notes of atoms and molicules
Answers
Atomic mass:
Atomic mass is the mass of an atom.
The relative atomic mass of an atom of an element is the number of times an atom of that element is heavier than 1/12th of the mass of a carbon-12 atom.
Molecule: A molecule is the smallest particle of an element or compound that can exist independently.
Examples:
H2O, O2, O3 etc.
Single Hydrogen is not a molecule. When this hydrogen bonds to other hydrogen (H2) or to other elements like oxygen (H2O), a molecule is formed.
Atomicity: The number of atoms constituting a molecule is referred to as atomicity.
A molecule which contains only one atom is called monatomic
Example: Noble gases like Helium (He), Neon (Ne), Argon (Ar) etc.
A molecule which contains two atoms is called diatomic
Example: Hydrogen (H2), Chlorine (Cl2), Nitrogen (N2) etc.
A molecule which contains three atoms is called triatomic.
Example: O3, H2O.
A molecule which contains four atoms is called teraatomic.
Example: Phosphorus (P4).
A molecule which contains more atoms is called polyatomic.
Example: Sulphur (S8).
Compound: Elements combine to form compounds. Thus a molecule of a compound has two or more elements.
Example: Water (H2O), Glucose (C6H12O6), Calcium oxide (CaO), Sodium chloride (NaCl) etc.
Laws of Chemical Combination:
The Law of conservation of mass: This law states that, the total mass of reactants is equal to the total mass of products. In any chemical reaction, the total mass of the substance before and after the reaction is the same although its matter undergoes a physical change.
Law of Definite Proportions: According to law of definite proportions, in a chemical substance, the elements are always present in definite proportions by mass.
Law of Multiple Proportions: When two elements combine to form different compounds, then the weight of one is constant and the other has a simple ratio.
Atom: After a series of experiments Dalton concluded that all matter must be composed of tiny particles, which cannot be further divided. He called them atoms.
Definition of an atom: The smallest particle of an element is called an atom.
Dalton’s Postulates:
Answer:When a cation gets close to an anion, they link up because of their different net charges — positive charges attract negative charges and vice versa. When two or more atoms link up, they create a molecule . A molecule of water is made of two atoms of hydrogen (H) and one atom of oxygen (O). The molecular mass is the sum of the masses of all the atoms in the molecule. A collection of molecules is called a compound
Explanation: