bonding teacher note

The attraction between atoms in a molecule or crystalline structure

When elements react atoms must collide

Bond that results when metal atoms release their valence electrons to a pool of electrons shared by all the metal atoms

Holds metals together Results in high conductivity,

malleability, and ductility

Composed of positively and negatively charged atoms Metals on left form compounds with

nonmetals on right Form ionic bonds- a chemical bond

between two ions with opposite charges

EXAMPLE: NaCl

Crystallinesolids

High melting and boiling points Shatter May be water soluble

Electrically neutral because same number of protons and electrons

Gaining or losing 1 or more electrons, atom can be converted into charged particle called ion.

Ion- an atom or group of atoms that has a positive or negative charge

Cations- positive ion, fewer electrons than protons, lose electronsPositive charge on a cation= number of electrons

lostEx. Neutral Mg atom loses 2 electrons Mg2+ ion

Anions- negative ion, more electrons than protons, gain electronsnegative charge on nonmetal anion equals the

number of electrons gainedEx. S gains 2 electrons, sulfide ion S2-

Charge on atom Group 1,2,3 A form charges equal to the

group number (+1, +2, +3) Nonmetals 5, 6, 7 A have negative

charge usually equal to 8 – A group # (-3, -2, -1)

More than one stable ion Examples:

Fe2+ and Fe3+

Cu+ and Cu2+

Many transition metals form 2+ ions.

Octet rule: atoms become stable by having 8 electrons in their outer energy level except some of the smallest atoms which have only 2

Noble gases lack reactivity (stable)(8 electron) Elements stable by achieving configuration of

valence electron of 1 of noble gases. (Share or transfer electrons)

Main group metals react so have an electron configuration like the noble gas before them

Main group nonmetals react so they have an electron configuration like that of the noble gas after them

Dots around atomic symbol represent the number of valence electrons

Write electron dot for Radon (Rn), Lead (Pb), and Xenon (Xe)

Group 1A 2A 3A 4A 5A 6A 7A 8A

# Valence electrons

# e- gained/ lost *

Charge on stable ion

*How many electrons must be gained or lost to satisfy octet rule?

MUST BE ELECTRICALLY NEUTRAL (0) Have the lowest possible number of each

type of atom (Formula unit) Subscripts indicate number of ions Cations always written first and charges are

not included!!

Cation first, anion second Cation of Main Group elements

Simply use the name of element it is formed fromEx: Na+, sodium ionCation of Transition Metals- Use name of the element it is formed from AND

charge designated by a Roman Numeral in ( )- Ex: Fe 3+, Fe (III) ion

AnionReplace ending of name with _____________Examples:

fluoride, chloride, bromide oxide, sulfide, selenide, nitride, phosphide, arsenide

Name the following ionic compounds:MgCl2 FeF3

LiBr ZnO

Al2O3 Na2S

Table 3-8, p.96

Several atoms bound together that collectively have a charge:

3-

Example: phosphate ion

Name the following ions:

NO3-

CN-

OH-

Write the formulas of the following ions: Phosphate ion

Ammonium ion

Permanganate ion

Parentheses may be needed for polyatomic ions

EXAMPLE:aluminum hydroxide ____________________ammonium phosphate___________________sodium sulfate_________________________

p.95a

Magnesium phosphate

1. List Cation first, anion second Ex. NaCl NOT ClNa

2. Don’t write charges of ions Ex. KF NOT K+F-

3. Use parentheses around a polyatomic ion formula if it has a subscript

Ex. Al2(SO4)3 NOT AL2SO4 3

Name the following compounds:

CuO

NaNO3

NH4Cl

Write formulas for the following compounds:

Barium Hydroxide

Copper (II) carbonate

Magnesium bicarbonate