1 ions ions... are created when an atom gains or loses electrons; are chemical critters that have...
Post on 22-Dec-2015
218 views
TRANSCRIPT
![Page 1: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/1.jpg)
1IonsIons...
• are created when an atom gains or loses electrons;
• are chemical critters that have different numbers of protons and electrons.
![Page 2: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/2.jpg)
2
Cations are ions that have a net + charge => because there are more protons than electrons.
Anions are ions that have a net - charge => because there are more electrons than protons.
![Page 3: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/3.jpg)
3Which atoms gain or lose Which atoms gain or lose electrons?electrons?
• metals characteristically form cations -- they lose electrons.
• non-metals typically form anions -- they gain electrons if they form ions.
![Page 4: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/4.jpg)
4Why does it work this way?
=> there seems to be a natural drive for atoms to gain or lose enough electrons to end up with a filled shell (= energy level) of electrons.
![Page 5: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/5.jpg)
5Examples...
Atoms in Group 1 form cations of +1 charge.
Li has configuration 1s2, 2s1.
Li loses the highest energy electron (from 2s energy):
Li --> Li+ + e-.
Li+ has configuration 1s2.
![Page 6: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/6.jpg)
6Notice that the n =1 shell can Notice that the n =1 shell can have at most 2 electrons in it.have at most 2 electrons in it.
The n = 2 shell can have as The n = 2 shell can have as many as 8 emany as 8 e--. .
Easier for Li atom: lose 1 Easier for Li atom: lose 1 electron and have shell n =1 electron and have shell n =1 filled filled
Harder: gain 7 eHarder: gain 7 e-- to fill the n = 2 to fill the n = 2 shellshell
![Page 7: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/7.jpg)
7Another example: SodiumAnother example: Sodium
Na is 1s2, 2s2, 2p6, 3s1.
Na --> Na+ + e-.
Na+ is 1s2, 2s2, 2p6.
The n =2 energy level is filled.
![Page 8: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/8.jpg)
8In general...
• all elements in Group 1 have the valence configuration ns1.
• all elements in Group 1 lose this single valence electron to form a +1 cation, and
• all +1 cations in Group 1 have a filled (n-1) shell.
![Page 9: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/9.jpg)
9All metals in Group 2 form +2 All metals in Group 2 form +2 cations:cations:
Mg is 1s2, 2s2, 2p6, 3s2.
To get a filled shell, easiest way is lose 2 e- from ns2 orbital:
Mg --> Mg+2 + 2e-.
Mg+2 is 1s2, 2s2, 2p6.
![Page 10: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/10.jpg)
10The most general way to state the conclusion is this:
metals lose enough electrons to metals lose enough electrons to have the same configuration as have the same configuration as the nearest Noble Gasthe nearest Noble Gas.
Mg+2 and Na+ look like Ne.
Li+ looks like He.
![Page 11: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/11.jpg)
11Transition metals (atoms in Groups 3-12) are more complicated...they often form more than one kind of cation. Examples:
Copper, Cu, forms both CuCopper, Cu, forms both Cu+1 +1
and Cuand Cu+2+2..
Iron, Fe, forms FeIron, Fe, forms Fe+2 +2 and Feand Fe+3+3. .
![Page 12: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/12.jpg)
12Guess what? Metals in Group 13 Guess what? Metals in Group 13 lose 3elose 3e-- to form +3 cations: to form +3 cations:
Aluminum has configuration
1s2, 2s2, 2p6, 3s2, 3p1.
Al --> Al+3 + 3e-.
Al+3 is 1s2, 2s2, 2p6.
Al+3 looks like Ne.
![Page 13: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/13.jpg)
13Metals vary in how easily they form cations:
the Ionization Energy (IE) is the energy required to remove the first electron from an atom. Low IE = easily removed electrons.
In any Group, IE decreases going down the column.
![Page 14: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/14.jpg)
14The element with the lowest IE of all the elements is in the bottom of Group 1 (Fr).
Non-metals have very high IE values: it is hard to remove their electrons. Highest IE is for Fluorine.
Instead, non-metals gain Instead, non-metals gain electrons to form ions.electrons to form ions.
![Page 15: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/15.jpg)
15Review: which elements are non-which elements are non-metals? metals? atoms in Groups 14,15,16,17 above the diagonal connecting BBoron & Te Te (Tellerium).
Group 14: C (doesn’t form anion)
Group 15: N, P
Group 16: O, S, Se
Group 17: F, Cl, Br, I
![Page 16: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/16.jpg)
16Can we predict charges of non-metallic anions? YES!
Group 15 elements form -3 Group 15 elements form -3 anions:anions:
N is 1s2, 2s2, 2p3.
N + 3e- --> N-3.
N-3 is 1s2, 2s2, 2p6.
