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Compounds
Pure substances that are composed of 2 or more elements chemically combined in fixed proportions
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Covalent compounds
Formed by 2 or more different non-metals (only)
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Binary covalent compounds
Contain just 2 different NM's
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Inorganic covalent compounds
No carbon
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Formula structure rules for covalent compounds
- 1. More metallic NM leads formula
- 2. # of each NM become subscripts in formula
- 3. Names of 2 NM's are in compound name
- -1st element = name unchanged
- -2nd element = ending changed to -IDE
- - extra rule on lab notes
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Ionic compounds
Formed by chemical combination of metals with non metals in fixed proportions
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Metals
Are always + because the always lose e- (cation)
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Nonmetals
Are always - because they always gain e- (anion)
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NM Anions (monatomic)
- Group 7A: -1 charge
- Group 6A: -2 charge
- Group 5A: -3 charge
- Group 4A: -4 charge
- Exception: Group 8A = noble gasses and they don't give or take e-
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Metals cations (monatomic)
Are always + because the lose e- in ionic compounds
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Main group metals "A"
- Group 1A: All +1
- Group 2A: All +2
Group 3A: -
Al +3-
Ga +3- In +3/+1
Ti +3/+1- Group 4A:
Sn +4/+1 Pb +4/+1 - Group 5A: Bi +5/+3
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Transition Metals "B"
- TM's that form 2 or more cation
- Chromium: Cr+2, Cr+3, Cr+6
- TM's that form one cation
- Zn+2, Cd+2, Ag+1Look at nomenclature lab for the rest 12
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Naming metal cations
The names are the same as the original element names but, if a metal can form more that one cation then you use Roman numerals in parenthese.
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Formulas and Names of Ionic Compounds
- - Cations lead the formula and the name
- - COmbine cations and anions in simple whole # ratios. The rations become subscripts i the formula
- - Prefixes never used for ionic compounds
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