Step into the Generalities in Chemistry, where the foundations of this diverse field are explored. Delve into the fundamental principles and concepts that underpin the study of matter and its transformations. From atomic structure and chemical bonding to states of matter and chemical reactions, uncover the key elements that shape our understanding of chemistry. Embark on a journey of discovery as you unravel the secrets and intricacies of this fascinating science.
Atoms combine with each other to form compounds with different properties from the atoms they contain. The force of attraction between atoms in a compound is a chemical bond. One type of chemical bond is the ionic bond. This corresponds to a force of attraction between species (ions) with opposite charges. Ions with a positive … Read more
Atoms often gain, lose or share electrons trying to reach the same number of electrons as the noble gases closest to them on the periodic table. Noble gases have very stable electron arrangements, as revealed by their high ionization energies, their low affinity for additional electrons, and their general lack of chemical reactivity. Since all … Read more
Chemists use chemical formulas to express the composition of molecules and ionic compounds by means of chemical symbols. Composition means not only the elements present, but also the ratio in which the atoms combine. It is necessary to become familiar with two types of formulas: molecular formulas and empirical formulas. Molecular formulas A molecular formula … Read more
Since the beginnings of experimental chemistry, scientists have recognized acids or bases by their characteristic properties. Acids taste sour (e.g., citric acid in lemon juice) and cause certain dyes to change color (e.g., litmus paper turns red when in contact with acidic substances). The word acid comes from the Latin word acidus, which means sour … Read more
What is the Nernst’s distribution law? The Nernst’s distribution law (or Nernst’s partitioning law) was enunciated by the, Nobel prize in 1920, German physical chemist Walther Hermann Nernst (1864–1941), and explains how a solute will be distributed between two immiscible solvents. It is a concept widely used in solutions of immiscible liquids. If we have two non-miscible solvents and we … Read more
What is Proust’s law? Proust’s law or law of definite proportions can be stated as follows: When two elements combine to give rise to another compound, they always do so in a constant mass ratio. In 1799, the French chemist Joseph Louis Proust (1754-1826) found in different samples of a compound the same elements in … Read more
What is Lavoisier’s law? Lavoisier’s law or the law of conservation of mass explains that during a chemical reaction there is no change of mass, i.e. the sum of the mass of the reactants (before the reaction takes place) is equal to the mass of the products (after the reaction takes place). It can be … Read more
Dalton’s law Dalton’s law or the law of multiple proportions can be stated as follows: When two elements combine to form more than one compound, a constant mass of one of them combines with variable masses of the other. These variable masses have a simple integer relationship to each other. In 1803, the English chemist … Read more
A molecule is an aggregate of at least two atoms in a definite placement that are held together by chemical forces (also called chemical bonds). A molecule can contain atoms of the same element or atoms of two or more elements, always in a fixed ratio. Thus, a molecule is not always a compound, which, … Read more
What is a mole? In chemistry, quantities of substances are traditionally measured in volume or mass. Thus, the concept of mole (symbol mol) is very important, since it allows stoichiometric calculations in chemical reactions. In this way, we can indicate what ratio exists between reactants and products. For example, in the reaction of nitric acid formation, one mole … Read more
