File Name: structure of atoms molecules and chemical bonds .zip
The concepts of atoms and bonds in molecules which appeared in chemistry during the nineteenth century are unavoidable to explain the structure and the reactivity of the matter at a chemical level of understanding. Although they can be criticized from a strict reductionist point of view, because neither atoms nor bonds are observable in the sense of quantum mechanics, the topological and statistical interpretative approaches of quantum chemistry quantum theory of atoms in molecules, electron localization function and maximum probability domain provide consistent definitions which accommodate chemistry and quantum mechanics.
Share Supplemental Resources Start a Discussion. It is a substance made up of matter that holds atoms together. It is not made up of matter.
To understand bond formation, it is necessary to know the general features of the electronic structure of atoms—that is, the arrangement of electrons around the central nucleus. For background information about this subject and further details, see atom. The number of protons in the nucleus is the atomic number , Z , of the element. A proton is positively charged, and an electron carries an equal but opposite negative charge. For an atom to be electrically neutral, it must contain the same number of extranuclear electrons as there are protons in the nucleus. Hence, the number of electrons in a neutral atom of atomic number Z is also Z. A hydrogen atom consequently has one electron, and a carbon atom has six electrons.
The atoms of each element differ by their number of protons, neutrons, and electrons. For example, hydrogen has one proton, one electron, and no neutrons, while carbon has six protons, six neutrons, and six electrons. The number and arrangement of electrons of an atom determine the kinds of chemical bonds that it forms and how it reacts with other atoms to form molecules. There are three kinds of chemical bonds:. The atom that gains electrons has an overall negative charge, and the atom that donates electrons has an overall positive charge. The attraction of the positive ion to the negative ion constitutes the ionic bond. A plus or minus sign following a chemical symbol indicates an ion with a positive or negative charge, which results from the loss or gain of one or more electrons, respectively.
Chemical bonding describes a variety of interactions that hold atoms together in chemical compounds. Chemical bonds are the connections between atoms in a molecule. These bonds include both strong intramolecular interactions, such as covalent and ionic bonds. They are related to weaker intermolecular forces, such as dipole-dipole interactions, the London dispersion forces, and hydrogen bonding. The weaker forces will be discussed in a later concept.
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. In quantum physics , organic chemistry , and biochemistry , the distinction from ions is dropped and molecule is often used when referring to polyatomic ions. In the kinetic theory of gases , the term molecule is often used for any gaseous particle regardless of its composition. This violates the definition that a molecule contain two or more atoms, since the noble gases are individual atoms. A molecule may be homonuclear , that is, it consists of atoms of one chemical element , as with two atoms in the oxygen molecule O 2 ; or it may be heteronuclear , a chemical compound composed of more than one element, as with water two hydrogen atoms and one oxygen atom; H 2 O.
Use the concept of potential energy to describe how a covalent bond forms. Bond energy is directly proportional to bond order. Atoms form double or triple covalent bonds if they can attain a noble gas structure by doing so.
Draw the line bond structures of following types of hydrocarbons using four carbon atoms: a. Give the molecular formula, the line bond structural formula, the condensed structural formula, and the skeletal structure for pentane.
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Жертва ощутила прикосновение смерти, и началась совершенно иная игра. Беккер мчался, не видя ничего вокруг, постоянно сворачивал, избегая прямых участков. Шаги неумолимо приближались.