Chemistry Unit 4

Metal + Non Metal

Transfer of Electron

Ionic Compounds

Attraction of Oppositely Charged Ions

Ionic Compounds

1+ Metal

Attraction between free floating valance electrons and positively charged metal ions

Metallic Bonds

1+ nonmetal or metalloid

Share Electrons

Molecules

Attraction between shared electrons and the positively charged nuclei of the atoms

Covalent Bonds

Molecule

the neutral group of atoms joined together by covalent bond

Molecular Formula

chemical formula of a molecular compound

represents of actual # of atoms not necessarily the lowest ratio

does not show atoms structure

Diatomic Molecule

Molecule consists of 2 atoms of the same element

Molecule Compound

2+ atoms of different compounds

Diatomic elements

• Hydrogen

• Nitrogen

• Oxygen

• Fluorine

• Chlorine

• Bromine

• Iodine

lone pairs/ nonbonding pairs

unshared pairs of electrons

Covalent bonds are held together by

attraction between the negatively charged shared electrons and positively charged nuclei of the two atoms

Molecular formula what is listed first

most metallic is listed first

if in the same group, bottom one

Hydrogen exceptions to formula

CH
NH

PH

Bond dissociation energy

the energy required to break the covalently bonded atoms

larger energy the stronger bond

Triple Bonds vs Single

(highest dissociative energy, strongest covalent bonds, shortest bonds) vs (lowest dissociative energy, weakest covalent bonds, longest bonds)

Number prefixes

1- mono

2- di

3- tri

4- tetra

5- penta

6- hexa

7- hepta

8- octa

9- nona

10- deca

Naming Binary covalent compounds

If its one element diatomic molecule its named

just as element name

Spelling rules for naming diatomic compounds

oo- only one o

ao- just o

Chemical formula for tetraohosphorus trisulfide

P2S3

Drawing Lewis Structure Steps

PRACTICE

1.) Find total number of valance (add or subtract for ions)

2.) Put the least electronegative in the center (hydrogen goes outside)

3.) Put 2 valance electrons between atoms to bond

4.) use remaining electrons to complete the octet on outside atoms

5.) use remaining to complete central atom octet (Hydrogen only needs 2)

6.) if you run out: move from outer electrons for double or triple bonds

7.) replace shared electrons with dashes

If odd number of valance electrons

place the unpaired electron on the central atom

Which atom has an incomplete octet

boron (B)

Expanded octet

(only happens when central is from period 3+)

excess electrons go on central atom

(phosphorous or sulfur expand to 10 or 12)

VSEPR

used to determine the 3-D shape of molecules or ions'

the region of highest electron densitiy (electron domains) will arrange as far apart as possible around the central atom

Linear

2 electron domains

0 none bonding or lone

trigonal planar

3 electron domains

0 non bonding or lone

bent

3 or 4 domains

1 or 2 non bonding/lone

tetrahedral

4 domains

0 lone pairs

trigonal pyramidal

4 domains

1 none bonding

trigonal bipyramidal

5 domains

0 non bonding

seesaw

5 domains

1 non bonding

T shaped

5 or 6 domains

2 or 3 non bonding

octahedral

6 domains

0 non bonding

square pyramidal

6 domains

1 nonbonding

Square Planar

6 domains

2 non bonding

Molecular geometries are or are not always the same as VSPER

ARE NOT

Molecular geometry is determined by atoms bonded to the central atom not

the lone pairs

0 vs 1+ lone pairs makes the molecular geometry

the same vs different from the VSPER

Bonding pair of covalent are pulled between

the nuclei of the atoms sharing electrons

Covalent bonds involve

the sharing of electrons

Non polar coavlent bond

occurs when bonding electrons are shared equally between the two

Polar covalent bond

occurs when bonding electrons are shared unequally between two atoms

Ionic Bonds

no sharing of electrons between ions

Non polar covalent electronegativity difference range

0.0-0.4

polar covalent electronegativity difference range

0.5-1.9

ionic electronegativity difference range

2+

In polar covalent the more electronegative atom attracts electrons more strongly and gains a slightly

negative charge

In polar covalent bonds, less electronegative atoms have

a slightly positive charge

the higher the electronegativity value

the greater the ability of an atom to attract electrons to itself

Partial charges can be shown as

clouds of electron density

an arrow poinitng towards the more electronegaitive atom

Electronegativity can be used to identify

polar bonds in a molecule

Naming conventions to not bend to

electronegativity

polar molecule

a molecule in which one end of the molecule is slightly more positive or negative

Wheter or not a molecule is polar depends on the

bond polarity and molecular shape

Polar molecules contain/ are

1+ polar covalent bond

asymmetric (Contain lone pairs of electrons on the central atoms or habe atoms with different electronegatibity bonded to the.centrl atom)

how to determine if a molecule polar with 2+ atoms

draw lewis structure

does it have any polar bonds (determine w/ electron negativity)

does it have any lone pairs of electrons or different atoms on the central (if no than nonpolar, if yes polar)

Covalent compounds structures

no crystalline

generally indivual molecules

Network covalent compounds

exception from general structures of covalent

3-D lattice “network of strong bonds”

different properties like diamonds

structures of metals vs ionic

organize crystaliane sea of electrons free valance

vs

organized crystalline lattice

3-d repeating

Intramolecular forces

the forces that hold atoms together within the molecule or compound

(metallic, ionic, or covalent bonds)

comparsion of melting points

high metal and ionic compounds

low covalent

very high network covalent

comparsion of boiling points

high metal and ionic

low covalent

very high network covalent compounds

comparisions of conductivity

metals as solid

ionic compounds melted or dissolved

covalent compounds dont

network covalent dont