1. Chapter 6 Section 1 Compounds and Molecules
Structure of Matter
Chapter 6 Section 1
Compounds and Molecules

2. Chemical bonding A joining of atoms to form new substances (molecules)
This is a chemical change, the new substances will have different properties than the original elements.
Chemical bonding involves valence electrons

3. Why atoms bond?
Atoms are most stable (happy) with a full valence shell.
A full valence is normally 8 e- (for H, He, Li and Be it is 2)
Bonding is an atoms sharing or transferring electrons trying to get to a full valence shell.

4. Types of bonds
Ionic bonding- a transfer of electrons (something gains, something loses)
Metal + Nonmetal
Covalent bonding- a sharing of electrons
2 Nonmetals
Metallic bonding- electrons being shared and transferred throughout a compound
2 Metals

5. Chemical Structure
Water’s chemical formula tells us what atoms make up water, but it doesn’t tell us anything about how it is put together or how it acts.
Chemical Structure: how the atoms are bonded together to make the compound

6. Bond Length and Angle
Bond length: the distance between nuclei of two bonded atoms
Bond Angle: the angle formed by two bonds to the same atom, tells which way these atoms point.

7. Why Bond?
Atoms join to form bonds so that each atoms has a stable electron configuration.
Bill Nye on chemical reactions

8. What are ionic bonds? Ionic bonding- a transfer of electrons
Ionic bonds occur between metals and nonmetals

10. -

11. Chemical Compounds
Chapter 6 section 2

12. Ionic and Covalent Compounds
An element is something that can not be broken down any further. It is made up entirely of the same atom.
Compounds are pure substances composed of the same ions and/or molecules.
Compounds can be broken down into other substances.

13. Ionic and Covalent Compounds
Ionic bonds are a transfer of electrons.
Covalent bonds are a sharing of electrons.
In an ionic bond, an electron leaves one atom and goes to another.
In a covalent bond, the electron travels around two atoms.

14. What holds them together?
bond implies they are stuck together, but there is nothing shared between them.
Ionic bonds are held together by electromagnetic force (opposites attract)
so Na+ is attracted to Cl-
when large amounts get together they stack in a crystal arrangement

15. Crystal Arrangement There isn’t exactly an ionic “molecule”, just
a ratio of loose ions stacked together. They
Make a network. This is sometimes called a
formula unit.

16. Dissolving Ions
If you dissolve ions in water, they will break apart into parts.
Some will have a positive charge, some will have a negative charge.
Because of this difference in charge IONIC COMPOUNDS conduct electricity.

17. Ionic Compounds
Compounds that contain ionic bonds are ionic compounds.
Salts, baking soda, and rust are examples of ionic compounds.
Ionic bonds are a force of attraction between oppositely charged ions.
Ions are charged particles and are formed when they gain (nonmetals) or lose (metals) electrons.

18. Ionic Compounds Properties
Brittle- Ionic compounds tend to shatter when hit
High Melting points- most ionic bonds don’t melt until they are very hot
Solubility- many ionic compounds tend to dissolve in water.
Water is a polar solvent and ionic compounds have positive and negative ends, which the water pulls on.

19. Covalent Bonding A sharing of electrons
The electrons are traveling somewhere in that blue bubble

20. Covalent Compounds Covalent compounds can be solids, liquids or gases
They don’t usually conduct electricity because they don’t have an overall charge

21. Covalent Compounds Covalent Compounds are made of molecules.
Molecules are atoms that share electrons in a bond.
Glass, rubbing alcohol, nitroglycerin, and natural gas are all covalent compounds.

22. Covalent Compounds Properties
Low melting points- several compounds exist as gases or liquids at room temperature.
Most covalent compounds do not dissolve in water or produce positive and negative particles if they do dissolve.
Therefore most covalent compounds do not conduct electricity by themselves.

