Chemistry: Ionic and Molecular Compounds

Valence electrons

electrons in the highest energy level

Ion

an atom that has gained or lost electrons—has a charge

Octet rule

an atom tends to react unless surrounded by 8 valence electrons

Ionic bond

electrostatic attraction between two oppositely charged ions, especially when one atom transfers its electron to another atom

Ionic compound

a compound formed when a metal gives a nonmetal electrons, and so they form an ionic bond

Ionic Compounds Net charge

nuetral

Properties of ionic compounds (NaCl)

brittle, solid, electrolyte

Electrolyte

a compound that can conduct electricity only when dissolved in water or melted

Conduct electricity

need a movable charge

Electrolyte Conduct Electricity in Water Because

the water molecules (H2O) attract the individual ions (H + and O -) so then the ionic bond breaks, and it keeps the ions separate—therefore, there is moveable charge

Solubility

an ionic compound’s ability to dissolve based on the ability for it to be broken down by water molecules

More Solluability

ionic compounds ccomprised of ions with smaller charge

Why Solluability is more for less charge?

Ionic compounds are held by the electrostatic attraction; therefore, the larger charge means stronger pull between ions. So larger charge, more attraction between ions; so harder to be pulled apart by water

Ionic compounds colorful

transition metals

Elements that make ionic compounds orange and brown

Fe

Elements that make ionic compounds green and blue

Cu

Elements that are colorless

group 1 and 2

Why do metals have color? Metals often have partially filled d orbitals (a energy jumpt that corresponds to the visible light spectrum)

Roman numeral for ionic compounds

the positive charge of transition metal ion

Transition metals exceptions why

only form 1 ion since their electrion configuration are very stable after specific loss of electrons

Transition metals exceptions

silver (Ag+), Zinc (Zn2+), aluminum (Al3+)

Polyatomic ions

group of ions with a charge

Polyatomic ions combined by

bonded by covalent bonds

Halogens and polyatomic ions

You can apply similar formats to other elements

Ionic compounds and polyatomic ions

use parentheses for the polyatomic ions with multiple, and typically the non-metal

Nick the camel ate clam supper in Phoenix

Nitrate

(NO4)3-

Carbonate

(CO3)2-

Chlorate

(Cl3)-

Sulfate

(SO4)2-

Phosphate

(PO4)3-

Hydroxide

OH-

Ammonium

NH4+

Acetate

CH3COO-

Cyanide

CN-

Permanganate

MnO4-

Peroxide

(O2)2-

-ide

normal ionic compound

-ate

polyatomic ion

-ite

minus O of polyatomic ion

Hypo–ite

minus 2O of polyatomic ion

Per–ate

add O of polyatomic ion

bi-

add H of polyatomic ion

Di-

add 2H of polyatomic ion

Molecular compounds

made up of nonmetals held by covalent bonds

Molecular compounds structure

composed of individual molecules

Covalent bonds

a chemical bond formed when two atoms share one or more pairs of electrons

Properties of molecular compounds

any state of matter, no conductivity, generally soft and brittle

Molecular naming

prefix-element prefix-element-ide

1

mono

2

di

3

tri

4

tetr(a)

5

pent(a)

6

hex(a)

7

hept(a)

8

oct

9

non(a)

10

dec(a)

Water

H2O (water)

Ammonia

NH3 (gas)

Methane

CH4 (gas)

Acids

a substance that releases hydrogen ions (H+) when dissolved in water

Acid requirement

must be neutral

Acetic acid

CH3COOH

Hydrochloric acid

HCl

Nitric acid

HNO3

Carbonic acid

H2CO3

Molecular Compound exception to the octet rule

period 3 and below in range Si to Ci

Single bond

a covalent bond consisting of 1 pair of shared electrons

Double bond

a covalent bond consisting of 2 pairs of shared electrons

Triple bond

a covalent bond consisting of 3 pairs of shared electrons

of bonds depend on

of electrons for octet

Best Lewis structure

least formal charges and the most electronegative atom has the negative charge

Electronegativity

how much an atom attracts electrons

Why Electronegativty

forming bond releases energy, less energy, more stable

Electronegativity top to bottom

decrease, drastic energy level change, less effective nucleus charge, and more shielding

Electronegativity left to right

increase, size smaller, more effective nucleus charge, closer to full valence shell

Same Electronegativity Special

C and H—nonpolar bond

H and metal Electronegativity

H is more electronegative

H and nonmetal Electronegativity

nonmetal is more electronegative

Formal charge

valence electrons - bonding electrons + nonbonding

Formal charge discrepancy

formal charges are not precise for some atoms are more electronegative than the other. Such that it attracts more of the electron than the other, therefore, its not precisely an integer formal charge

Resonance structures

different ways to draw lewis structures for a molecule as one alone is not accurate on positioning

Discovery of composite dot structure

in solid phase, scientist shined light to find structure and found all same length—assumption it was uneven but found shared

Why resonance

helps diffuse charge by spreading the charge—which makes it more stable

Resonance is common in

polyatomic ions because it has charge

Composite Dot structures

average of all resonance structures

Bond energy

amount of energy to break a bond

Bond length depends

on the elements of the bond

Single bond —> Double bond

doubl bond energy

Comparing a shorter bond to a longer bond

a single bond has more attr

a single bond has less bond energy than a double bond, therefore, the one with the greater charge

Valence shell electron pair repuslion

molecule assume the shape to get electrons as far away from each other as possible