Review of Sec IV Chemistry. Ions An ion is an atom that has become electrically charged by losing or...
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Transcript of Review of Sec IV Chemistry. Ions An ion is an atom that has become electrically charged by losing or...
Review of Sec IV Chemistry
Ions
• An ion is an atom that has become electrically charged by losing or gaining one or more electrons
Most Probable Ions for Group A Elements
IA IIA IIIA IVA VA VIA VIIA VIIIA
E+ E2+ E3+
E4+
Or
E4-
E3- E2- E1- None
Li+ Be2+ B+
C4+
Or
C4-
N3- O2- F- --
Gro
up #
Mos
t P
rob
able
F
orm
of
Ion
Exa
mpl
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Polyatomic Ions
• A group of two or more chemically bonded atoms that has become electrically charge by losing or gaining one or more electrons
Chemical Formula Name
CH3COO- Acetate
NH4+ Ammonium
HCO3- Bicarbonate
CO32- Carbonate
CIO3- Chlorate
CrO42- Chromate
OH- Hydroxide
NO3- Nitrate
NO2- Nitrite
PO43- Phosphate
SO42- Sulphate
SO32- Sulphite
Rules of Chemical Notation
1. Find the symbol of each element in the molecule on the periodic table
2. Determine the order of the symbols: In binary molecules containing a metal and a nonmetal, the metal comes first. In all other cases the order is: B, Ge, Si, C, Sb, As, P, N, H, Te, Se, S, I, Br, O and F
3. Add subscripts after the symbols to specify the # of atoms or ions of each elements in the molecule
• To know the subscript the number of the atoms in the molecule must be adjusted so that each atom forms all the bonds to balance their charges
Nomenclature
1. Name the first element
2. Change the name of the second element according to the indication in the following table
3. When applicable, a prefix or prefixes is added to specify the # or atoms of each elements
Some Names for the 2nd Element in a Binary MoleculeName: Nomenclature:
Bromine Bromide
Carbon Carbide
Chlorine Chloride
Fluorine Fluoride
Hydrogen Hydride
Iodine Iodide
Nitrogen Nitride
Oxygen Oxide
Phosphorus Phosphide
Sulphur Sulphide
Prefixes for the # of Atoms
Number of Atoms: Prefix:1 Mono-2 Di-3 Tri-4 Tetra-5
Penta- 6 Hexa-7
Hepta- 8 Octa-9 Nona-10 Deca-
New Stuff: Limiting Reagent
• Any reactant that is used up first in a chemical reaction; it determines the amount of product that can be formed in the reaction
Cookin’ with Chem
• Limiting Reagent is like cooking something but have only a certain amount of ingredients
• If you were making sandwiches and had a full jar of peanut butter and a full jar of jam but only 6 slices of bread, the bread is limiting how many sandwiches you can make
3H2 + N2 → 2 NH3
Microscopic Recipe:
3 molecules H2 + 1 molecule N2 → 2 molecules NH3
Macroscopic Recipe:
3 mol H2 + 1 mol N2 → 2 mol NH3
Before:• Hydrogen and nitrogen are present
in a 3:2 molecule (mole) ratio.
• The reaction takes place according to the balanced equation where 3 molecules (moles) of H2 react with 1 molecule (mole) of N2
• At this point all the hydrogen is used up
After:
• Since all the hydrogen is gone, no more reacting can happen BUT there is still 1 molecule (mole) of un-reacted Nitrogen left
• There is also now 2 molecules (moles) of NH3
So…..
• For this reaction the Hydrogen is the limiting reagent
• We call the Nitrogen the excess reagent, which is the reactant that there is more than enough of to react with the limiting reagent in a reaction