Electronegativity And Polarity

Question 1

What is electronegativity?

Answer 1

The tendency of an atom in a covalent bond or molecule to attract molecules ina. Covalent bond to itself

Question 2

WHEN DO you get electronegativity

Answer 2

When bonded atoms are different elements - nuclear charges are different the atoms may be different in sizes and the shared pair of electrons may be closer to ONE nucleus than another

Question 3

Factors affecting electronegativity

Answer 3

Shielding- more shells decreases the electron negativity
Protons- more protons means a higher electron negativity
Atomic radius

Question 4

Most electronegative elements?

Answer 4

F, N, O and CL

Question 5

As you go down a group, what does the electronegativity co?

Answer 5

It DECREASES because the distance between the nucleus and the outer electrons increases and the shielding of inner she’ll electrons increases

Question 6

What happens tp electronegativity as you go across the period

Answer 6

INCREASES as the umber of protons increases and the atomic radius decreases, because the electrons in the same she’ll are pu;;ed on ,pre

Question 7

Non polar bonds

Answer 7

The bonded electron pair is SHARED EQUALLY between the bonded atoms
A bond will be non polar when..
- the bonded atoms are the same
-the bonded atoms have the same or similar electronegativity
- same elements- PURE COVALENT BODN

Question 8

POALR BONDS

Answer 8

Bonded electrons are shared unusually between the bonded atoms
When bonded atoms are different- have different electronegativity values- pure covalent bonds
Between ionic and non polar covalent

Question 9

Electronegativity differnences for non polar covalent, polar covalent and ionic ?

Answer 9

<0.4- non polar
0.4-1.8- polar
>1.8 - ionic

Question 10

How is electronegativity measured

Answer 10

PAULING scale

Question 11

Symmetry - covalent bonding

Answer 11

If polar bonds are arranged symmetrically partial charges/individual dipoles
CANCEL OUT AND ITS NON POLAR

Question 12

INTERMOLELAR forces?

Answer 12

Weak interactions between dipoles of DIFFERNENT molecules

Question 13

3 categories of intermolecular forces?

Answer 13

VAN DER WAAL?

• induced dipole dipole interactions
• permanent dipole dipole interactions
• hydorgen bonding

Question 14

What are intermolecular forces responsible for?

Answer 14

Boiling and melting point

COVALENT BONDING - IDENTITIY OF CHEMICAL REACTIONS OF MOLCUELS

Question 15

BONDING- intra molecular

Answer 15

Within molecules and structures
Ionic
Covalent
Metallic

Question 16

Intermolecular- between molecules

Answer 16

Broken to melt/boil covalent substances

Question 17

Permenant dipole dipole interactions

Answer 17

Between permenant dipoles in POLAR molecules
Stronger than induced dipole - dipole interactions = compounds have higher boiling points
Polar molecules have a permenant dipole

Question 18

INDUCED DIPOLE DIPOLE FORCES

Answer 18

Occur between all simple covalent molecules and separate atoms in noble gases
In any molecule the electrons are moving constantly and randomly
As this appends, electron density can fluctuate + parts of the molecule has become more or less negative ie small temporary or transient dipoles form
These temporary dipoles can cause dipoles to form in neighbouring molecules

Question 19

factors affecting induced dipole dipole interactions

Answer 19

More electrons ( main factor ) 
Shape

Question 20

More electrons - effect on size of induced dipole, dipole interactions

Answer 20

• larger the instances adn induced dipoles
• greater the induced dipole-dipole interactions
• stronger the attractive forces between molecules

LARGER INDUCED DIPOLES = MORE ENERGY TO OVERCOME INTERMOLECULAR FORCES= INCREASES THE BOILING POINT

Question 21

Shape - effect on size of induced dipole dipole interactions

Answer 21

The shape of the molecule can have an effect on size of the induced dipole dipole interactions forces
long chain alkanes have a larger surface area if contact between molecules for induced dipole , dipole interactions to form than compared to spherical branched alkalies

Question 22

Strength of intermolecular forces ?

Answer 22

H bonding - 10-40
Permenant D_D= 3-25
INDUCED D_D= 1-10

Question 23

Simple molecular substances

Answer 23

Made up of simple molecules
Small units containing definite number of atoms with a definite molecular formula e.g. Neon. Hydrogen. Water . Co2
Solid - form regular structure called a simple molecular lattice, atoms he’d in place by WEAK IMF, atoms within molecule - strong covalent bonds

Question 24

Hydrogen bonding ?

Answer 24

Strong dipole- dipole interaction between an electronegative atom with lone pair of electrons e.g. Oxygen. , nitrogen or fluorine ( FON)

A hydorgen atom attatched to an electronegative atom e.g. H-O , H_N or H_F

Eg h-n ——–H -N

Question 25

Are hydrogen bonds STrong?

Answer 25

STRONGEST IMF

Question 26

Properties of water

Answer 26

Without h bonds = -75 BP and gas at room temp
High melting and boiling point
When water boils- H bods break completely
When ice lattice breaks- rigid arrangement of H bonds is broken
Solid ice- less dense than liquid water, water molecules in ice - further apart than water , 2 lone pairs + 2 h atoms - each h20 can from 4 H bonds . Form a tetrahedral lattice with mSNY holes - 180 bond angle about the H atom