The n = 2 shell is filled like Ne.The n = 2 shell is filled like Ne.
![Page 17: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/17.jpg)
17Group 16 elements form -2 Group 16 elements form -2 anions:anions:
O is 1sO is 1s22, 2s, 2s22, 2p, 2p66..
O + 2eO + 2e-- --> O --> O-2-2..
OO-2 -2 is 1sis 1s22, 2s, 2s22, 2p, 2p66..
The n = 2 shell is filled. OThe n = 2 shell is filled. O-2 -2 looks looks like Ne.like Ne.
![Page 18: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/18.jpg)
18Group 17 elements form -1 Group 17 elements form -1 anions:anions:
Br is [Ar] 4s2, 3d10, 4p5.
Br + 1e- --> Br -.
Br - is [Ar] 4s2, 3d10, 4p6.
Br Br -- looks like Kr looks like Kr.
![Page 19: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/19.jpg)
19Ionic Compounds, Ionic Bonds
An ionic compound forms when An ionic compound forms when cations and anions associate with cations and anions associate with each othereach other: the opposite charges attract.
The electrostatic attraction of The electrostatic attraction of oppositely charged ions is an ionic oppositely charged ions is an ionic bond.bond.
![Page 20: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/20.jpg)
20Formulas for Ionic Compounds
are easy to predict: the total + charge must = the total - charge. Examples:Examples:
NaNa++ and Cl and Cl-- combine 1:1 as NaCl. combine 1:1 as NaCl.
MgMg+2 +2 and Cland Cl-- combine 1:2 as combine 1:2 as MgClMgCl22..
![Page 21: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/21.jpg)
21More examples...
AlAl+3 +3 and Br and Br -- combine 1:3 as AlBr combine 1:3 as AlBr33..
AlAl+3 +3 and Oand O-2 -2 combine 2:3 as Alcombine 2:3 as Al22OO33..
NaNa++ and S and S-2 -2 combine 2:1 as Nacombine 2:1 as Na22S.S.
Note: cation before anion
![Page 22: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/22.jpg)
22Naming Ionic Compoundsis straight-forward:cation name, cation name, anion nameanion name.cation name cation name = name of metal element:NaNa++ is SodiumSodium (ion understood)
MgMg+2 +2 is MagnesiumMagnesium (ditto)
AlAl+3 +3 is AluminumAluminum (ditto)
![Page 23: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/23.jpg)
23For cations that have more than one possible charge:
CuCu++ is Copper(I) Copper(I) [say “copper one”]
CuCu+2 +2 is Copper(II) Copper(II) [say “copper two”]
FeFe+2 +2 is Iron(II)Iron(II)
FeFe+3 +3 is Iron(III)Iron(III)
![Page 24: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/24.jpg)
24anion name anion name = base name of element + ending “ide”
Examples:
ClCl- - is chlorine --> chloridechloride
OO-2 -2 is oxygen --> --> oxideoxide
NN-3 -3 is nitrogen --> nitridenitride
![Page 25: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/25.jpg)
25Putting it all together...
Formula: Is Named:
FeBrFeBr33 iron(III) bromideiron(III) bromide
AlAl22OO33 aluminum oxidealuminum oxide
LiClLiCl lithium chloridelithium chloride
NaNa22SS sodium sulfidesodium sulfide
![Page 26: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/26.jpg)
26
Ionic Solids
• • actually do not exist as actually do not exist as single unitssingle units
• • are large aggregates ofare large aggregates ofcations and anionscations and anions
![Page 27: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/27.jpg)
27
• • each anion and cation may be each anion and cation may be associated with as many as associated with as many as
6 6 ions of opposite chargeions of opposite charge
• • the ions are stacked in the ions are stacked in layers much like fruit layers much like fruit piled up in the grocery storepiled up in the grocery store
![Page 28: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/28.jpg)
28When ionic compounds dissolve in a solvent such as water, the aggregation of cations and anions are broken up---
the compound dissociates into its constituent ions because the cations and anions are more highly attracted to the solvent than to each other.
![Page 29: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/29.jpg)
29Example of NaCl
Cl-
Na+
Cl- Cl-
Cl-
Cl-
Cl-
Na+
Na+
Na+
Na+
Na+
part of a NaCl aggregate
H2Olots!
![Page 30: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/30.jpg)
30Oxygen of H2O solvates cations
Na+ HO H O
H H
H H O H
O
H
![Page 31: 1 Ions Ions... are created when an atom gains or loses electrons; are chemical critters that have different numbers of protons and electrons](https://reader030.vdocuments.mx/reader030/viewer/2022032523/56649d815503460f94a65f8e/html5/thumbnails/31.jpg)
31Hydrogen atoms of water Solvate Anions:
Cl- H-OHHO-H
H
OH
HO
H