1. Chapter 3
FORMULAS AND NAMES!

2. Although there are only just over 100 elements, there are millions of different compounds!
Elements combine!
Only the noble gases tend to exist as isolated atoms (think noble = snobby)
Monatomic: consist of single atoms (mono = one)

3. Two main types
We talk about two main types of compounds. Classified by the BONDS they form!
IONIC COMPOUNDS: one element loses electrons, one gains. CHARGED IONS COME TOGETHER TO BE NEUTRAL. FORMED FROM IONIC BONDS
MOLECULAR COMPOUNDS: formed from COVALENT BONDS. Atoms SHARE electrons

4. Ions and Ionic Compounds
Ions: Atoms or groups of atoms with a positive or negative charge
This is where it’s important to know your valence electrons!
These are the outermost electrons of an atom
Use your periodic table to figure it out!
Group 1a has 1 valence electron
Group 8 has 8 valence electrons (ex is He=2)
Atoms want 8 valence electrons…so, will gain or lose!

5. Cation: ion with a positive charge (has lost an electron), generally groups 1a, 2a, 3a
Sodium, Na, Group 1a, 1 valence electron
Remember, atoms want to get to 8 valence electrons
Ask yourself: is it easier to lose 1 electron or gain 7?
Sodium will generally LOSE one electron= +1 charge
Na+1
What about Magnesium? Lithium?
What about Hydrogen?

6. For metallic elements, the name of the cation is the same as the name of the element
Sodium atom forms a sodium cation
Symbol = Na+1
Metals tend to have very different properties from their cations
Sodium metal is explosively reactive with water
Sodium cation is in table salt, stable in water

7. Anions
Anions: Atoms that have gained one or more electrons and have a NEGATIVE charge
Ex: Chlorine, group 7a, has 7 valence electrons
Ask yourself: is it easier to gain one electron or lose 7?
Gain 1= Cl-1
Chlorine Ion will gain one electron, -1 charge
The name of an ion usually ends in –ide
So a chlorine ion will be called chloride

8. Ionic Compounds
Ionic Compounds: Compounds made up of cations and anions
Usually composed of metal cations and nonmetal anions
Ionic compounds are electrically neutral
How Is this possible if they are made up of charged atoms???

9. Formula Units: lowest whole number ratio of ions in an IONIC COMPOUND
Think: metal and nonmetal!
Not a molecule. 3 dimensional patterns of ions
Think Salt NaCl

10. Writing Ionic Formulas! (Yay!!!!)
Ionic = METAL AND NONMETAL!
Ionic bond = swap of electrons
Metals lose, nonmetals gain, COMPOUND IS NEUTRAL!!!!!
Binary Ionic Compound : (2 elements)
1. Write the symbols
2. Find the charges (periodic table)
3. Criss-Cross
4. Reduce if necessary

11. Ternary Ionic Compounds: Compound that contains atoms of three different elements
Polyatomic Ions!
How to write the formula:
Write the Symbols
Surround the Polyatomic Ion in parentheses (think: PUT IT IN A BUBBLE)
Write charges
Criss Cross (charge goes OUTSIDE parentheses

12. Ionic Charges For monatomic ions, look at the periodic table
We know how to do this already!
For Transition metals, many have more than one charge! I have to give you the charge
Fe(II) ion (Read: “Iron two ion”)
Roman numeral gives you the charge

13. Polyatomic Ions Poly-many
Polyatomic ions: tightly bound groups of atoms that behave as a unit and carry a charge.
The names of most of the polyatomic ions end in ‘– ite’ or ‘-ate’ : sulfite (SO3- and SO4-)
Charge for each ion is the same, different numbers of O
TABLE ON THE BACK OF YOUR PERIODIC TABLE!!!

14. Naming Ionic Compounds
Binary:
1. Write the name of the metal (include roman numeral for transition metal)
2. Write the name of the nonmetal ending with –ide
Sodium Chloride, Iron (II) Oxide
Ternary:
Write the name of the cation (usually a metal, but ammonium (NH4) is a cation
Write the name of the anion (if polyatomic, just write the name on the chart, if nonmetal, end in – ide)
Naming Ionic Compounds

15. Molecular Compounds (AKA COVALENT)
Binary molecular compounds
2 NONMETALS
How can we tell the different compounds?
Prefixes!!!
To Name a Molecular compound:
Use prefixes to tell me how many of each atom
Name end in –ide
CO= carbon monoxide
CO2= carbon dioxide
You can leave the ‘mono’ off of the first element, but not the second

16. Molecular compounds: compounds composed of molecules.
Generally 2 nonmetals
Most have low melting or boiling points so most exist in liquid or gas state at room temperature
Carbon Monoxide
Carbon Dioxide
Dihydrogen Monoxide
(see a pattern in naming? We’ll get to that later…)

