NAMING OF BINARY COMPOUNDS
Nomenclature: This is the system of naming chemical compounds. The system is called IUPAC (International union of pure and applied chemistry). The naming is determined by the constituent elements in the compound and the oxidation number if necessary.
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In naming binary compounds (compounds with only two elements), electropositive elements (cations) are usually named first while the electronegative elements (anions) come last with a modification of the name end with – ide.
Formula IUPAC name
MgO Magnesium oxide
H2S Hydrogen sulphide
NH4Cl Ammonium chloride
NaH Sodium hydride
But in cases where the two elements involved are non-metals, the above rule is not followed. For example, H2O (water) NH3 (ammonia) and PH3 (phosphine)
Name the following compounds: (a) NaCl (b) CaO (c) H2O2.
NAMING OF RADICALS AND COMPOUNDS HAVING ELEMENTS WITH VARIABLE OXIDATION NUMERS
Radicals (group of atoms of element carrying electrical charge) are treated as a single element when naming their compounds.
Examples of radicals with their names are as follows:
Radical IUPAC NAME
NH4+ Ammonium ion
OH‑ Hydroxyl ion
But in naming acid radicals, the oxidation number of elements is indicated by Roman numbers in bracket.
NO2‑ Dioxonitratei(iii) ion
NO3– Trioxonitrate(v) ion
CO32- Trioxocarbonate(iv) ion.
Also the compounds having elements with Roman numbers in bracket indicating their oxidation numbers in that compound
FeO Iron (ii) oxide
Cu2O Copper (i) oxide
MgCO3 Magnesium trioxocarbonate (iv)
- Name the following compounds (a) Fe2O3 (b) CuO
- What are the oxidation numbers of Fe and Cu in (1) above?
NAMING TERTIARY COMPOUNDS AND QUARTENARY COMPOUNDS.
These are compounds containing more than two elements.
Examples are oxo-acids, normal salts, and acid salts.
HNO3 Trioxonitrate(v) acid
H2SO4 Tetraoxosulphate (vi) acid
H3PO4 Tetraoxophospate (v) acid
Examples of Normal Salts.
Normal salts IUPAC
KNO3 Potassium trioxonitrate (iv)
NaSO4 Sodiumtetraoxosulphate (vi)
CuCO3 Copper (ii) trioxocarbonate (iv)
- Determine the oxidation number of: a) C in H2CO3 b) Mn in KMnO4 c) Cu in CuSO4
- Name the compounds in 1 above
NAMING OF COMPOUNDS WHOSE CATIONS HAS BEEN PARTIALLY REPLACED WITH HYDROGEN IONS.
In naming compounds whose cations have been partially replaced with hydrogen ion, the cations is named first followed by hydrogen, then the radicals present indicating the roman number standing for the oxidation number of the element that is combined with oxygen to form the radical.
E.g Formula IUPAC
NaHSO4 Sodium hydrogen tetraoxosulphate (vi)
KHSO3 Potassium hydrogen trioxosulphate (iv)
- Determine the following oxidation number of a) C in LiHCO3 b) S in KHSO4 and name the compounds
- Write the chemical formula of the following compounds a) Oxochlorate (I) acid b) Iron (ii) tetraoxosulphate (VI) pentahydrate
- State the uses of the following laboratory apparatuses a) Condenser b) Kipp’s apparatus c)Tripod stand.
- The compound Na2S is called ____ (a) Sodium (ii) sulphate (b) Sodium sulphur (c) Sodium sulphide (d) Sodium sulphite.
- The formula of sulphur (iv) oxide is (a) SO4 (b) SO2 (c) S2O4 (d) S4O2
- Ammonium chloride can be written as (a) NH4Cl (b) NH3Cl2 (c) NH4HCl (d) NH4OH
- The IUPAC name of NaHSO4 is (a) Sodium bicarbonate (b) Sodium tetraoxosulphate (vi) acid (c) Sodium sulphate (c) Sodium hydrogen tetraoxosulphate (vi)
- Which of the following compounds have cation with variable oxidation state. (a) FeO3 (b) ZnCO3 (c) CuO (d) KU
- Name the following compounds (a) Fe2O3 (b) KMnO4 (c) KClO3
- Calculate the oxidation number of (a) Sulphur in H2SO4 (b) Carbon in CuCO3