Atoms And Molecules
What is an ion?
An ion is a charged particle. It can be either positively charged or negatively charged. A negatively charged ion is called an anion and a positively charged ion is called a cation. Ions may consist a single charged atom or a group of atoms that have a net-charge on them. Such a group of atoms carrying a net charge is known as a polyatomic ion. For example, Na+ is a single charged atom and is known as sodium cation. Cl– is a single charged atom and is known as chloride anion. NO-3 is a group of atoms carrying net negative charge and is known polyatomic anion.
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When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen ? Which law of chemical combination will govern your answer?
What are polyatomic ions? Give examples.
(a) Magnesium chloride
(b) Calcium oxide
(c) Copper nitrate
(d) Aluminium chloride
(e) Calcium carbonate
Give the names of the elements in the following compounds.
(a) Quick lime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate.
Calculate the molar mass of the following substances:
(a) Ethylene
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3.
What is the mass of:
(a) 1 mole of nitrogen atoms
(b) 4 moles of aluminium atoms
(c) 10 moles of sodium sulphite.
Convert into mole
(a) 12 gm of oxygen gas
(b) 20 gm of water
(c) 22 gm of carbon dioxide.
What is the mass of?
(a) 0.2 mole oxygen atoms.
(b) 0.5 mole of water molecules.
Calculate the number of molecules of sulphur (S8) present in 16 gm of solid sulphur.
Calculate the number of aluminium ions present in 0.56 gm of aluminium oxide.
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