1. Science 3200
Unit 1 Part 2

2. Bonding Bonding of elements is the attraction between atoms or ions
Bonds that are formed between two non-metals (i.e. elements found to the right of the ladder on the periodic table) result in molecular compounds
Bonds that are formed between a metal and a non-metal (i.e. one from the left and one from the right of the ladder) result in ionic compounds

3. Bonding Ex. State whether each compound is molecular or ionic. NaCl
CF4
LiBr

4. Bonding
Some atoms will combine with other atoms of the same element. These atoms are found in nature like this. These are:
Hydrogen (H2) - Bromine (Br2)
Nitrogen (N2) - Iodine (I2)
Oxygen (O2) - Astatine (At2)
Fluorine (F2) - Phosphorus (P4)
Chlorine (Cl2) - Sulfur (S8)

5. Bonding Covalent Bonding (Molecular Compounds) Sharing of electrons
the two non-metals both want to gain electrons (to be like the noble gases), since both cannot gain electrons at the same time they share.
The unit formed by a covalent bond is called a molecule (it is neutral; it has no charge)

6. Bonding
Ionic Bonding
Gaining and losing electrons to form stable compound
The unit formed by an ionic compound is a formula unit
These form neutral compounds by the number of electrons lost is equal to the number taken up

7. Compounds Molecular Compounds
Involve the sharing of electrons resulting in covalent bonding
Composed of two non-metals
Exist as individual molecules
May or may not be in lowest whole number ratios

8. Naming Molecular Compounds
Mono-atomic elements
Mono means one, so these are elements that exist on their own in nature.
Namely the noble gases:
He – helium
Ne – neon
Ar – argon
Kr – krypton
Xe – xenon
Rn – radon
No need to memorize these as they are listed in the periodic table

9. Naming Molecular Compounds
Diatomic molecular compounds
These are non-metals that exist in nature as two atoms joined together.
They are:
H2 – hydrogen
O2 – oxygen
N2 – nitrogen
Cl2 – chlorine
F2 – flourine
Br2 – bromine
I2 - iodine

10. Naming Molecular Compounds
Polyatomic molecular elements
These are non-metals that exist in nature with many atoms joined together
These are:
S8 – sulfur
O3 – ozone
P4 – phosphorus (red)

11. Naming Molecular Compounds
Trivial names
These are names on compounds that do not follow the guidelines put out by IUPAC.
These are:
H2O – water
H2O2 – hydrogen peroxide
NH3 – ammonia
C12H22O11 – sucrose
CH4 – methane
CH3OH – methanol
C2H5OH - ethanol

12. Naming Molecular Compounds
For binary molecular compounds, we use prefixes to indicate the number of atoms that are present in the compound. These are:
Mono – one
Di – two
Tri – three
Tetra – four
Penta – five
Hexa – six
Hepta – seven
Octa – eight
Nona – nine
Deca - ten

13. Naming Molecular Compounds
When writing the name of a molecular compound start with the first element, not changing the name, except for adding the prefix. Then write the name of the second element with the prefix and changing the ending of the name to –ide.
Note: the prefix mono on the first element only is optional.

14. Naming Molecular Compounds
For example, name the compound CCl4
The first element is carbon and there is only one of them.
The second element is chlorine and there are 4 of them. Therefore the name would be
monocarbon tetrachloride or
carbon tetrachloride

15. Naming Molecular Compounds
Ex 2. Write the name for P4F6. Sol’n: The first element is phosphorus and there are four atoms. The second element is fluorine and there are six atoms. Therefore the name of this compound is: tetraphosphorus hexafluoride

16. Naming Molecular Compounds
Your turn. Name each of the following.
P4F5
C2O4
NO3
Cl2O
N3Br2
O6I2

17. Writing Molecular Formulas
When writing molecular formulas you look up each element on the periodic table to determine the chemical symbol for the element. (Don’t forget that the ending on the second element has been changed to –ide)
Use the prefix on each element to determine the number of atoms present. Write this number to the right of the symbol and as a subscript.

