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Formation of Ions. Formation of Ions. Elements tend to lose or gain electrons to fill their outermost energy levels with eight electrons depending on their electron affinity As a general rule, metals will give electrons away and nonmetals will accept electrons.
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Formation of Ions • Elements tend to lose or gain electrons to fill their outermost energy levels with eight electrons depending on their electron affinity • As a general rule, metals will give electrons away and nonmetals will accept electrons.
fill their outermost energy levels with eight electrons: • Attain Noble Gas Status • Sodium: 1s2 2s2 2p6 3s1 • [Ne] 3s1 • Chlorine: 1s2 2s2 2p6 3s2 3P5 • [Ne] 3s2 3P5
Formation of Ions • This causes an imbalance of charge (more or less electrons than protons) • This imbalance in the element is called “ionizing”, and the element is transformed into an “ion”
Formation of Ions • The charge of an ion can be computed by subtracting the number of protons by the new number of electrons: • Chlorine would gain 1 electrons so: 17 - 18 = -1 charge
Formation of Ions • Sodium would lose 1 electrons so: 11 - 10 = +1 • An ion and its charge is represented by the element's symbol and then the charge is written after it as a superscript: Cl-1 Na+1
Formation of Ions • The general term for a positive ion is a cation. • The general term for a negative ion is an anion.
Formation of Ions • It may be easier to draw the electron dot for the specific element and then see if the element will add or subtract electrons to form eight electrons in its outermost shell.
Formation of Ions • (four or more dots, add electrons; four or less dots, subtract electrons.) Subtract one electron +1 Li Li
Formation of Ions • Remembering the Periodic Law will help you realize that all of the elements in each column will have the same charge as an ion:
Formation of Ions • Na = Na+1 • K = K+1 • Li = Li+1 • and so on
Formation of Ions • Unfortunately, since the transition metals have only two electrons in their outermost energy level, we cannot use the Rule of Eight to determine their ionic charge.
Formation of Ions • To accommodate this, we will assume that an ion of a transition metal will be +2 unless otherwise stated (they have the ability to have more than one oxidation number).
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