1. Elements combine to form compounds
Chapter 3
Elements combine to form compounds

2. What you will learn Distinguish between covalent and ionic compounds
Demonstrate understanding of chemical names and formulas of ionic compounds
Differentiate between chemical and physical changes

3. Objectives By the end of the lesson you should be able to:
Describe compounds
Compare and contrast ionic and covalent compounds
Describe polyatomic ions

4. Importance
Almost everything in our world is made of compounds and mixtures of compounds
Our society depends on the production and wise use of compounds

5. Recall: Metals vs Non-metals
Metals have positive (+) ion charges.
Therefore, they want to donate an e- from their outer shells.
Most non-metals have negative (–) ion charges.
Therefore, they want to accept an e- into their outer shells.

6. Lithium
Lithium will donate 1 e- and Fluorine borrow 1 e-
Fluorine

7. Recall
Compounds are made up of 2 or more elements that have been chemically bonded
Electrons are located in the shells around the nucleus
Only electrons can move – protons and neutrons are “locked” in the nucleus
Golden Rule: all atoms want to have full outer shells and will gain/lose electrons to do achieve this

8. Atomic Structure review
How will sodium achieve a full
outer shell: gain 7 electrons or
lose 1?
Way easier to lose 1, so has an
overall ion charge of 1+
How will fluorine achieve a full
outer shell: gain 1 electron or lose
7 electrons?
Way easier to gain 1, so has an
overall ion charge of 1-

9. Question
Where do the electrons that are gained when making a full outer shell come from??
Where do the electrons that are lost when making a full outer shell go??
ANSWER: from other atoms! But how?

10. Making Compounds There are two ways to make compounds:
Ionic Compounds: electrons can be transferred from one atom (losing electrons) to another atom (gaining electrons)
Covalent Compounds: electrons are shared between two atoms that are both gaining electrons
You never have a situation where two atoms are both losing electrons

11. Ionic Compounds Transfer of electrons from a metal to a non-metal
The metal ions have positive charges because they are losing electrons
The non-metal ions have negative charges because they are gaining electrons
Opposite charges attract so they stick together like magnets!

12. Ionic Bonding Example: Fluorine and Lithium
How many valence electrons does lithium have? 1
How many valence electrons does fluorine have? 7
Thus to gain full outer shells – lithium will donate its outer shell electron to fluorine

13. Ionic Bond
To show an ionic bond draw an arrow to show where electrons are moving from and to
Draw the brackets and show the ion charges formed for each.
Video

14. Your Turn Draw a beryllium and oxygen atom How would they bond?
Draw arrows to show where the electrons would move and the final ionic bond!

15. Ionic Compounds as solids
When ionic compounds occur as solids there are more than one pair of atoms involved
These occur as an “Ionic Lattice”
Notice the + ions and
– ions are in an alternating
pattern
Video

17. Covalent Compounds
What happens when 2 non-metals try to bond when they both need to gain electrons?
They have to share electrons to gain full outer shells!
A molecule is formed when a group of atoms bond together by sharing electrons

18. Covalent Bonding Example: Water (H2O)
How many valence electrons does hydrogen have? 1
How many valence electrons does oxygen have? 6
When hydrogen and oxygen bond how many electrons does oxygen need? 2
How many electrons can hydrogen give to oxygen?
So how many hydrogen atoms are needed to make water?

19. Covalent Bonding Example (Water (H2O)
Notice that the outer shells of each atom are overlapping to show and that the electrons are in that “shared zone”
Video

20. Your turn! Draw the covalent bonds for Ammonia (NH3)

21. Polyatomic Atoms
Covalent and ionic bonds can be found in the same compound!! WOW!...but how?!?!
It is possible for some molecules (groups of atoms bonded covalently) to gain/lose electrons as the atoms combine to form a compound.
So, because they are gaining/losing electrons they are called ions....specifically polyatomic ions
“Poly” means many...so, there are many atoms in this type of ion

22. Polyatomic Atoms There are many types of polyatomic ions.
One kind, Carbonate, helps form the delicate shell of a robin’s egg and the enamel on your teeth called calcium carbonate.
Calcium carbonate carbonate ion

23. Review
Ionic Compounds: bonding between metals and non-metals
Transfer of electrons from metal to non-metal results in ions
Covalent Compounds: bonding between non-metals and non-metals
Electrons are shared
Polyatomic Ions: group of atoms covalently bonded together which form an overall charged molecule – like a big ion!

24. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
NaCl Ionic compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

25. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
MgCl2 Ionic compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

26. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
CCl4 Covalent compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

27. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
MgO Ionic compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

28. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
CO3-2 Polyatomic ion
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

29. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
OH-1 Polyatomic ion
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

30. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
Li2O Ionic compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

31. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
P4O10 Covalent compound
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?

32. QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?
NH4+1 Polyatomic ion
QUIZ Ionic Compound, Covalent Compound, or Polyatomic Ion?