18. Writing Molecular Formulas
Ex. Write the formula for diboron hexahydride. The first element is boron which is B and di means 2. The second element is hydride (or hydrogen) which is H and hexa means 6.  We have B2H6

19. Writing Molecular Formulas
Ex. Write the formula for nitrogen triiodide. The first element is nitrogen which is N and since there is no prefix there is only one. The second element is iodide (or iodine) and tri means 3.  We have N1I3 or NI3.

20. Writing Molecular Formulas
Your turn. Write the formulas for each of the following.
Carbon disulfide
Dinitrogen pentabromide
Silicon trifluoride
Hexaphosphorus pentachloride

21. Ionic Compounds Ionic Compounds:
Involve the transfer of electron(s), i.e gaining and losing electrons, resulting in ionic bonding
Made up of two oppositely charged ions (metal and non-metal, or combination involving a polyatomic ion)
Are always written as empirical formulas (lowest whole number ratio)

22. Naming Ionic Compounds
There are two categories of ionic compounds that we will deal with.
1. Binary ionic
Simple ions (only single charges)
2. Polyatomic ions (complex ions)

23. Naming Ionic Compounds
Binary ionic compounds are composed of a metal ion (+) and non-metal ion (-).
Binary simply means that only 2 ions are involved.
Ex. NaCl – the combination of a sodium ion and a chloride ion.

24. Naming Ionic Compounds
Rules for naming simple binary ionic compounds (meaning a compound with only two elements):
Name the metal (+) by writing the full name of the metal.
Name the non-metal (-) by shortening the name of the atom and adding the –ide ending.

25. Naming Ionic Compounds
Ex. NaCl  sodium chloride
CaF2  calcium fluoride
K2O  potassium oxide
**Note: Do NOT use prefixes – they are for molecular compounds only (i.e. two non-metals)

26. Naming Ionic Compounds
Your turn. Name the following:
LiBr
AlCl3
Rb2S
Mg3P2
CaO

27. Writing Ionic Formulas
Rules for writing binary ionic formulas:
Write down the symbols of the ions involved.
Cross over the charges and write as subscripts.
Determine the lowest whole number ratio of ions that will give a net charge of zero.
You do not need to write 1’s.

28. Writing Ionic Formulas
Ex. 1) Write the chemical formula for potassium bromide. 2) Write the chemical formula for calcium oxide. 3) Write the chemical formula for magnesium iodide.

29. Writing Ionic Formulas
Your turn. Write the chemical formula for each compound:
Sodium sulfide
Aluminum bromide
Barium iodide
Magnesium nitride
Aluminum nitride

30. Naming Compounds with Polyatomic Ions
A polyatomic ion is two or more atoms covalently bonded together that carry an overall charge. Since they have a charge they can gain or lose electrons to form ionic compounds.
These ions are listed on your sheet but this list is not exhausted, i.e. There are more polyatomic ions than what’s listed.

31. Naming Compounds with Polyatomic Ions
To identify these compounds look at the elements involve. If you have more than two elements in the compound and the compound is not in your trivial names list than it contains a polyatomic ion.
You name these the same way you name ionic compounds: look up the element/polyatomic ion and write the names down changing the second name to have the ending –ide.

32. Naming Compounds with Polyatomic Ions
Ex 1. (NH4)3PO4 Ex 2. Cr(NO3)3

33. Naming Compounds with Polyatomic Ions
Your turn. Write the name of the following compounds.
Zn(OH)2
Pb(NO3)2
Mg(CH3COO)2
Na3BO3
K2Cr2O7

34. Writing Compounds with Polyatomic Ions
When writing the formulas for compounds containing a polyatomic ion(s), you treat the ion as a single unit, not as individual elements.
If you need to write a subscript for a polyatomic ion, then you must enclose the ion in brackets.
Remember to use the charges on the polyatomic ions to determine how many you need to have a balanced compound, NOT the subscripts!!!

35. Writing Compounds with Polyatomic Ions
Ex 1. sodium chlorite Ex 2. iron (III) sulfate Ex 3. ammonium permanganate

36. Writing Compounds with Polyatomic Ions
Your turn. Write the formula for each of the following.
Sodium hydroxide
Potassium bicarbonate
Potassium carbonate
Magnesium hydroxide
Ammonium sulfate