23. Polarity Some atoms don’t share electrons equally
Sometimes the electron is more attracted to one side than the other causing the compound to be POLAR
If the electrons are shared equally they are said to be NONPOLAR COVALENT BONDS

24. Water and Conductivity
Pure water (highly polar) does not conduct electricity.
In order to conduct electricity, water must have positive and negative particles in it.
Dissolving ionic compounds puts positive and negative particles in the water increasing the conductivity of water.
Electrolyte- anything dissolved in water that increasing the conductivity
GATORADE

25. Metallic Bonding Bonds between metals
Both a sharing and a transfer of electrons
Metallic bonds only occur with the same metal not with other metals
Ca can bond with other Ca atoms, but not Ba

26. Metallic Bond
In metallic bonds the valence electrons become community property, traveling anywhere they want to throughout the element.
This “Sea of Electrons” is why metals are such good conductors of electricity and heat.

27. Model of Metallic Bonds
Calcium has 2 valence electrons Ca Ca
All of them
move like
this. Ca Ca Ca Ca
The “sea of electrons” is kind of like
bees (valence electrons) swarming
around a few hives (rest of the atom)

28. Metallic Bonds
Metallic Bonding is when all valence electrons are free to move from atom to atom.
A metallic bond only occurs between two of the same metal atom.
Copper can form a metallic bond with another copper atom but not with a gold atom.
Metals are flexible and can conduct electricity.

29. Polyatomic ions Some compounds have both covalent bonds and ionic bonds

30. Compound Names and Formulas
Chapter 6.3

31. Naming ionic compounds
For anions: anions gain electrons
For nonmetals only (the right side of the periodic table)
drop the ending and add “-ide”
so F-
fluoride
Cl-, O2-, C4-
chloride, oxide and carbide

32. Cations:
An Ion that has a positive charge because it gave an electron to another element
Examples: Litium ion
Potassium ion
Calcium ion

33. Continuing… Metals keep the name of the element.
When naming compounds always name the metal (cation) first and the nonmetal (anion) last.
so mixing ions of chlorine and sodium give you
sodium chloride
(metal) (nonmetal)

34. Determining the formula of ions
Ionic compounds are neutral (remember, they want to be happy so being neutral is most stable)
You need to find the lowest number of each ion to make it neutral
for example:
Na+ and O2-
2 sodium for every one oxygen
Na2O

35. Determining Charge (how do you do this?)
Remember everything in group 1 is +1
Everything in group 2 is + 2
Aluminum is + 3
Halogens (group 17) are -1
Oxygen group is -2
Nitrogen group is -3

36. Remember:
The number of valence electrons are the ones that want to react……
If you have fewer electrons you are likely to give up your electrons to something else (and then you become more positive)
If you have more electrons (but not 8, you will accept electrons easier, so become more negative)

37. More examples Al3+ and O2- K+ and Cl-
Al2O3
K+ and Cl-
KCl
the subscripts don’t effect the name if there is only one possibility
still (cation)(anion)
Aluminum oxide
Potassium chloride

38. Several metals can form a couple of different ions.
These are all metals that aren’t in group 1, 2 or aluminum.
For example iron can form Fe2+ or Fe3+
These are said as iron (II) and iron (III)
Cu+ and Cu2+ is Copper (I) and Copper (II)

39. Covalent naming
You still drop the ending of the second atom and replace it with the suffix “-ide”.
Ionic names ignored the subscript numbers.
Covalent does not.

40. Prefixes prefix meaning *mono- 1 hex- 6 di- 2 hept- 7 tri- 3 oct- 8
tetr- 4
non- 9
pent- 5
dec- 10
* the first atom named does not get the prefix
“mono-”, it just keeps its original name!

41. Examples CO CO2 NI3 P4O6 carbon monoxide carbon dioxide
nitrogen triiodide
P4O6
tetraphosphorus hexoxide

42. Continuing I4O9 S2F10 IF7 Si2Cl6 tetriodine nonoxide
disulfur decafluoride
IF7
Iodine heptafluoride
Si2Cl6
disilicon hexachloride