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 that requires the least amount of energy

› cations atoms of metallic elements (groups 1-14) lose

electrons producing cations (positive ions) the term oxidized (O.I.L – Oxidized Is Losing) is used

to say it lost an electron example- Ca becomes Ca2+

› anions atoms of nonmetallic elements (groups 15,

16, 17) gain electrons producing anions (negative ions) the term reduced (R.I.G.) – Reduction Is

Gaining) is used to say it gained an electron example- Cl becomes Cl1-

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 that

have full valence shells are more stable than those that don’t‘.

1+ 2+ 3-3+ 4+/- 2- 1- 0

› some transitional metals can often form more than one cation and therefore charges may vary

some orbitals get filled but might not get a noble gas electron configuration

iron can be Fe2+ or Fe3+ (you don’t have to memorize this)

these always have the same charge Sc3+, Zn2+, Cd2+, Ag1+ (you do have to memorize these)

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)

+ cations

- anions

forms a compound with overall zero charge› (+ and -) need to cancel out

referred to as formula units, not a molecule, that is a term used only for covalently bonds which is something different

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 and boiling points › takes a lot of energy to break apart the electrostatic

forces between cations and anions

crystalline structure› repeating arrays of cations and ions› an ionic lattice

volatility- how easily a substance turns into a gas› very low as electrostatic forces between cations

and anions is very strong

electrical conductivity› can conduct electric currents when melted or dissolved

in water because cations and anions are free moving instead in a lattice

solubility› will dissolve in other polar solvents such as water

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

-1 nitrate

NO2-1 nitrite

OH-1 hydroxide

ClO2-1 chlorite

ClO3-1 chlorate

HCO3-1 hydrogencarbonat

e (bicarbonate)

SO42- sulfate

SO32- sulfite

CO3 2- carbonate

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