Ions and valence electrons
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Ions and valence electrons

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Ions. Formed by gain or loss of electronsWhen positive, the name of the ion is the same as that of the elementWhen negative, the name of the ion is the root name of the element plus
Ions and valence electrons

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1. Ions and valence electrons Section 7.1

2. Ions Formed by gain or loss of electrons When positive, the name of the ion is the same as that of the element When negative, the name of the ion is the root name of the element plus ? ide Valence electrons- are the only electrons gained or lost.

3. Valence electrons Valence electrons are the outer shell electrons; Electrons in the highest occupied energy level They determine the chemical properties of an element They are farthest from the nucleus and therefore easiest to remove

4. Valence Electrons For the representative groups 1A-7A and the noble gases, finding the number of valence electrons is easy! Valence electrons are the same as the group number Finding valence electrons for the transition metals requires finding the electron configuration Look at the electrons in the highest principle energy level

5. Valence Electrons Electron dot structures are diagrams that show valence electrons as dots.

6. Stability of atoms Octet Rule- Atoms are stable if they have 8 valence electrons, a noble gas configuration they must gain, lose or share electrons to become stable Exceptions for ions: Hydrogen, Beryllium, Lithium, and Helium stable with 2 (full outer shell of electrons)

7. Becoming Stable Atoms of metals tend to lose their valence electrons, leaving a complete octet in the next-lowest energy level. Form Cations Atoms of some non-metals tend to gain electrons or to share electrons with another nonmetal to achieve a complete octet. Form Anions

8. Forming cations The most common cations are those produced by the loss of valence electrons from metal atoms. You can represent the electron loss, or ionization, of the sodium atom by drawing the complete electron configuration of the atom and of the ion formed. Notice just the valence electron is lost. .

9. Formation of Cations The electron configuration of the sodium ion is the same as that of a neon atom.

10. Formation of Cations Using electron dot structures, you can show the ionization more simply.

11. Formation of Cations The sodium atoms in a sodium-vapor lamp ionize to form sodium cations. The sodium atoms in a sodium-vapor lamp ionize to form sodium cations (Na+). Applying Concepts How many electrons are in the highest occupied energy level of Na+? The sodium atoms in a sodium-vapor lamp ionize to form sodium cations (Na+). Applying Concepts How many electrons are in the highest occupied energy level of Na+?

12. Formation of Cations A magnesium atom attains the electron configuration of neon by losing both valence electrons. The loss of valence electrons produces a magnesium cation with a charge of 2+.

13. Formation of Cations Walnuts are a good dietary source of magnesium. Magnesium ions (Mg2+) aid in digestive processes. Walnuts are a good dietary source of magnesium. Magnesium ions (Mg2+) aid in digestive processes. Walnuts are a good dietary source of magnesium. Magnesium ions (Mg2+) aid in digestive processes.

14. Formation of Cations Cations of Group 1A elements always have a charge of 1+. Cations of group 2A elements always have a charge of 2+. Cations of Group 1A elements have a charge of 1+. Cations of Group 2A elements have a charge of 2+. Cations of Group 1A elements have a charge of 1+. Cations of Group 2A elements have a charge of 2+.

15. Formation of Cations Pseudo-noble gas configuration behaves like a noble gas configuration but consists of ns2(n-1)d10np6 The electron configuration is similar to Argon but has 10 more electrons in the d sublevel. The s and p sublevels still determine stability.

16. Formation of Anions The gain of negatively charged electrons by a neutral atom produces an anion. An anion is an atom or a group of atoms with a negative charge. The name of an anion typically ends in -ide. Example: oxygen would become oxide Sulfur would become sulfide Chlorine would become chloride

17. Formation of Anions The figure shows the symbols of anions formed by some elements in Groups 5A, 6A, and 7A. Atoms of nonmetals and metalloids form anions by gaining enough valence electrons to attain the electron configuration of the nearest noble gas. Interpreting Diagrams In which group of the periodic table do the elements bromine and iodine belong? Atoms of nonmetals and metalloids form anions by gaining enough valence electrons to attain the electron configuration of the nearest noble gas. Interpreting Diagrams In which group of the periodic table do the elements bromine and iodine belong?

18. Formation of Anions A gain of one electron gives chlorine an octet and converts a chlorine atom into a chloride ion. It has the same electron configuration as the noble gas argon.

19. Formation of Anions Both a chloride ion and the argon atom have an octet of electrons in their highest occupied energy levels.

20. Formation of Anions In this equation, each dot in the electron dot structure represents an electron in the valence shell in the electron configuration diagram.

21. Formation of Anions The negatively charged ions in seawater?the anions?are mostly chloride ions. The six most abundant ions in seawater are chloride (Cl? ), sulfate (SO42?), sodium (Na+), magnesium (Mg2+), calcium (Ca2+), and potassium (K+). The six most abundant ions in seawater are chloride (Cl? ), sulfate (SO42?), sodium (Na+), magnesium (Mg2+), calcium (Ca2+), and potassium (K+).

22. Formation of Anions The ions that are produced when atoms of chlorine and other halogens gain electrons are called halide ions. All halogen atoms have seven valence electrons. All halogen atoms need to gain only one electron to achieve the electron configuration of a noble gas.

23. Formation of Anions Oxygen is in Group 6A.

24. How to predict the charge First remember that an atom is stable with 8 valence electrons Metals tend to lose electrons to get charges of 1+, 2+, and 3+ Nonmetals tend to gain electrons to get charges of 1-, 2-, and 3- The max charge is USUALLY + or - 3

25. Writing electron configurations for ions Write the electron configuration as usual Remove the correct number of valence electrons to make the ion stable or to match the charge if you are given the charge For transition metals, you may have to remove electrons from the d sublevel to match a given charge

26. Unusual or Multiple charges Lead and Tin both have charges of 2+ or 4+ Iron 3+ or 2+ Copper 1+ or 2+ Manganese 1+, 2+, 5+, 7+ Zinc 2+ only Silver 1+ only Cadmium 2+ only

27. 7.1 Section Quiz. 1. How many valence electrons are there in an atom of oxygen? 2 4 6 8

28. 7.1 Section Quiz. 2. Atoms that tend to gain a noble gas configuration by losing valence electrons are metals. nonmetals. noble gases. representative elements.

29. 3. When a magnesium atom forms a cation, it does so by losing two electrons. gaining two electrons. losing one electron. gaining one electron. 7.1 Section Quiz.

30. 4. When a bromine atom forms an anion, it does so by losing two electrons. gaining two electrons. losing one electron. gaining one electron 7.1 Section Quiz.


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