17. Molecular Formulas YAY!!!!
Molecular compounds involve electron SHARING
But… they can share in multiple ways!
Think of CO and CO2 = both would be named carbon oxide if we used ionic rules
Molecular compounds = TWO NONMETALS
How can you tell two molecular compounds apart? PREFIXES

18. Know Your Prefixes!!! Mono = 1 Octa = 8 Di = 2 Nona = 9 Tri = 3
Deca = 10
Tetra = 4
Penta = 5
You must know these prefixes for the test! I will not give them to you
Hexa = 6
Hepta = 7

19. So, to write the formula of a molecular compound, just decode the prefixes
Dihydrogen monoxide
Di = 2 hydrogen
Mono = 1 oxygen
Formula is H2O

20. Exceptions:
If there is only one atom of the first element, you don’t need the prefix ‘mono’ (still need it for the second element, though)
If the element starts with a vowel, drop the 2nd ‘o’ on ‘mono’
Monoxide, not monooxide

21. Naming Molecular Compounds
Use prefixes to indicate number of atoms
End second element in ‘-ide’
Example:
OF2 = oxygen difluoride (no ‘mono’ on first element)
Cl2O8 = dichlorine octaoxide

22. Just use the prefixes to tell you how many of each atom!
Molecular formulas
Just use the prefixes to tell you how many of each atom!
Carbon tetrafluoride = CF4
Dihydrogen monoxide = H2O

23. Ionic : metal and nonmetal, get charges and criss cross, NO prefixes
The tricky part!!!
Ionic : metal and nonmetal, get charges and criss cross, NO prefixes
Molecular: two nonmetals, no charges, use PREFIXES

24. Naming Acids
Acids are compounds that release H1+ ions when dissolved in water.
Look for compounds with a ‘hydrogen’ in it
Technically a molecular compound, but….

25. Naming Acids Name using ionic rules
If ends in ‘-ide’, add ‘hydro’ to the beginning and ‘-ic acid’ to end
If ends in ‘-ite’, add ‘-ous acid’ to the end
If it ends in ‘ate’, add ‘-ic acid’ to the end

26. HCl
Hydrogen chloride
Hydrochloric acid
H2SO3
Hydrogen sulfite
Sulfurous Acid
H2SO4
Hydrogen sulfate
Sulfuric Acid

27. Aight, it’s us (ite => ous) I ate something ick! (ate => ic)
THINK!
Aight, it’s us (ite => ous)
I ate something ick! (ate => ic)

28. More with the MOLE!
Would it be practical to count each grain of sand? Why or why not?
You can measure matter by number, mass, or volume
We have units that measure the amount of something: dozen=12
Mole (mol): SI unit that measures amount
6.02 x 1023 representative particles of something (usually atoms, molecules or formula units)

29. Representative Particles and Moles
Substance Representative Particle Chemical Formula # particles in one mole
Atomic Nitrogen Atom N x 1023
Nitrogen Gas Molecule N x 1023
Water Molecule H2O x 1023
Calcium Ion Ion Ca x 1023
Calcium Fluoride formula unit CaF x 1023
Sucrose Molecule C12H22O x 1023

30. Atom to Mole Conversions
Since it is much easier to refer to a quantity of atoms/representative units instead of a singular atom/representative unit, we can convert # of atoms to MOLES and moles to # of atoms!
1. Start with your known
2. Use a conversion factor
3. What you want goes on the TOP!
4. LABEL EVERYTHING!!!

31. Let’s TRY it!
How many moles of magnesium is 1.25 x 1023 atoms of magnesium?
1. Start with your known: 1.25 x 1023 atoms of magnesium
2. use a conversion factor: 1 mol Mg/ 6.02 x 1023 atoms of Mg
3. What you WANT goes on TOP
1.25 x 1023 atoms of magnesium x 1 mol Mg/ 6.02 x 1023 atoms of Mg

32. More Practice: How many moles is 2.80 x 10 24 atoms of silicon?
How many molecules is mol of water?

33. Atoms in a Mole of a Compound
You can also calculate the number of atoms in a mole of a compound
Same steps, just do it twice!
Moles => representative unit => atoms

34. Lets Try it! How many atoms are in 2.12 mol of propane (C3H8)?
Moles => molecules =>atoms (2 calculations!)
2.12 mol C3H8 x 6.02 x 1023 molecules C3H8/1 mol C3H8
How many atoms in one molecule of C3H8???
3 carbons + 8 hydrogens = 11 total atoms
1.27 x 1024 molecules of C3H8 x 11 atoms / 1 molecule C3H8
Answer is 1.40 x 1025 atoms

35. More Practice! 1. How many atoms in 1.14 mol of SO3?
2. How many atoms of C, H, and O are in 3.65 moles of C12H22O11?

