Wednesday_18: Lesson 14 Covalent compounds

• Chemistry
• Secondary Education

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CHEMISTRY 10

12 - Formulae of Ionic Compounds

• I can deduce the formula of an ionic compound from the relative numbers of the ions present in a model or a diagrammatic representation or from the charges on the ions.

Write the chemical formulae of the following ionic compounds.

Valency (Combining Power)

Valency (Combining Power)

Ion 1	Ion 2	Formula	Ratio
zinc (II)	chloride
magnesium	carbonate
ammonium	sulfate

Writing Chemical Formulae of Binary ionic compounds

Write a balanced formula for a compound that contains calcium and each of the following elements.

• (a) oxygen 
• (b) sulfur 
• (c) chlorine
• (d) bromine
• (e) phosphorus
• (f)  fluorine

1.  Write the unbalanced formula. Place brackets around any polyatomic ions that are present.
2.  Write the valence of each ion above it. 
3.  Cross over, and write the subscripts.
4.  Tidy up the formula. Remember that you omit the subscript if only one particle exists in the ionic compound or molecule. Here, the brackets are no longer needed so that they can be removed.

lithium +

• nitrate
• hydroxide
• carbonate
• sulfate
• phosphate

magnesium +

• nitrate
• hydroxide
• carbonate
• sulfate
• phosphate

Writing Chemical Formulae involving Compound ions

Write a chemical formula for a compound that contains sodium and each of the following polyatomic ions:

(a) nitrate 

(b) sulfate 

(c) hydroxide

(d) phosphate 

(e) carbonate

Writing Chemical Formulae involving Compound ions

A. Write the valences for the elements in each compound. If the compound is ionic, indicate the charge associated with each valence.

• SAMPLE: (1) AgCl 
• (2) TiO2 
• (3) CaO
• (4) Mn3P2 
• (5) FeS

B. Write the chemical formula of each compound.

• (6) tin (II) fluoride
• (7) barium sulfate
• (8) hydrogen chloride
• (9) caesium bromide
• (10) ammonium nitrate

+1

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CHEMISTRY 10

14 - Formulae of Covalent Compounds

• I can deduce the formula of a simple compound from the relative numbers of atoms present in a model or a diagrammatic representation.
• *I can name chemical compounds based on IUPAC rules.

Name the following covalent compounds.

How many atoms of different elements are there in the formulae of the following compounds?

CO_{2 (g)}

How many atoms of different elements are there in the formulae of the following compounds?

NH_{3 (g)}

How many atoms of different elements are there in the formulae of the following compounds?

C₆H₁₂O_{6 (s)}

How many atoms of different elements are there in the formulae of the following compounds?

HCl _(g)

How many atoms of different elements are there in the formulae of the following compounds?

NO₂

The dot-and-cross diagram helps keep track of electron sharing in bonding and ensures that the octet rule is obeyed.

Lewis Structure

Structural diagram

Ball-and-Stick Model

Space-filling model

Name the following compounds.

How many atoms of different elements are there in the formulae of the following compounds?

NaCl

How many atoms of different elements are there in the formulae of the following compounds?

BeCl2

How many atoms of different elements are there in the formulae of the following compounds?

CaO

How many atoms of different elements are there in the formulae of the following compounds?

Al2O3

How many atoms of different elements are there in the formulae of the following compounds?

ZnCl2

How many atoms of different elements are there in the formulae of the following compounds?

ZnCl2

• BEFORE: no rules for naming compounds
• NOW: International Union of Pure and Applied Chemistry (IUPAC) rules

Naming chemical compounds

Common chemical compounds

Naming Metals in Chemical Compounds: The Stock System

Group I (+1)

• Lithium
• Sodium
• Potassium
• Rubidium
• Caesium

Group II (+2)

• Beryllium
• Magnesium
• Calcium
• Barium
• Radium

Group III (+3)

• Aluminium
• Gallium
• Indium
• Thallium

Transition metals

• ?

Naming Metals in Chemical Compounds: The Stock System

Transition metals

• Scandium (III)
• Titanium (III)
• Vanadium (II)
• Vanadium (III)
• Vanadium (IV)
• Vanadium (V)
• Chromium (II)
• Chromium (III)
• Chromium (VI)

Transition metals

• Manganese (II)
  
• Manganese (VII)
• Iron (II)
• Iron (III)
• Cobalt (II)
• Cobalt (III)
  
• Nickel (II)
• Copper (I)
• Copper (II)
• Zinc (II)

Naming Non-Metals in Chemical Compounds

Group IV (- 4)

• Carbon → carbide

Group V (- 3)

• Nitrogen → nitride
• Phosphorus → phosphide

Group VI (- 2)

• Oxygen → oxide
• Sulfur → sulfide
• Selenium → selenide

Group VII (- 1)

• Fluorine → fluoride
• Chlorine → chloride
• Bromine → bromide
• Iodine → iodide
• Astatine → astatide

Putting it together!

Write the IUPAC name for each compound.

• (a) Al2O3 
• (b) CaBr2 
• (c) Na3P
• (d) Cu2S 
• (e) Mg3N2
• (f) HgI2

Try these ones!

Write the IUPAC name for each compound.

• (a) (NH4)2 SO4 
• (b) Al2 (NO3)3 
• (c) Li2 CO3
• (d) Ni (OH)2 
• (e) Ag3PO4

Naming Binary Compounds That Contain Two Non-Metals

Write the IUPAC name for each compound.

• (a) SF6 
• (b) N2O5
• (c) PCl5 
• (d) CF4
• (e) P2O5
• (f)  PBr3

Write the IUPAC name for each compound.

• (a) CsF
• (b) NaSO4
• (c) NiCl2
• (d) NF3