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Basic of Elements,ions, compounds and valency

lement Symbol

Element Name

Element Symbol

Element Name

HHydrogenMnManganese
HeHeliumFeIron
LiLithiumCoCobalt
CCarbonNiNickel
NNitrogenCuCopper
OOxygenZnZinc
FFluorineBrBromine
NeNeonAgSilver
NaSodiumSnTin
MgMagnesiumIIodine
AlAluminiumBaBarium
SiSiliconWTungsten
PPhosphorusPtPlatinum
SSulphur / SulfurAuGold
ClChlorineHgMercury
ArArgonPbLead
KPotassiumCrChromium
CaCalciumTiTitanium
PuPlutoniumUUranium

NAMING COMPOUNDS

PREFIX OR
SUFFIX

MEANING

EXAMPLE

Mono-There is 1 atom of that type in that moleculeCarbon monoxide (CO)
Di-There are 2 atoms of that type in the moleculeCarbon dioxide (CO2)
Bi-Hydrogen is present in the moleculeSodium bicarbonate

(NaHCO3)

-ideThere are only 2 types of atoms present in the moleculeLead oxide

(PbO)

-ateThere are 3 or more types of atoms in the molecule, and 1 type is oxygenCalcium carbonate

(CaCO3)


VALENCY TABLE

  • Valency - the charge of an ion or radical which has either lost or gained electrons
  • Note that metals lose electrons easily to become positive ions. This is why most metals are good conductors of electricity.

1+

2+

3+

1-

2-

3-

1+Mg 2+Al 3+1-2-

oxide

PO4 3-

phosphate

Na 1+Ca 2+Fe 3+

ferric

Cl 1-2-

sulphide

 
Li 1+Cu 2+ Br 1-CO3 2-

carbonate

 
1+Zn 2+ OH 1-

hydroxide

SO4 2-

sulphate

 
Ag 1+Pb 2+ NO3 1-

nitrate

  
NH4 1+

ammonium

Fe 2+

ferrous

 HCO3 1-

bicarbonate

  

WORKING OUT FORMULAE OF IONIC COMPOUNDS
(THE CROSS-OVER METHOD)

  • Step 1 - In the ionic compounds to be learnt in junior science, there are two parts to the ionic compound - the first is a positive ion (usually a metal e.g. Na1+) and the second is a negative ion (e.g. Cl1-).
  • Step 2 - Using the valency table, write the two ions and their valencies.
  • Step 3 - Now ignore the positive and negative signs. Cross-over the top valency number to the bottom of the other ion symbol. Do this for both.
  • Step 4 - Write the completed formulae with those same numbers at the bottom.
  • Step 5 - If the numbers on each part are the same (e.g. Na1 Cl1 or Mg2 O2), ignore them and rewrite the formulae without them (e.g. Na Cl or Mg O).
  • Step 6 - Brackets may be used around radicals (groups of atoms that are charged e.g CO3).

Elements


EXAMPLES OF CHEMICAL NAMES OF COMPOUNDS

CHEMICAL FORMULA

CHEMICAL NAME

CO2carbon dioxide
COcarbon monoxide
Na Clsodium chloride
Cu Ocopper oxide
Ag Brsilver bromide
K Ipotassium iodide
H Clhydrogen chloride (hydrochloric acid)
NH4 Clammonium chloride
K OHpotassium hydroxide
Na OHsodium hydroxide
Ca (OH)2calcium hydroxide
Ca Scalcium sulphide
Na NO3sodium nitrate
H NO3hydrogen nitrate (nitric acid)
Na HCO3sodium bicarbonate
Zn SO4zinc sulphate
Mg CO3magnesium carbonate
Ca SO4calcium sulphate
Cu CO3copper carbonate
Al PO4aluminium phosphate
Fe SO4iron sulphate
Fe CO3iron carbonate
NH4 NO3ammonium nitrate
NH4 HCO3ammonium bicarbonate
H2 SO4hydrogen sulphate (sulphuric acid)
Na2 SO4sodium sulphate
(NH4)2 CO3ammonium carbonate

EXAMPLES OF NUMBERS AND TYPES OF ATOMS
IN VARIOUS ELEMENTS AND COMPOUNDS

NAME OF
SUBSTANCE

CHEMICAL
FORMULA

ELEMENT OR COMPOUND

NUMBER AND TYPE
OF ATOMS IN MOLECULE

HydrogenH2element2 hydrogen atoms
Carbon dioxideCO2compound1 carbon atom
2 oxygen atoms
WaterH2Ocompound2 hydrogen atoms
1 oxygen atom
MethaneCH4compound1 carbon atom
4 hydrogen atoms
Sodium hydroxideNaOHcompound1 sodium atom
1oxygen atom
1 hydrogen atom
Calcium hydroxideCa(OH)2compound1 calcium atom
2 oxygen atoms
2 hydrogen atoms

 
Subpages (1): Online test for valency
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