Compound: are substances that are composed of two or more elements in fixed proportions. Ex: H2O, CO2, NaCl…
Organic Compound:Compounds of carbon are called as organic compounds.
Inorganic Compound: All compounds other than organic ones are named inorganic.
Oxides are binary compounds of oxygen with metals and non-metals. (Ex: Na2O , N2O5 etc.)
Acids are compounds those are made up of hydrogen and an acidic remnant. (Ex: HCl, H2SO4 etc.)
Bases are compounds those are made up of hydroxide (OH) and metals. (Ex: NaOH, Ca(OH)2 etc.)
Salts are compounds those are made up of metal and acidic remnant. (Ex: NaCl, CaSO4 etc.)
OXIDES
The compounds of oxygen with another element are called oxides.
There are only two kinds of atoms in oxides. Na2O, CaO, Fe2O3, CO, SO2, OF2 and H2O2 are examples of oxides.
CaCO3, HClO2, C2H5OH are not oxides. Although they contain oxygen, they also have a third kind of atom.
Ex: Determine that the following compounds are oxide or not?
CO2, H2O, HCl, H3PO4, NO, H2CO3, N2O5, P2O5
Nomenclature of oxides:
If you are trying to name a metal oxide, just use the name of the metal and add oxide.
MgO: Magnesium oxide
Na2O: Sodium oxide
CaO: Calcium oxide
However, for example we know that iron (Fe) has two different valences II and III .So, to distinguish these iron oxides; we should also write the valences of these elements after their names.
FeO: Iron (II) oxide
Fe2O3: Iron (III) oxide
When naming a non-metal oxide, you should know some numbers in Latin.
1: mono, 2: di, 3: tri, 4: tetra, 5: penta then,
N2O3 : Dinitrogen trioxide
P2O5: Diphosphorus pentoxide (not pentaoxide)
CO2: Carbon dioxide (not mono carbon dioxide)
CO: Carbon monoxide (not monocarbon monoxide)
Ex: Name the following oxides: MgO, NO2, Al2O3, CO2, K2O
Ex: The oxide of a group 1A metal contains 25.8% oxygen by mass. Find this metal (answer: Na)
Ex: The oxide of a group 2A metal contains 28.6% oxygen by mass. Find this metal.
Classification of Oxides
1. Acidic Oxides
Acidic oxides are oxygen rich non-metal oxides.
CO2, SO2, SO3, NO2, N2O3, N2O5, P2O5, Cl2O7 are some examples of them.
Chemical Properties of Acidic Oxides:
- They react with water to give acids.
N2O5+H2O ® 2HNO3 Nitric acid
SO3+H2O ® H2SO4 Sulfuric acid
- They react with bases give salts (and water)
SO3 + 2KOH ® K2SO4+H2O
Acidic oxide Base Potassium sulfate (salt)
CO2 + 2NaOH ® Na2CO3+H2O
Acidic oxide Base Sodium carbonate (salt)
2. Basic Oxides
Compounds of most metals with oxygen are basic oxides.
Na2O, K2O, CaO, MgO, FeO, and CuO are examples to basic oxides.
Chemical Properties of Basic Oxides:
- Basic oxides react with water to give bases.
Na2O+H2O ® 2NaOH Sodium hydroxide
CaO+H2O ® Ca(OH)2 Calcium hydroxide
- Basic oxides react with acids and acidic oxides to give salts (and water).
Na2O + 2HCl ® 2NaCl+H2O
Basic oxide Acid Sodium chloride (salt)
MgO + 2HNO3 ® Mg(NO3)2+H2O
Basic oxide Acid Magnesium nitrate (salt)
Na2O + SO3 ® Na2SO4
Basic oxide Acidic oxide Sodium sulfate(salt)
3. Neutral Oxides
These oxides are oxygen poor non-metal oxides.
N2O, NO and CO are examples for neutral oxides (number of oxygen is equal or lower than number of non-metal).
These have neither acidic nor basic properties. Therefore, they do not give any reaction with any of them.
4. Amphoteric Oxides
An Amphoteric substance is one which has both acidic and basic properties. Under different experimental conditions, such substances can behave as a weak base or weak acid.
