- To determine the definition of atoms and molecules and the difference of those notions.
- Understanding isotopes, atomic mass, and molecular mass.
- Understanding mole concept and molar mass.
According to Dalton’s atomic theory, atoms are the basic units of matter and the defining structure of elements. Atoms are made up of three parts: protons (positively charged), neutrons (uncharged) and electrons (negatively charged).
For example: Sodium ( ) has 11 protons, 12 neutrons and 11 electrons.
Molecules form when two or more atoms form chemical bonds with each other. It doesn’t matter if the atoms are the same or are different from each other.
3. Isotopes: …show more content…
For example: There are 5 isotopes of nickel in the nature, including: , , , , .
4. Atomic mass:
Atomic mass is the mass of an isotope of an element measured in units base on 1/12 the mass of the cacbon -12 atom. The atomic mass is equal to total mass of protons and neutrons ( Because the mass of electrons is insignificant )
For example: There are 5 isotopes of nickel in the nature, including: (67.78%), (26.16%), (1.25%), (3.66%), (1.15%).
Thus, average atomic mass of nickel will be 58.8127 u
5. Molecular mass:
Molecular mass is a number equal to the sum of atomic masses of the atoms in a molecule.
For example: The molecular mass of = 12 + 1 x 4 = 16.0 u
6. Mole concept:
Mole is defined as the amount of a substance, which contains the same number of chemical units as there are atoms in exactly 12 grams of pure cacbon. A mole represents the quantity of material, which contains one Avogadro’s number ( ) of chemical units of any substance.
For example: one mol of sodium ions ( ) = ions
7. Molar mass:
Molar mass is the mass of one mole of a substance .
For example: How many grams are there in 5 mol of benzene ( )
Molar mass of benzene ( ) = 78.0 …show more content…
- To Study about types of chemical reactions such as combination, decomposition, displacement and double displacement.
- Find out about oxidation and reduction (redox reactions).
1. Combination reactions:
Combination reactions are reactions in which two reactants combine to form one product.
For example: when a metal undergos a combination reaction with oxygen, a metal oxide is formed. 2. Decomposition reactions:
Decomposition reactions are those in which one compound breaks down to form two or more products.
For example: Applying heat and electric in aluminothermic reaction: 3. Displacement reactions:
Displacement reactions are those in which an element reacts with a compound to form a new compound and release a different element.
For example: Highly pure silicon for computer chips is produced through a displacement reaction. In this reaction, hydrogen reacts with silicon tetrachloride to form hydrogen chloride and release silicon. 4. Double displacement reactions:
Double displacement reactions are those in which two compounds exchange ions to form two new compounds.
For example: In the reaction of copper sulphate and hydrogen sulphide, copper sulphide and sulphuric acid are