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Chapter 9. Chemical Names and Formulas. Copper Compounds. What is the difference between Cu 2 O and CuO ? Is there any difference? - PowerPoint PPT Presentation
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Chapter 9Chemical Names and Formulas
What is the difference between Cu2O and CuO? Is there any difference? You may think that there is very little difference
between the two, but there is! Naming compounds very specifically is important in order to tell the difference between similar compounds?
Cu2O Red powder fungicide
CuO Black powder Used in batteries
Copper Compounds
What is a cation? Cations – positively charged ion
How many electrons does Group1,2, and 3 lose? Groups 1,2, and 3 lose electrons
Group 1 – lose 1 electron Group 2 – lose 2 electrons Group 3 – lose 3 electrons
Remeber Naming Ions?
Anion – negatively charged ion Groups 5,6, and 7 generally gain electrons
Group 5 – gain 3 electrons Group 6 – gain 2 electrons Group 7 – gain 1 electron
Remember Naming Ions?
Transition metals usually lose electrons, how many electrons they lose depends on the element
Naming Ions
If you actually think about it, it will make sense why some of the transition elements could have two different ions
Ex: Copper (Cu) forms both a +1 and a +2 cation
Why? (Hint: Use the periodic table and electron configuration.) +1 cation: Cu = [Ar] 4s1 3d10 – loses 1 from the
4s subshell + 2 cation: if Cu does not achieve pseudo-
stability, it is [Ar] 4s2 3d9 – will lose the two electrons from the 4s subshell
Naming Ions
Ions composed of more than 1 atom You just have to memorize these Most end in –ite or –ate -ite tells you there is 1 less oxygen
atom than the –ate ending
Polyatomic Ions
what do ionic compounds contain? Ionic compounds – contain a metal and a
nonmetal How do we name a binary ionic compound
(binary means composed of 2 elements)? Place the cation name first, then the anion name Usually add –ide to the end of the anion name
Naming and Writing Formulas for Ionic Compounds
What would Cs2O be? Cesium oxide
NaF? Sodium fluoride
Cu2O (hint: copper has two possible ions! Which one is it?) Copper (I) oxide
SnS2
Tin (IV) Sulfide Mn2O3
Manganese (III) oxide LiCN
Lithium cyanide (NH4)2C2O4
Ammonium oxalate (the –ide ending is usually left out if the anion is a polyatomic ion)
Naming and Writing Formulas for Ionic Compounds
To write a formula for a binary ionic compound, we need to go back to Ch. 7 and balance the charges
Ex: iron (III) oxide Fe+3 O-2
Fe2O3
Ca+2 S-2
Ca2S2….reduce to CaS
Remember crisscross the charge and reduce subscripts to the lowest whole number ratio
Naming and Writing Formulas for Ionic Compounds
Another way…just think about how you would balance the charges out by finding the least common multiple
K+1 N-3
We need a 3 to balance out the +1 on K (1 x 3 =3) and a 1 to balance out the -3 on N (1 x 3) = 3
So K3N
Ba+2 S-2
Both have a 2 charge, they balance each other out
BaS
Naming and Writing Formulas for Ionic Compounds
For polyatomic ions, keep the ion together – balance the overall charge of the ion
Ex: Ca+2 (NO3)-1
Ca(NO3)2
Use parentheses to set off the polyatomic ion only if there is than one of the polyatomic ion
Ex: Li+1 (CO3)-2
Li2CO3 – no parentheses because there is only one polyatomic ion
Ex: NH4+1 (SO3)-2
(NH4)2SO3
Naming and Writing Formulas for Ionic Compounds
What is a binary molecular compound? A compound composed of 2 elements that are
both nonmetals – NOT ions Binary compounds can have 2 elements
composed in various ways – ex: CO and CO2 or NO and N2O so we can’t name them like we did with ionic compounds
We need prefixes…prefixes tell us how many atoms of each element are present in each molecule
Naming and Writing Formulas for Molecular Compounds
Here are a few hints: If there is only 1 atom of the first element, omit the
prefix mono- You will usually add the –ide ending to the second
element Ex: CO
Carbon monoxide Ex: N2O
Dinitrogen monoxide Ex: Cl2O7
Dichlorine heptoxide Ex: BCl3
Boron trichloride
Naming and Writing Formulas for Molecular Compounds
Use the prefixes of each element to write the formula (hint: -mono is left out of the first element if there is only 1 atom)
Ex: carbon monoxide CO
Ex: carbon tetrabromide CBr4
Ex: diphosphorus trioxide P2O3
Ex: iodine heptafluoride IF7
Naming and Writing Formulas for Molecular Compounds
Compound
Covalent
nonmetals
Use prefixes + ide Omit “mono”
for first element if
there is only one
IonicMetal + nonmetal
Cation has one charge
Metal + nonmetal
+ ide ending
Cation has more than 1
chargeMetal (charge) + nonmetal +
ide ending
Summarization