Which electrons are involved in chemical bonding

Again, polar covalent bonds tend to occur between non-metals. Finally, for atoms with the largest electronegativity differences such as metals bonding with nonmetals , the bonding interaction is called ionic, and the valence electrons are typically represented as being transferred from the metal atom to the nonmetal.

Once the electrons have been transferred to the non-metal, both the metal and the non-metal are considered to be ions. The two oppositely charged ions attract each other to form an ionic compound. Covalent interactions are directional and depend on orbital overlap, while ionic interactions have no particular directionality. Each of these interactions allows the atoms involved to gain eight electrons in their valence shell, satisfying the octet rule and making the atoms more stable.

These atomic properties help describe the macroscopic properties of compounds. For example, smaller covalent compounds that are held together by weaker bonds are frequently soft and malleable. On the other hand, longer-range covalent interactions can be quite strong, making their compounds very durable. Ionic compounds, though composed of strong bonding interactions, tend to form brittle crystalline lattices.

Ionic bonds are a subset of chemical bonds that result from the transfer of valence electrons, typically between a metal and a nonmetal. Ionic bonds are a class of chemical bonds that result from the exchange of one or more valence electrons from one atom, typically a metal, to another, typically a nonmetal. This electron exchange results in an electrostatic attraction between the two atoms called an ionic bond.

An atom that loses one or more valence electrons to become a positively charged ion is known as a cation, while an atom that gains electrons and becomes negatively charged is known as an anion.

This exchange of valence electrons allows ions to achieve electron configurations that mimic those of the noble gases, satisfying the octet rule. The octet rule states that an atom is most stable when there are eight electrons in its valence shell.

Atoms with less than eight electrons tend to satisfy the duet rule, having two electrons in their valence shell. By satisfying the duet rule or the octet rule, ions are more stable. An anion is indicated by a negative superscript charge - something to the right of the atom.

Similarly, if a chlorine atom gains an extra electron, it becomes the chloride ion, Cl —. Both ions form because the ion is more stable than the atom due to the octet rule. Once the oppositely charged ions form, they are attracted by their positive and negative charges and form an ionic compound. Ionic bonds are also formed when there is a large electronegativity difference between two atoms. This difference causes an unequal sharing of electrons such that one atom completely loses one or more electrons and the other atom gains one or more electrons, such as in the creation of an ionic bond between a metal atom sodium and a nonmetal fluorine.

Formation of sodium fluoride : The transfer of electrons and subsequent attraction of oppositely charged ions. To determine the chemical formulas of ionic compounds, the following two conditions must be satisfied:. This is because Mg has two valence electrons and it would like to get rid of those two ions to obey the octet rule.

Fluorine has seven valence electrons and usually forms the F — ion because it gains one electron to satisfy the octet rule. Therefore, the formula of the compound is MgF 2. The subscript two indicates that there are two fluorines that are ionically bonded to magnesium. On the macroscopic scale, ionic compounds form crystalline lattice structures that are characterized by high melting and boiling points and good electrical conductivity when melted or solubilized.

In forming the same ionic compound, Cl gains an electron to become the Cl - anion, which also has a stable octet of outer-shell electrons. In the remainder of this chapter, the octet rule will be used in explaining the formation of chemical compounds consisting of two or more different elements bonded together. It was already used to show the bonding in ionic sodium chloride in Figure 3.

One of the best compounds for showing the octet rule in covalent compounds is methane, CH 4 , shown in Figure 4. The molecule of CH 4 is produced when an atom of carbon with 4 outer electrons see Figure 3. Each H atom has 1 electron to donate to the sharing arrangement, so by each of 4 H atoms contributing an electron the carbon atom can gain an octet. Each of the H atoms has access to 2 electrons in the single covalent bond that connects it to the C atom.

Carbon is a major component of nearly all biological molecules. Elements are characterized by their atomic structure. While the subatomic structure of the atom is a major topic of interest in chemistry, physics and biophysics, we will only discuss the basic structure that will provide sufficient information for the construction of molecules in the context of this course. Atoms have a central nucleus with positively charged protons and neutral neutrons; negatively charged electrons circle the nucleus.

The electrons that are involved in chemical bonding are those electrons in the outermost orbit, referred to as valence electrons. On the periodic table below, you can view each of the atoms while hiding all but the outermost electrons. Atomic mass, the sum of the number of protons and neutrons in the atomic structure, is a particularly useful measure of each element.

By summing the atomic mass of all the atoms in a molecule, one can estimate the molecular mass of the molecule, which is then expressed in atomic mass units, or Daltons. This table shows the masses of the six atoms of the elements listed above, which can also be found in the upper right-hand corner of the box for each element in the periodic table.

To calculate the mass of a molecule, we find the mass of each individual atom in the molecule and add them together. For example, a water molecule H 2 O contains one oxygen atom that has a mass of 16 amu atomic mass units and two hydrogen atoms that each have a mass of one amu.

The electronegativity of an element is the degree to which an atom will attract electrons in a chemical bond. Chemical bonds result when atoms of the same element e.

There are two major types of chemical bonds: ionic and covalent. Covalent bonds can further be divided into polar covalent and nonpolar covalent bonds. A polar covalent bond is a type of covalent bond that results in unique interaction between molecules. A molecule is a group of at least two atoms in a specified arrangement held together by covalent chemical bonds.

These polar bonds will interact with other polar bonds through an intermolecular attraction known as hydrogen bonding, such as that found between water molecules. Both the strong ionic and covalent chemical bonds and the weaker intermolecular forces are important in the functioning of the cell.

Recall, that an ion is an atom with a gain or loss of electrons, always valence electrons. The number of protons is not equal to the number of electrons.