How are negative ions formed?

Answer 6

• anions formed when atoms gain electrons
  > generally, non-metals have more than 4 outer electrons
  > tend to gain electrons to form anions
  >more electrons than protons
  >anion is formed

Question 7

Draw a dot diagram of
1. Chlorine atom > _______ ion
2. Oxygen atom > _______ ion

Answer 7

1. Chloride ion
2. Oxygen ion

Look at page 93 of textbook

Question 8

What are ionic bonds?

Answer 8

• are the strong electrostatic forces of attraction between positive and negative ions

Question 9

Draw a dot-and-cross diagram of the formation of sodium chloride.

Answer 9

Things to remember when drawing:

Page 97

Question 10

Draw a dot-and-cross diagram of the formation of magnesium chloride.

Answer 10

Things to remember when drawing:

Page 97

Question 11

Draw a dot-and-cross diagram of
1. Sodium atom > sodium ion
2. Magnesium atom > magnesium ion

Answer 11

Refer to page 92 of tb :)

Question 12

what are polyatomic ions and what are some examples of it?

Answer 12

• ions composed of two or more covalently bonded atoms
  eg: ammonium ion (NH₄⁺), carbonate ion (CO3 2-), sulfate ion ( SO₄²-)
  pg 95 of tb :)

Question 13

turn to page 97 & 98 on general rules for chemical formulae of ionic compounds

Answer 13

yes

Question 14

how do we deduce the chemical formula of an ionic compound?

Answer 14

• all the positive charges must be equal to the negative charges in an ionic compound
  > construct the formula of an ionic compound by balancing the charges on the positive ions with those on the negative ions

Question 15

deduce the chemical formula of :
(i) calcium chloride
(ii) aluminium oxide
(iii) magnesium oxide
(iv) copper (II) hydroxide
(v) ammonium sulfate
(vi) calcium carbonate

Answer 15

(i) calcium chloride: CaCl2
(ii) aluminium oxide: Al₂O₃
(iii) magnesium oxide: MgO
(iv) copper (II) hydroxide: Cu(OH)₂
(v) ammonium sulfate: (NH₄)₂SO₄
(vi) calcium carbonate: CaCO3

page 99 of tb :)

Question 16

what is the formula of these cations?
1. ammonium
2. copper (II)
3. iron (III)
4. chromium (III)

Answer 16

1. NH₄⁺
2. Cu 2+ (2+ on top)
3. Fe 3+ (3+ on top)
4. Cr 3+ (3+ on top)

Question 17

what is a giant ionic lattice structure?

Answer 17

• it is a three dimensional network of ions
• ions packed together in a regular and repeating pattern
• giant lattice structure held together tightly together and ions held in fixed positions
  > cuz the oppositely charged ions attract one another strongly

pg101

Question 18

how can we deduce the formula of sodium chloride from its lattice structure?

Answer 18

• To deduce the formula
  > can determine the ratio of sodium ions to chloride ions in a formula unit
  in lattice structure of sodium chloride:
• each Na+ ion is surrounded by six Cl- ions
  -each Cl- ion is surrounded by six Na+- ions
• the overall ration of sodium ions to chloride ions is 1:1
• formula of sodium chloride: NaCl

Question 19

What are the physical properties of ionic compounds?

Answer 19

1. most ionic compounds have high melting and boiling points
   - in ionic compounds, the forces of attraction between oppositely charged ions > strong
   - large amount of heat is needed to overcome the strong forces of attraction to melt the ionic compound
   - due to high b.p and m.p
   > most ionic compounds are solids at room temperature and pressure
   > ionic compounds are non volatile
2. are usually soluble in water and insoluble in solvents
   > usually soluble in water BUT ionic compounds like
   > silver chloride and barium sulfate is insoluble in water
   - insoluble in organic solvents such as:
   >oil, petrol, turpentine
3. conduct electricity when molten or in aqueous solution ( dissolved in water)

Question 20

why are most ionic compounds soluble in water and insoluble in solvents?

Answer 20

• water molecules are attracted to ions
  > weakens the electrostatic forces between the ions
  > ions pulled from the lattice structure compound dissolves to form an aqueous solution
• in organic solvents, no water present
  > insoluble in them and remain tightly held in the lattice structure

Question 21

why do ionic compounds conduct electricity when molten or dissolved in water? but not in solids?

Answer 21

• there must be free moving ions or electrons in order to conduct electricity
• when it is molten or dissolved in water to form an aqueous solution
  > cations and anions are free to move and are able to conduct electricity
• however, there are no free moving ions to conduct electricity in the solid state since the ions are held in place in the lattice structure

Question 22

what are the formula of these anions:
1. hydrogen carbonate
2. hydroxide
3. nitrate
4. carbonate
5. sulfate
6. phosphate

Answer 22

1. HCO3 - ( - on top)
2. OH - ( - on top)
3. NO3 - ( - on top)
4. CO3 2- ( 2- on top)
5. SO4 2- ( 2- on top)
6. PO4 3- ( 3- on top)

Question 23

what do chemical formulas show?

Answer 23

the number of atoms and the type of elements in a compound

Question 24

what are the chemical formulas for the following acids:
1. Hydrochloric acid
2. nitric acid
3. Phosphoric acid
4. Sulfuric acid

Answer 24

1. HCl
2. HNO3
3. H3PO4
4. H2SO4