Ionic Bonding © Copyright NewPath Learning. All Rights Reserved. 94-4839 Visit www.newpathlearning.com for Online Learning Resources. Charged Particles A normal atom has a neutral charge with an equal number of protons and electrons. For example, a neutral atom of sodium has eleven protons and eleven electrons. However, since atoms are more stable with a full valence shell, an atom can gain or lose electrons to become stable. If a sodium atom loses 1 electron, it will have a full valence shell but it will no longer be neutral. The atom will now have 11 protons and 10 electrons for a net charge of +1. A neutral atom becomes charged when there are an unequal number of protons and electrons. For example, calcium loses two valence electrons, to form a positive ion with a +2 net charge which is expressed as Ca2+. Alternatively, an oxygen atom gains two electrons to form a negative ion with a -2 charge, which is expressed as O2-. Calcium Oxygen 8 protons 10 electrons -2 net charge – O2- 20 protons 18 electrons +2 net charge – Ca2+ Ionic Bonds Ionic bonds form as a result of the attraction between positive and negative ions. Ionic bonding normally occurs between metal atoms and nonmetal atoms. Atoms with partially filled outer shells are unstable. To become stable, the metal atom loses one or more electrons in its outer shell, forming a positively charged ion or cation with a stable electron configuration. These electrons are then gained by the nonmetal atom, causing it to form a negatively charged ion or anion, also with a stable electron configuration. The attraction between the oppositely charged ions causes them to come together and form an ionic bond. In this example, sodium (Na) and chlorine (Cl) ions are attracted to each other in a 1:1 ratio and combine to form sodium chloride (NaCl), common table salt. creates a full valence shell Sodium ion (+) metal Chlorine ion (-) non-metal (cation) (anion) Cl Na + – forms an ionic bond table salt Cl- Na+ Forming Ions A neutral atom that becomes charged by gaining or losing electrons is called an ion. An atom can acquire a positive or negative charge depending on whether the number of electrons is greater or less than the number of protons in the atom. An atom with more electrons than protons, has a negative charge and is a negative ion, or anion. However, an atom with more protons than electrons, has a net positive charge and is a positive ion, or a cation. Since an electron and a proton have equal but opposite unit charges, the charge of an ion is always expressed as a whole number of unit charges and is either positive or negative. Sodium atom (neutral) single valence electron 11 protons 11 electrons 11+ (-11) = 0 0 neutral charge full valence shell Sodium ion (+1) 11 protons 10 electrons 11+ (-10) = +1 +1 net charge
Ionic Bonding © Copyright NewPath Learning. All Rights Reserved. 94-4839 Visit www.newpathlearning.com for Online Learning Resources. Pause and Review Describe and illustrate ionic bonding. _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________ Describe and illustrate the formation of ions. _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________ Describe and illustrate a charged particle. _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________
