11/17 notes

Question 1

electrons are always what

Answer 1

moving around nucleus

Question 2

room temperatuer and oressure are what type of conditions

Answer 2

standard

Question 3

pressure standard =

Answer 3

1 atm

Question 4

room temp is

Answer 4

25C or 285K

Question 5

what do all molcuels have

Answer 5

can form alrger and longer lasting temp diploes therefore stronger and attractive forced

Question 6

forces get stronger with

Answer 6

molcule size

Question 7

strength of diploes for compact structure

Answer 7

weaker dipoes

Question 8

where do permanent diopole forces exist

Answer 8

exist in molecules that have net dipoles

Question 9

is permanebt dipole attraction is stronger than temporary dipole attraction

Answer 9

yes

Question 10

the larger the net dipole the _____the attraction

Answer 10

stronger

Question 11

Describe in detail why even nonpolar molecules have attractive intermolecular forces.

Answer 11

because of temporary dipoles that occur in nonpoalr molecules when electrond constantly orbit the nuceus occupy a similar location by chance

Question 12

why is a temporary dipole called temporary

Answer 12

called temporary dipoles because electronsare always moving

Question 13

Why do all atoms and molecules have temporary dipole forces?

Answer 13

all atoms have temporary dipoles because electrond are always moving around the nucleus

Question 14

What factors increase the size of temporary dipole forces? W

Answer 14

the size of tenporary dipole is caused by polarizability: valnce electrons are not held as tightly, can form larger and longer lasting temp dipoles therefore stronger attractive forces

Question 15

What intermolecular forces do polar molecules have?

Answer 15

permanent dipole IMF

Question 16

How does the size of the molecule’s dipole impact the strength of the intermolecular force? And
how would this affect its melting and boiling points?

Answer 16

the larger the net dipole the stronger the attraction, the larger the et dipole the hgh the melting and boiling point

Question 17

What is a hydrogen bond?

Answer 17

exists in molecues with x-h binds where x=N,O,F
-anything with H has a net dipole

Question 18

How does the strength of hydrogen bonds compare to permanent dipole forces and temporary
dipole forces?

Answer 18

h bonds are stronger than dipole attractions

Question 19

Why are most small covalent molecules gases at room temperature and pressure? Why might
some of them be liquids?

Answer 19

most small covalent molecule gases are at room temp and pressure b/c IMF of attractio between mokecukes are weak and easy to overcome. Very little energy is required to overcome these forces, therefore simple molecules are liquids + gases at room temp

Question 20

Why does increasing molecular size increase the boiling point?

Answer 20

b/c IMF of attraction betwewen molecules is stronger and harder to overcome. More energy is required to overcome these forces

Question 21

Why are most large covalent molecules solids at room temperature and pressure?

Answer 21

moelcules have so many electrons. the resulting dispersion forces between these molecules makes them assume the solid phase at normal temperatures

Question 22

How do intermolecular forces strengths compare with covalent bond strengths?

Answer 22

IMF forces are genrlly weaer than covalent bonds
(Note that the covalent bond is intramolecular or within a molecule, while intermolecular
attractive forces are between discrete molecules.)

Question 23

Given a chemical substance, what type of intermolecular forces does it have?

Answer 23

ion dipole forces are positively charged end of a polar molcule such as H2O is attracted to negative ions