If a two-electron covalent bond breaks symmetrically, each of the two atoms receive one electron; it is a homolytic bond cleavage.
A homolytic cleavage is shown using a fish-hook arrow, which implies one-electron movement.
Around the early 1800s, scientists began to notice the presence of isomerism in all types of compounds; however, at the time, it was referred to using different names.
The term allotrope was used to describe different varieties of an element that existed in different physical forms, such as diamond or graphite for carbon or monoclinic or rhombic for sulfur. Polymorphism was used to explain compounds that occurred in more than one crystalline form, like aragonite and calcite, both crystalline forms of calcium carbonate.
Learning Objective: To study how molecular weight, molecular shape, functional group, and carbon number impact density.
Skill Level - Intermediate
Prerequisites:
Common names of alkanes
IUPAC, an international body engaged in developing standards for naming chemical elements and compounds, has laid several rules known as 'IUPAC rules' to identify a molecule by its parent alkane chain and the functional group. It has assigned various suffixes to identify organic chemistry's commonly seen functional groups.
Learning Objective: To calculate the number of active hydrogen bonds per molecule and techniques for detecting hydrogen bonds.
Skill Level – Intermediate
Prerequisites:
Alpha hydrogens
Hydrogen bonding is an attractive intermolecular interaction stronger than Vander Waals forces that exclusively occurs when the Hydrogen atom is sandwiched between two highly electronegative atoms N, O, or F, one to which it is covalently bonded and the other it attracts electrostatically.
The Atomic number (symbol Z) uniquely identifies an element and is equal to the number of protons present in the nucleus of an atom.
For example, atomic number 6 identifies the Carbon atom with 6 protons in its nucleus. An uncharged Carbon atom will also have 6 electrons in the outer nuclear region, equal to its atomic number.
The very premise of a covalent bond is electron sharing. As two atoms share one electron each to form one covalent bond, they may likely share more than once and form more bonds. This information on the number of connections between two atoms is revealed from the Bond Order.
So, the Bond Order measures the number of bonds between the two atoms in a molecule. The number can be integers like 1, 2, or 3 for single, double, or triple bonds or non-integers like 0.5, 1.3, 1.5, etc.
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Before the Exam
If a crystalline solid is cut with a sharp object, it would always give parts with smooth edges whereas an amorphous solid would cut into surfaces with rough, uneven edges. Crystalline solids are therefore said to have cleavage property, and amorphous solids do not show cleavage property.