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Ionic Bonding Topic 4.1. http://www.youtube.com/watch?v=xTx_DWboEVs. http://www.youtube.com/watch?v=5IJqPU11ngY. “Review”. Valence electrons electrons in the highest occupied energy level always in the s and p orbitals normally just a draw a circle to represent these two orbitals - PowerPoint PPT Presentation
Citation preview
http://www.youtube.com/watch?v=xTx_DWboEVs
http://www.youtube.com/watch?v=5IJqPU11ngY
Valence electrons› electrons in the highest occupied energy level › always in the s and p orbitals
normally just a draw a circle to represent these two orbitals
› determines the chemical properties of an element› usually the only electrons used in chemical bonds
http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_09/FG09_27-06un.JPG
IB may group levels together and therefore you would see the 3d10 before
the 4s2
IB uses this one
electron dot structures/diagrams are used to show valence electrons› each dot around the element symbol represents a
valence electron
B is 1s2 2s2 2p1;› 2 is the outermost energy level › it contains 3 valence electrons, 2 in the
s and 1 in the p Br is [Ar] 4s2 3d10 4p5
How many valence electrons are present?
http://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/imgper/econfig.gif&imgrefurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html&h=267&w=512&sz=22&tbnid=__EXctBwlG0J:&tbnh=66&tbnw=128&hl=en&start=1&prev=/images%3Fq%3DElectron%2BDot%2BDiagrams%26svnum%3D10%26hl%3Den%26lr%3D
when forming compounds, atoms tend to achieve the electron configuration of a noble gas (ns2np6)› this means their highest energy level will be filled with
8 electrons the easiest way possible› atoms of metallic elements (groups 1,2,3) lose electrons
producing cations (positive ions) Ca becomes Ca2+
› atoms of nonmetallic elements (groups 5,6,7) gain electrons producing anions (negative ions) Cl becomes Cl1-
› group 4 can go either way often loose four electrons and become a 4+ cation
NeNeNNNaNa FF
NaNa+
OO
OO2-
MgMg
MgMg2+
Cations
Anions
NN3- FF1-
...etc.
As it turns out, atoms bond together for a very simple reason: atoms like
to have full valence shells.
1+ 2+ 3-3+ 4+/- 2- 1- 0
› transitional metals can often form more than one cation and therefore charges may vary
iron can be Fe2+ or Fe3+
may fill some orbitals but might not get a noble gas electron configuration
usually composed oppositely charged metallic cations and nonmetallic anions› because of the electrostatic attraction between oppositely
charged particles electro- electricity/electrons static- non-moving (vs. current which is moving charges)
form a compound with overall zero charge
+ cations
- anions
ions must have a difference in electronegativity of 1.7 or greater to form an ionic bond
0.1 – 1.0
1.1 – 1.7
>1.7
0.0 covalent, nonpolar
covalent, slightly polar
covalent, very polar
ionic
electronegativtydifference
probable type of bond
Na “gives” Cl one electron and now both atoms have a full valence shell (electron configuration of a noble gas)
3.9
Na Cl
e–1) 2)
3)
Na+ Cl–
shows the kinds and numbers of atoms in the lowest whole-number ratio of ions in the ionic compound› Na 1+ + Cl 1- NaCl
› Ca 2+ + Cl 1- CaCl2
› Mg 2+ + O 2- MgO
Mg and N? Mg2+, N3-
it takes two nitrogens to combine with three magnesiums› Mg3N2
› magnesium nitride
Na 1+ + F 1- NaF
high melting points can conduct electric currents when melted
or dissolved in water crystalline structure
› repeating arrays of cations and ions› an ionic lattice
cations lose valence electrons and therefore are positively charged› transition metals form more than one cation
with different ionic charges› charge is determined from the # of electrons
lost Fe2+ lost two electrons (the 2 in the 4s) Fe3+ lost three electrons (the 2 in the 4s and 1 in the 3d)
› naming Stock system
a Roman numeral is used to show the charge of the transition metal Fe2+ is iron(II) and Fe+3 is iron(III)
Naming Ions
› anions gain valence electrons and therefore are negatively charged change ending to –ide for the name
composed of more than one atom that form a single unit/ion with a charge› most end with -ite or –ate
the –ite ending indicates one less oxygen than the –ate ending ionic charge is the same for both
Memorize these!NO3
- nitrate
NO2- nitrite
OH- hydroxide
ClO2- chlorite
ClO3- chlorate
SO42- sulfate
SO32- sulfite
CO32- carbonate
HCO32- hydrogen
carbonate (bicarbonate)
PO43- phosphate
NH4+ ammonium
Binary Compounds› cation is written first, followed by the anion
with and –ide ending Cs2O cesium oxide
SrF2 strontium fluoride
CuO copper(II) oxide oxygen is always 2- and therefore copper will be 2+
Cu2O copper(I) oxide oxygen is 2- and therefore needed two copper atoms
with 1+ charge
› SnF2 ? fluorine is always 1- and therefore tin
will be 2+
tin(II) fluoride
› SnS2 ? sulfur is always 2- and therefore tin
will be 4+
tin(IV) sulfide
write symbol of cation and then anion add subscripts to balance the charges
› calcium bromide Ca2+ and Br1- is CaBr2
› potassium sulfide K+1 and S2- is K2S
› iron(III) oxide Fe+3 and O2- is Fe2O3
the ionic charge number of each ion is crossed over and becomes the subscript for the other ion
Fe(NO3)3
Choose the correct name for the compound
1. Iron trinitrate
2. iron(I) nitrate
3. iron(III) nitrite
4. iron(III) nitrate
5. none of the abovenext
problemPolyatomic
IonsPeriodic Chart
sodium chlorite
Choose the correct formula for the compound
1. NaCl
2. NaClO
3. NaClO2
4. Na(ClO)2
5. none of the above
next problem
PrefixesPeriodic Chart
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