Chemical Bonding Basics
By John T. Moore
Part of the Chemistry For Dummies Cheat Sheet
In bonding, atoms lose, gain, or share electrons in order to have the same number of electrons as the noble gas that's nearest on the periodic table. Ionic, covalent, and metallic bonds are formed by combinations of metals and nonmetals.
· Metal + nonmetal = ionic bond
· Nonmetal + nonmetal = covalent bond
· Metal + metal = metallic bond
When two elements engage in ionic bonding, one or more electrons are transferred from the metal to the nonmetal, forming ions (charged atoms). The metal, having lost one or more electrons, forms a cation, an ion with a positive charge; the nonmetal, having gained one or more electrons, becomes an anion, an ion with a negative charge.
When two elements form a covalent bond, one or more electron pairs are shared between these two elements. In metallic bonding, which occurs in metals (either a pure metal or an alloy of two or more metals), the valence (outer shell) electrons are donated to a "sea of electrons."
Chemistry Glossary
Archimedes Principle
A principle discovered by the Greek mathematician Archimedes which states that the volume of a solid is equal to the volume of water it displaces.
Chemistry Glossary
atomic number
The number of protons in the nucleus of an atom.
Chemistry Glossary
Bohr model
A model of atomic structure developed by Niels Bohr, a Danish scientist. In this model, electrons occur in orbits of differing energy levels around the nucleus of an atom.
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condensation
The change in the physical state of matter from a gaseous state to a liquid state.
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deposition
The change in the physical state of matter from a gaseous state to a solid state without ever becoming a liquid. The reverse of sublimation.
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electrolytes
Substances that can conduct electricity either in the molten state or when dissolved in water.
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electron configuration notation
A method used by chemists to represent electrons in bonding and chemical reactions.
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electronegativity
A measure of an atom’s strength to attract a bonding pair of electrons to itself.
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energy level diagram
A method used by chemists to diagram the electrons for an atom (including orbitals and subshells) in bonding and chemical reactions.
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heterogeneous mixture
A mixture whose composition varies from position to position within a sample.
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homogeneous mixture
A mixture whose composition is the same from position to position within a sample.
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isotopes
Atoms of the same element that have varying numbers of neutrons.
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mass number
The sum of the protons and neutrons in a particular isotope; also called atomic weight.
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nonelectrolytes
Substances that do not conduct electricity in the molten state or when dissolved in water.
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nuclear fission
A nuclear reaction in which an atom’s nucleus splits into smaller parts.
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nuclear fusion
A process in which lighter nuclei of atoms join together into a heavier nucleus; essentially the opposite of nuclear fission.
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nuclear reaction
Any reaction that involves a change in nuclear structure.
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periodic table
A table that displays all known chemical elements in an arrangement that is based on the properties of the elements; changes over time as new elements are discovered.
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quantum mechanical model
A model of atomic structure that is based on mathematics and can be used to explain observations made on complex atoms.
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radioactivity
The spontaneous decay of an unstable nucleus in an atom.
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SI system
A worldwide measurement system that is based on the older metric system. The SI comes from the French Systeme International.
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sublimation
The change in the physical state of matter from a solid state to a gaseous state without ever becoming a liquid (such as dry ice).
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valence electrons
The electrons in the outermost energy level of an atom, the farthest away from the nucleus.