Química orgânica

Bonding in Organic Compounds

Chapter 1

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Bonding in Organic Compounds

CHAPTER SUMMARY
Organic chemistry is the study of compounds of carbon. This is a separate branch of chemistry because of the large numbers of organic compounds and their occurrences and applications.

1.1 Elements and Compounds – Atoms and Molecules Elements are the fundamental building units of substances. They are composed of tiny particles called atoms; atoms are the smallest particles of an element that retains the properties of that element. Atoms are composed of a positively charged nucleus that consists of protons (charge = +1, mass = 1) and neutrons (charge = 0, mass = 1). The nucleus is surrounded by negatively charged electrons that have negligible mass. Elements combine to form compounds. A molecule is the smallest particle of a compound that retains the properties of the compound; atoms bond to one another to form a molecule.

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Chapter 1 1.2 Electron Configuration

Bonding in Organic Compounds

A. Atomic Number and Atomic Mass The atomic number of an atom is the number of protons in the nucleus; this is equal to the number of electrons surrounding the nucleus in a neutral atom. The mass number is the number of protons plus neutrons in the nucleus. Isotopes are atoms with the same number of electrons and protons but different numbers of neutrons; they have the same atomic number but different mass numbers. The atomic mass of an element is the weighted average of the naturally occurring isotopes. B. Atomic Orbitals The space electrons occupy around an atomic nucleus is described by atomic orbitals. The most common orbitals in organic chemistry are sorbitals, spherical orbitals with the atomic nucleus located in the center, and dumbbell shaped p-orbitals in which the nucleus is between the lobes. C. Filling Atomic Orbitals Orbitals exist in energy levels or shells (numbered 1-7). An atomic orbital can be occupied by 0, 1, or 2 electrons. Atomic orbitals are filled