Although the outermost electrons can be easily determined, the apparent valence electrons considered in chemical reactivity are complex and fluctuated. Electrons going into d sublevel can play either a role of valence electrons or shielding electrons. So there is not always a certain number of apparent valence electrons. The number of apparent valence electrons for the first transition metal period is shown in the table below. The chemical reactivity of an atom is mainly determined by valence electrons.
Atoms which have a complete shell of valence electrons tend to be chemically inert. Atoms with one or two valence electrons are highly reactive. This phenomenon can be explained by Hund's rule, which states that orbitals that are empty, half-full, or full are more stable than those that are not. For example, Ne is chemically inert because it has two valence electrons that fill its outermost shell which makes it stable compared to atoms such as Al, which has three valence electrons, but its valence electrons does not fill its outermost shell.
Although core electrons do not take part in chemical bonding, they play a role in determining the chemical reactivity of an atom. This influence is generally due to the effect it has on valence electrons. Each of these orbitals serves to create a shell of electrons in the atom. Valence electrons are the electrons orbiting the nucleus in the outermost atomic shell of an atom.
Electrons that are closer to the nucleus are in filled orbitals and are called core electrons. Valence electrons are the farthest from the positive charge the protons and thus tend to be easier to remove than core electrons; this means that it takes them less energy to move far away from the atom. This difference comes from the electric force being an inverse square law. Removing an electron any of them from a neutral atom turns the atom into an ion. Moreover, there are two types of electrons as valence electrons and core electrons.
Overview and Key Difference 2. What are Valence Electrons 3. What are Core Electrons 4. Valence electrons are the electrons in an atom that participate in the chemical bond formation. When chemicals bonds form, an atom can either gain electrons, donate electrons, or share electrons. The ability to donate, gain, or share these electrons depends on the number of valence electrons they have. For example, when an H 2 molecule is formed, one hydrogen atom gives one electron to the covalent bond.
Thus, two atoms share two electrons. Therefore, a hydrogen atom has one valence electron. In the formation of sodium chloride, one sodium atom gives out one electron, whereas a chlorine atom takes an electron.
It happens in order to fill an octet in their valence orbitals. There, sodium has only one valence electron, and chlorine has seven. Therefore, by looking at the valence electrons, we can determine the chemical reactivity of the atoms. The number of valence electrons is equivalent to their group number.
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