Intermolecular Forces+condensed Matter

Question 1

What are intramolecular forces

Answer 1

They keep together the atoms within the molecules and ionic compounds(bonds)

Question 2

What are intermolecular forces

Answer 2

Interactions that occur between the molecules. They are responsible for formation of liquid and solid and state in ehich substance exist at a particular temperature and pressure

Question 3

How are condensed phases held together

Answer 3

By attractive interactions between the molecules

Question 4

Are intermolecular forces stronger than covalent bonds

Answer 4

No

Question 5

Types of intramolecular forces

Answer 5

•ion-ion interactions
(These 2 are van der waals interactions)
•Dipole-dipole int.
•dispersion forces(London)-(instant)dipole-induced dipole
—–
•hydrogen bond->dipole-dipole

Question 6

Explain polarity in diatomic molecule

Answer 6

If 2 elements are of the same electronegativity that compound in non-polar. When two elements have different electronegativity, the dipole is created where one side of the molecule is negatively charged(б-) and other positively(б+). Direction of molecular dipole is represented by the arrow that goes from б- to б+

Question 7

What is polar molecule

Answer 7

Any molecule with non-zero dipole moment. The units of dipole moment are debyes, D

Question 8

Explain polarity in polyatomic molecules

Answer 8

The dipole moments can cances each other out(ex. б- ,б+,б-) because direction of the dipole is in the center and they cancel each other. While б+,б-,б+ doesnt cancel each other because it goes into different directions

Question 9

What does determine that polyatomic molecule is polar or not

Answer 9

It’s shape and whether the polarities of individual bonds cancel out

Question 10

What kind of interactions do molecules with the dipole moment have

Answer 10

Electrostatic

Question 11

How do molevules in liquids align

Answer 11

They want to maximize attraction forces

Question 12

What kind of attractive interactions exist in non-polar substances

Answer 12

Dispersion/London forces

Question 13

Explain how temporary dipole is created

Answer 13

When a molecule with a dipole approaches molecule without one, it induces movement of e- causing temporary dipole

Question 14

What is measured by polarizability

Answer 14

The strength of induced dipole. It also explains how easily it is to move electron cloud of non polar molecule around

Question 15

What increases intersction between instantenuous dipoles

Answer 15

Molar mass(more e-) and shape(higher in long and non symmetric molecules)

Question 16

Explain hydrogen bond

Answer 16

H attracted to O,N,F is attracted to electronegative atom od adjacent molecule

Question 17

What causes boiling point to be higher

Answer 17

Van der waals forces(higher they are(higher molecular mass is)higher the boiling point. Exception are liquids that form hydrogen bonds, their boiling points are higher than excepted taking into accaunt molecular mass

Question 18

What is stronger, Van der Waals or hydrogen bonds

Answer 18

Hydrogen

Question 19

Can carbon form hydrogen bonds

Answer 19

No

Question 20

What attractions are broken when the phase changes happen

Answer 20

Intermolecular

Question 21

What do we take into accaunt when classifying solids

Answer 21

Bonds

Question 22

Classify solids

Answer 22

•ionic solids- electrostatic interaction between oppositely charged ions hold it together. They have high melting and boiling points. They conduct electricity in the solution and in the liquid phase
•molecular solids-they are kept together through intermolecular forces. Low melting and boiling points. They are poor electrical conductors
•metals-cations kept together through cloud of delocalized e-. Wide range of melting points,conduct electricity and heat
•covalent netword solid-infinite structures where non-metal elements are linked through covalent bonds. High melting and bpiling points

Question 23

Explain formation of metal solids

Answer 23

Metals have low ionization enthlapies so they lose their valence e-. The free electron model considers the lattice as being made up of metal ions, surrounded by a sea of delocalized e-.

Question 24

Explain how metals conduct electricity

Answer 24

Normally, e- move into random direction but then potential difference is applied, e- move from high to low potential which gives rise to a current. Thats why they conduct electrcity

Question 25

What does malleable and ductile mean

Answer 25

Malleable- hammered into sheets
Ductile- drawn into wires

Question 26

Ehy are metals malleable and ductile

Answer 26

Planes of metal can slip past one another when force is applied

Question 27

Formula for density

Answer 27

р=m/V. [g/cm³]

Question 28

What properties in a liquid do intermolecular forces determine

Answer 28

•surface tension
•viscosity
•vapour pressure

Question 29

What is viscosity

Answer 29

Resistance of a fluid to flow. The stronger the intermolecular forces–> higher viscosity. It decreases with temperature

Question 30

Explain surface tension in a liquid

Answer 30

Liquids tend to take the lowest surface tension as possible. It results from the greater attraction between liquid molecules than with molecules in the air.

Question 31

Explain vapoud pressure

Answer 31

It’s the pressure of vapoud when liquid is boiled. If we close the container, vapoud and liquid come to equilibrium and then vp is called the saturated vp

Question 32

What are volatile solids and liquids

Answer 32

They have high vapour pressure

Question 33

Is solid form of water more or less dense than the liquid one

Answer 33

Less