36. The mass of a Mole of an Element
Think of the bag of sand. Would it be easier to work with mass or the number of sand particles? Mass is EASIER!
Gram atomic mass (gam): the atomic mass of an element expressed in grams
This is the atomic mass from the periodic table rounded to one decimal place.
Carbon = Chlorine = 35.5
The gram atomic mass of any element contains 1 mole of atoms!!!!!! (this is where 6.02 x 1023 comes from)

37. The mass of a Mole of a Compound
The gram molecular mass (gmm) of any molecular compound is the mass of 1 mol of the compound
JUST ADD UP THE MASSES!
Ex. Water = H2O
Gmm = mass of hydrogen + mass of hydrogen + mass of oxygen= = 18 g = 1 mol of water

38. Gram Formula Mass: (gfm) the mass of one mole of an ionic comound
Find it the same way, just ADD IT UP!
What is the gfm of NaCl?
Na = 23.0 Cl= 35.5
= 58.5 g = 1 mol of NaCl

39. Percent composition and Chemical Formulas
You already know how to calculate percent composition
Percent composition =
Mass of element/mass of compound x 100
To check: percentages should add up to 100%
If no mass is given, PERIODIC TABLE!

40. Calculating Empirical Formulas
Empirical Formula: the lowest whole-number ratio of the atoms of the elements in a compound.
To calculate the empirical formula from experimental data:
Calculate the moles of each element in the compound
Identify the smallest mole value
Divide all mole values by this smallest number
This should give you a whole number (this is a comparative ratio!)

41. Molecular Formulas
You can determine the molecular formula if you know the empirical formula and the molar mass of the unknown compound
Just take molecular mass/empirical mass. This will give you a whole number by which to multiply the subscripts!

42. Formulas from Combustion Analysis
1. Write down the masses of each combustion product and the mass of the sample (if given) 2. Convert the masses of CO2 and H2O to moles 3. Convert the moles of CO2 and H2O to moles of C and H 4. If the compound contains and element other than C and H, find the mass of the other element by subtracting the sum of the masses of C and H from the mass of the sample. Convert this mass to moles 5. Write down temp. formula (moles = subscript) 6. Divide each subscript by the smallest number 7. If not whole number subscripts, multiply to get a whole number

43. Chemical Reactions
In a chemical reaction, one or more substances changes into one or more different substances.
Reactants -> Products
-> is read as ‘yields’

44. As reactants are converted to products, the bonds holding the atoms together are broken and new bonds are formed.
Law of conservation of mass applies here! Although bonds are broken and reformed, the atoms are neither created nor destroyed.
How can you tell a reaction has occurred?
Formation of gas(bubbles), heat is given off or absorbed(hot or cold), or formation of a precipitate (floaty stuff)

45. Chemical Equations
We use formulas to write chemical equations to describe reactions
Skeleton equation: unbalanced formula
To indicate the physical state of the substance: (s) is solid, (l) is liquid, (g) is gas, and (aq) is aqueous solution (disolved in water)
Catalyst: used to speed up a reaction, but not used up during the reaction. Written on top of the ‘yields arrow’
Heat can also be used to produce a reaction and is indicated above the arrow

46. Some elements always occur in pairs if in a pure state. HONClBrIF
Diatomic elements
Some elements always occur in pairs if in a pure state.
HONClBrIF
H2 O2 N2 Cl2 Br2 I2 F2

47. Balancing Equations RULES
1. Write the correct formulas for the products/reactants and their physical states (if known)
2. Reactants on left, products on right, separated by ‘yields arrow’
3. Balance the elements one at a time by using a coefficient
4. Make sure coefficients can’t be reduced

48. Word Equations You can write an equation from a word description!
You MUST KNOW YOUR FORMULAS!
1. Write the formulas for the reactants (watch for diatomics!!!)
2. Write a ‘yield arrow’
3. Write the formulas for the products (watch for diatomics!
4. Balance the equation!!!!!

49. Types of Chemical Reactions
5 main types
Synthesis (combination), Decomposition, Single Replacement, Double Replacement, Combustion
Combination Reactions: (also called SYNTHESIS reactions, synthesis=make something)
A + B => AB
(look for one product)

50. Decomposition reactions
Decomposition reactions are when a compound breaks down into simpler compounds/elements
Decomposition means TO BREAK DOWN
AB => A + B
Look for one REACTANT
Most require some sort of energy input

51. Single Replacement Reactions
In single replacement reactions, one element replaces another element in a compound.
A + BC => AC + B
Metal will replace metal, nonmetal will replace nonmetal
Depends on the reactivity of the element
Activity Series: lists elements in order of reactivity. More reactive elements will replace less reactive elements.

52. Double Replacement Reactions
Double replacement reactions involve an exchange of positive ions between two ionic compounds.
The metals switch places
AB + CD => AD + CB
When rewriting the new compounds, metals still come first!

53. Combustion Reactions
Combustion reactions occur when a compound reacts with oxygen to produce carbon dioxide and water.
Often produces heat and light (burning)
Equation will always be the same (only the starting compound will change)
Compound + O2 => CO2 + H2O