The Chemist’s Shorthand: Atomic
Symbols
- Element Symbols
- Neon
- Ne
- Chlorine
- Cl
- Nitrogen
- N
The Chemist’s Shorthand: Atomic
Symbols
- Oxygen
- O
- Silicon
- Si
- Zinc
- Zn
The Chemist’s Shorthand: Atomic
Symbols
- Gold
- Au
- Lead
- Pb
- Sodium
- Na
- Iron
- Fe
The Chemists’ Shorthand:
Formulas
Chemical Formula:
Symbols = types of atoms
Subscripts = relative numbers of atoms
CO2
Structural Formula:
Individual bonds are shown by lines.
O=C=O
The Chemists’ Shorthand:
Formulas
A molecule contains four phosphorus
atoms and ten oxygen atoms.
P4O10
A molecule contains one aluminum atom
and three chlorine atoms.
AlCl3
The Mass and Change of the
Electron, Proton, and Neutron
Particle
Mass (kg)
9.11  10
31
Proton
1.67  10
27
Neutron
1.67  1027
Electron
Charge
1
1+
0
The Chemists’ Shorthand: Atomic
Symbols
Mass number 
Atomic number 
39
K
19
 Element Symbol
Isotopes
Atoms with the same number of protons
but different numbers of neutrons.
K-39 and K-40
Na-23 and Na-24
H-1, H-2, and H-3
Periodic Table
Elements classified by:
properties
atomic number
Groups (vertical)
1A = alkali metals
2A = alkaline earth metals
7A = halogens
8A = noble gases
Periods (horizontal)
Periodic Table
Transition metals
Metals
Nonmetals
Semimetals (Metalloids)
Ions
Cation: A positive ion
Mg2+, NH4+
Anion: A negative ion
Cl, SO42
Ions
Mg2+
# of protons and electrons
12 protons and 10 electron
Mg -> Mg2+ + 2e-
Lost 2 electrons
Ions
K+
# of protons and electrons
19 protons
and 18 electron
K -> K+ + eLost 1 electron
Ions
Cl
# of protons and electrons
17 protons
and 18 electron
Cl + e- -> ClGained 1 electron
Ions
O2
# of protons and electrons
8 protons
and 10 electron
O + 2e- -> O2Gained 2 electrons
Writing Formulas for Ionic
Compounds
Ionic Compounds: Net Charge of Zero
1. Na+ and S2Na2S
2. Ca2+ and P3Ca3P2
Naming Compounds
Binary Ionic Compounds:
1. Cation first, then anion
2. Monatomic cation = name of the
element
Ca2+ = calcium ion
3. Monatomic anion = root + -ide
Cl = chloride
CaCl2 = calcium chloride
Naming Compounds
Binary Ionic Compounds:
NaCl
sodium chloride
AlF3
aluminum fluoride
MgBr2
magnesium bromide
Naming Compounds
Binary Ionic Compounds:
-
When metal forms more than one cation
use Roman numeral in name
PbCl2
Pb2+ is cation
PbCl2 = lead (II) chloride
Naming Compounds
Binary Ionic Compounds:
CuCl
copper(I) chloride
CuBr2
Copper(II) bromide
FeF3
iron(III) fluoride
Naming Compounds
Binary molecular compounds:
- Compounds between two nonmetals
- Second element is named as if it were
an anion.
- Use prefixes
- Never use mono- for the first element.
P2O5 = diphosphorus pentoxide
Naming Compounds
Binary compounds:
P2O5
diphosphorus pentoxide
CCl4
carbon tetrachloride
Naming Compounds
Binary compounds:
N 2O 3
dinitrogen trioxide
SCl6
sulfur hexachloride
Polyatomic Ions to Memorize
NO3–
Nitrate ion
NO2Nitrite ion
Polyatomic Ions to Memorize
SO42Sulfate ion
SO32Sulfite ion
Polyatomic Ions to Memorize
CO32Carbonate ion
HCO3bicarbonate or hydrogen carbonate ion
Polyatomic Ions to Memorize
PO43Phosphate ion
Polyatomic Ions to Memorize
NH4+
Ammonium ion
Compounds with Polyatomic
Ions
K2SO4
potassium sulfate
NaNO3
sodium nitrate
Compounds with Polyatomic
Ions
K2CO3
potassium carbonate
Na3PO4
sodium phosphate
Writing Formulas from Names
Disulfur dichloride
S2Cl2
Potassium oxide
K2O
calcium phosphate
Ca3(PO4)2
The Mole
The number equal to the number of
carbon atoms in exactly 12 grams of pure
12C.
1 mole of anything = 6.022  1023 units
of that thing
Avogadro’s number
equals
23
6.022  10 units
Molar Mass
•
A substance’s molar mass (molecular
weight) is the mass in grams of one mole of
the compound.
• CO2 = 12.0107 + 2 x 15.9994
• = 44.0095 grams per mole
Molar Mass
•
How many moles of CaCl2 are in a
10.0 g-sample of CaCl2? The molar mass of
CaCl2 is 110.98 g/mole.
• Moles = mass x (1/molar mass)
• = 10.0 g x (1 mole / 110.98 g)
• = 0.090106
• = 0.0901 mole (3 sig figs)
Molarity (M)
•
concentration expressed as moles of
solute per liter of solution.
• M = moles of solute/L of solution
• Moles of solute = Molarity (M) x L of
solution
• L of solution = moles of solute/Molarity (M)
Molarity (M)
•
Calculate the molarity of a solution
prepared by dissolving 65.5 g of solid NaCl in
enough water to make 4.50 L of solution.
• M = moles of solute/L of solution
• Moles of NaCl = mass x (1/molar mass)
• Molar mass of NaCl = 22.989770 + 35.453 =
58.443 g/mole
• Moles of NaCl = 65.5 g x (1 mole/58.443 g )
• = 1.12075 moles
• Molarity = 1.12075 moles/4.50 L = 0.249 M
Chemical Equations
Chemical change involves
a reorganization of the
atoms in one or more
substances.
Chemical Equation
A representation of a chemical reaction:
C2H5OH (l) + O2 (g)  CO2 (g) + H2O (g)
C2H5OH (l) +3O2 (g) 2CO2 (g) +3H2O (g)
reactants
products
To Balance a Chemical
Equation
Start with the most
complicated molecule.
Use the smallest integers for
the coefficients.
Never change the chemical
formula (subscripts)
Balance the following Chemical
Equation
Li(s) + Cl2 (g) -> LiCl(s)
2Li(s) + Cl2 (g) -> 2LiCl(s)
Balance the following Chemical
Equation
Ca(s) + HCl (aq) -> CaCl2 (aq) + H2(g)
Ca(s) + 2HCl (aq) -> CaCl2 (aq) + H2(g)
Balance the following Chemical
Equation
C12H22O11(s) + __O2(g) ->
__CO2(g) + __H2O(g)
C12H22O11(s) + 12O2(g) ->
12CO2(g) + 11H2O(g)