Download presentation
Presentation is loading. Please wait.
Published byCorey Patterson Modified over 9 years ago
1
NOTES: 7.1 - Ions
2
Valence Electrons: ● Knowing electron configurations is important because the number of valence electrons determines the chemical properties of an element. ● Valence Electrons: The e- in the highest occupied energy level of an element’s atoms.
4
Valence Electrons: ● All elements in a particular group or family have the same number of valence electrons (and this number is equal to the group number of that element) Examples: ● Group 1 elements (Na, K, Li, H): 1 valence e-. ● Group 2 elements (Mg, Ca, Be): 2 valence e-. ● Group 17 (7A) elements (Cl, F, Br): 7 valence e-.
6
LEWIS STRUCTURES: ● Electron dot structures show the valence electrons as dots around the element’s symbol: ● Li ● B ● Si ● N ● O ● F ● Ne
7
LEWIS STRUCTURES: ● Electron dot structures show the valence electrons as dots around the element’s symbol: ● Li ● B ● Si ● N ● O ● F ● Ne
9
Which elements form ionic compounds and which elements form covalent (molecular) compounds?? General Rule of Thumb: metal + nonmetal = IONIC metal + polyatomic anion = IONIC polyatomic cation + anion = IONIC nonmetal + nonmetal(s) = COVALENT
10
Why are ionic compounds so stable? ● IONIC BONDS: -metal plus a nonmetal -cations plus anions -opposite charges attract ● Examples: Na + and Cl - form NaCl Al 3+ and Br - form AlBr 3
11
Ionic Bonds: Isn’t it ionic that opposites attract?
12
OCTET RULE: ● Noble gas atoms are very stable; they have stable electron configurations. In forming compounds, atoms make adjustments to achieve the lowest possible (or most stable) energy. ● Octet rule: atoms react by changing the number of electrons so as to acquire the stable electron structure of a noble gas.
13
Formation of Cations and Anions ● can be predicted using the octet rule (not always followed, but a good general rule to follow for the representative elements) -full outer energy level -eight electrons (s 2 p 6 ) **explains formation of both cations and anions
14
CATIONS: ● Na: 1s 2 2s 2 2p 6 3s 1 ● Na + : ● Mg: 1s 2 2s 2 2p 6 3s 2 ● Mg 2+ :
15
CATIONS: ● Na: 1s 2 2s 2 2p 6 3s 1 ● Na + : 1s 2 2s 2 2p 6 ● Mg: 1s 2 2s 2 2p 6 3s 2 ● Mg 2+ : 1s 2 2s 2 2p 6
16
OCTET RULE: ● Atoms of METALS obey this rule by losing electrons. Na: Na + :
17
OCTET RULE: ● Atoms of METALS obey this rule by losing electrons. Na: Na + :
18
ANIONS: ● Cl: 1s 2 2s 2 2p 6 3s 2 3p 5 ● Cl - : ● O:1s 2 2s 2 2p 4 ● O 2- :
19
ANIONS: ● Cl: 1s 2 2s 2 2p 6 3s 2 3p 5 ● Cl - : 1s 2 2s 2 2p 6 3s 2 3p 6 ● O: 1s 2 2s 2 2p 4 ● O 2- : 1s 2 2s 2 2p 6
20
OCTET RULE: ● Atoms of NONMETALS obey this rule by gaining electrons. Cl: Cl - :
21
OCTET RULE: ● Atoms of NONMETALS obey this rule by gaining electrons. Cl: Cl - :
22
OCTET RULE: ● Transition metals are exceptions to this rule. Example: silver (Ag) Ag + By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)
23
OCTET RULE: ● Transition metals are exceptions to this rule. Example: silver (Ag) Ag + By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.