University:
Kentucky State University
Course:
CHE 101 | General Chemistry I
Academic year:

2022
Views:

237

Pages:

5
Author:

Shyanne Johnson

Compounds Molecules and compounds • Compounds are formed by atoms bonding together by either: - Covalent bonds-> Molecular compounds - Ionic bonds -> Ionic compounds or salts • The molecule is the smallest unit of the compound holding its characteristic chemical properties. • “A compound is made of different elements in definite proportions”. Types of compounds Ionic compounds - Products of reaction between acids and bases - The formed compound is known as salt. which is formed of cations and anions - Ionic compounds are formed as crystal structure with the cations and anions according to their ratios in the molecule. - They have high melting and boiling point, low or no vapor pressure, good electric conductivity of their solution in water. Types of compounds Molecular compounds  Includes diatomic elements (H, N, O and Halogens) and non-metallic covalently bonded compounds e.g. H2O, NH3, CH4, C2H5OH  They have lower melting and boiling point.  They exist in gas, liquid and solid phase states.  They are easy to volatilize. Molecule representation Molecules are represented by the following methods: • Molecular formula: Each element followed by its number of atoms in the molecule (written in subscript) e.g. H2O, CO2, C4H8 • Empirical formula: the simplest ratio of atoms in a compound. For example in butene C4H8, the empirical formula is CH2 • Structural formula: Atoms connected by lines corresponding to bonds