BeO-SnO-ZnO-PbO-Al2O3-Cr2O3 are examples of amphoteric oxides.
The Most Important Oxide: Water
- Water is the most common and the most essential oxide.
- 75% of the earth surface, 65% of human body, about 60% of the trees is water.
- Oceans (more than 97% water) helps establishment of heat balance of earth.
- Water cools automobile engines and nuclear power plants.
- Water is also used in industry. For example, it is needed for production of steel and paper.
Physical properties:
- Pure water is colorless and tasteless.
- It boils at 100 oC and freezes at 0 oC under 1 atmospheric pressure (at seaside).
- Its density is highest at 4 oC and is equal to 1g/cm3. So its density decreases and volume increases when it freezes. Water is the only substance whose density is lower when it freezes. This property of water makes possible life in seas in winter.
Chemical Properties of Water:
- Water reacts with active metals (Li, K, Ba, Ca and Na) to give bases of these metals and hydrogen gas.
2Na+2H2O ® 2NaOH+H2
Ca+2H2O ® Ca(OH)2+H2
- Water reacts with basic oxides to produce bases.
Na2O+H2O ® 2NaOH Sodium hydroxide
CaO+H2O ® Ca(OH)2 Calcium hydroxide
- Water reacts with acidic oxides to produce acids.
CO2+H2O ® H2CO3 Carbonic acid
SO3+H2O ® H2SO3 Sulfuric acid
- Water decomposes by the effect of high temperature (above 2000 oC) or constant electric current.
2H2O ® 2H2 + O2
ACIDS
Acids are complex substances those are composed of hydrogen and acid radical.
Ex: HCl; H2CO3; H3PO4 (Cl-CO3-PO4 are acid radical)
The Naming of Acids
FORMULA |
NAME |
HCl |
HYDROCHLORIC ACID |
HI |
HYDROIODIC ACID |
HF |
HYDROFLUORIC ACID |
H2S |
HYDROSULFURIC ACID |
H2SO4 |
SULFURIC ACID |
H2SO3 |
SULFUROUS ACID |
HNO3 |
NITRIC ACID |
HNO2 |
NITROUS ACID |
The Classification of Acids According to the Number of Hydrogen Atoms
Different acids may produce one, two or three H+ ions per molecule in their aqueous solutions. According to the number of H+ ions produced, acids are classified as monoprotic, diprotic or triprotic.
Obtaining of Acids
Many oxygen containing acids can be obtained from the reactions of acidic oxides with water.
SO3 + H2O à H2SO4
CO2 + H2O à H2CO3
CHEMICAL PROPERTIES OF ACIDS
1. Acids act as an indicator:
Indicators are substances that change their color by the effect of acids or bases.
Litmus paper and methyl orange are two important examples of indicators.
Litmus paper à red in acids
Methyl orange à red in acids
Phenolphthalein à colorless in acids
2. Acids react with metals:
Acids react with give displacement reactions with the metals that are more active than hydrogen.
Activity order of metals:
Li-K-Ba-Ca-Na-Mg-Al-Mn-Zn-Fe-N-Sn-Pb-H2-Cu-Hg-Ag-Pt-Au
MORE ACTIVE à LESS ACTIVE
2HCl + Mg à MgCl2 + H2
H2SO4 + Zn à ZnSO4 + H2
Cu + HCl à NO RXN
3. Acids react with basic oxides:
Acids react with basic oxides to give water and salt.
2HCl + Na2O à 2NaCl + H2O
4. Acids react with bases:
Acid + Base à Salt + Water
HCl + NaOH à NaCl + H2O
H2SO4 + 2KOH à K2SO4 + 2H2O
HYDROCHLORIC ACID- HCl
- HCl is one of the most important acids.
- HCl is gaseous state and has a sharp smell.
- It acts as an indicator, reacts with metals to produce H2 gas and reacts with bases to give salt and water.
- Presence of HCl can be understood by addition of AgNO3. Silver nitrate produces a white precipitate with HCl.
HCl + AgNO3 à AgCl + HNO3
BASES
Compounds of metals (except amphotheric metals: Al, Sn, Zn, Pb, and Cr) with hydroxide (OH) are called bases.
Ex: KOH, Ca(OH)2…
Nomenclature of Bases: To name a base just say the name of metal and hydroxide. Indicate the valency of metal if it can take more than one valencies.
Ca(OH)2 :Calcium hydroxide
NaOH : Sodium hydroxide
Mg(OH)2 :Magnesium hydroxide
Fe(OH)2 :Iron (II) hydroxide
Fe(OH)3 :Iron (III) hydroxide
Classification of Bases: Some of the bases are soluble in water but some of them are not. Water-soluble bases are also called alkalis. Magnesium hydroxide is not soluble in water so it is not an alkali; but sodium hydroxide and barium hydroxide are alkalis.
Obtaining Bases: Bases can be obtained from the reactions of active metals with water. For example:
Ba + 2H2O ® Ba(OH)2 + 2H2
2Na+ 2H2O ® 2NaOH + H2
Bases can also be obtained from the reactions of basic oxides with water:
BaO+H2O®Ba(OH)2
Na2O+H2O®2NaOH
Chemical Properties of Bases:
1) Bases Act on Indicators: Alkali’s change the color of indicators. In the basic solutions; the color of red litmus paper turns to blue; the color phenolphthalein turns to violet and the color of methyl orange turns to yellow.
!!! Only water-soluble bases can change the colors of the indicators. Water insoluble bases do not have any effect on indicators.
2) Bases React with the Acids: All bases react with acids to give salt and water.
NaOH + HCl ® NaCl + H2O
Mg(OH)2 + 2HCl ® MgCl2 + 2H2O
3) Alkali’s React with Acidic Oxides: Alkali’s react with acidic oxides to produce salt and water. However, water insoluble bases do not react with the acidic oxides.
Ca(OH)2 + CO2 ®CaCO3 + H2O
2NaOH + N2O5 ®2NaNO3+ H2O
4) Decomposition Reactions: When heated, water insoluble bases decompose to give metal oxides and water. However, water-soluble bases do not decompose.
Cu (OH)2 t CuO + H2O
KOH t No reaction
Amphotheric hydroxides: The compounds of amphotheric metals with hydroxide are amphotheric hydroxides. Similar to amphotheric oxides, these compounds can react with both acids and bases.
Zn(OH)2+ 2HCl®ZnCl2+2H2O
Zn(OH)2+ 2NaOH®Na2ZnO2+2H2O
Amphoteric oxide |
Basic form of hydroxide |
Acidic form of hydroxide |
BeO |
Be(OH)2 |
H2BeO2 |
SnO |
Sn(OH)2 |
H2SnO2 |
ZnO |
Zn(OH)2 |
H2ZnO2 |
PbO |
Pb(OH)2 |
H2PbO2 |
Al2O3 |
Al(OH)3 |
HAlO2 (H3AlO3) |
Cr2O3 |
Cr(OH)3 |
HCrO2 (H3CrO3) |
SALTS
Compounds of metals with acid radicals are called salts.
Ex:NaCl, K2SO4, BaCl2…
Nomenclature of Salts:
Salt name= metal name + name of acid radical
NaCl: sodium chloride
BaSO4: barium sulfate
FeCl2: iron (II) chloride
FeCl3: iron (III) chloride
Chemical Properties of Salts
1. Reaction with metals: metals can react with the salts of less active metals. (Activity of metal should be less than salt.)
Cu + 2AgNO3 à Cu(NO3)2 + 2Ag Cu is less active than Zn
Ag +Cu(NO3)2 à no rxn
2. Reaction with alkalies:
Ba(OH)2 + Na2SO4 à BaSO4 (insoluble) + 2NaOH
KOH + Mg(NO3)2 à KNO3 + Mg(OH)2 (insoluble)
KOH + NaCl à KCl + NaOH (NaCl, NaOH, KOH, and KCl are all soluble in water, so there will be no net reaction. They will all remain as ions in water.)
3. Reaction with acids:
- Formation of a precipitate:
AgNO3 + HCl à AgCl precipitate + HNO3
- Formation of weak acid
Mg3(PO4)2 + 3 H2SO4 à 3MgSO4 + 2H3PO4 acid
4. Reaction with another salt: two water soluble salts may react to give two different salts.
AgNO3 + NaCl à AgCl + NaNO3