This particular resource used the following sources:. Skip to main content. Atoms, Molecules, and Ions. Search for:. Ionic Bonds. Learning Objective Summarize the characteristic features of ionic bonds. Key Points Ionic bonds are formed through the exchange of valence electrons between atoms, typically a metal and a nonmetal. The loss or gain of valence electrons allows ions to obey the octet rule and become more stable.
Why do elements share electrons? Can carbon form 4 bonds? How many atoms can hydrogen bond with? What causes dipole interactions? How does chemical bonding relate to life?
How does chemical bonding affect solubility? Ionic bonds differ from covalent bonds. Both types result in the stable electronic states associated with the noble gases.
However, in covalent bonds, the electrons are shared between the two atoms. All ionic bonds have some covalent character, but the larger the difference in electronegativity between the two atoms, the greater the ionic character of the interaction.
Ionic Bonding — YouTube : In this video, Paul Andersen explains how ionic solids form when cations and anions are attracted. Lattice energy is an estimate of the bond strength in ionic compounds. It is defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. Alternatively, lattice energy can be thought of as the energy required to separate a mole of an ionic solid into the gaseous form of its ions that is, the reverse of the reaction shown above.
Lattice energy cannot be determined experimentally due to the difficulty in isolating gaseous ions. The energy value can be estimated using the Born-Haber cycle, or it can be calculated theoretically with an electrostatic examination of the crystal structure.
This model emphasizes two main factors that contribute to the lattice energy of an ionic solid: the charge on the ions, and the radius, or size, of the ions. The effect of those factors is:. Lattice energies are also important in predicting the solubility of ionic solids in H 2 O. Ionic compounds with smaller lattice energies tend to be more soluble in H 2 O. Lattice Energies — Chemistry Tutorial : This tutorial covers lattice energy and how to compare the relative lattice energies of different ionic compounds.
Ionic formulas must satisfy the noble gas configurations for the constituent ions and the product compound must be electrically neutral. An ionic bond is formed through the transfer of one or more valence electrons, typically from a metal to a non-metal, which produces a cation and an anion that are bound together by an attractive electrostatic force. On a macroscopic scale, ionic compounds, such as sodium chloride NaCl , form a crystalline lattice and are solids at normal temperatures and pressures.
The charge on the cations and anions is determined by the number of electrons required to achieve stable noble gas electronic configurations. The ionic composition is then defined by the requirement that the resulting compound be electrically neutral overall. For example, to combine magnesium Mg and bromine Br to get an ionic compound, we first note the electronic configurations of these atoms valence level in indicated in italics :.
In order to achieve noble gas configurations, the magnesium atom needs to lose its two valence electrons, while the bromine atom, which has 7 valence electrons, requires one additional electron to fill its outer shell. Therefore, for the resulting compound to be neutral, two bromine anions must combine with one magnesium cation to form magnesium bromide MgBr 2. Ionic bonds require at least one electron donor and one electron acceptor. In contrast, atoms with the same electronegativity share electrons in covalent bonds, because neither atom preferentially attracts or repels the shared electrons.
Ionic bonding is the complete transfer of valence electron s between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.
Ionic bonds require an electron donor, often a metal, and an electron acceptor, a nonmetal. Ionic bonding is observed because metals have few electrons in their outer-most orbitals. By losing those electrons, these metals can achieve noble gas configuration and satisfy the octet rule.
Similarly, nonmetals that have close to 8 electrons in their valence shells tend to readily accept electrons to achieve noble gas configuration. In ionic bonding, more than 1 electron can be donated or received to satisfy the octet rule.
The charges on the anion and cation correspond to the number of electrons donated or received. In ionic bonds, the net charge of the compound must be zero. This sodium molecule donates the lone electron in its valence orbital in order to achieve octet configuration. This creates a positively charged cation due to the loss of electron. This chlorine atom receives one electron to achieve its octet configuration, which creates a negatively charged anion.
The predicted overall energy of the ionic bonding process, which includes the ionization energy of the metal and electron affinity of the nonmetal, is usually positive, indicating that the reaction is endothermic and unfavorable. However, this reaction is highly favorable because of the electrostatic attraction between the particles.
0コメント