Intra/Intermolecular forces

Question 1

What are the two kinds of forces that operate in a molecule?

Answer 1

Intramolecular and intermolecular forces

Question 2

Define intramolecular forces

Answer 2

Forces that hold atoms together within a molecule

Question 3

Define intermolecular forces

Answer 3

Forces that exist between molecules

Question 4

What is an ionic bond?

Answer 4

A bond formed by the complete transfer of valence electron(s) between atoms, generating two oppositely charged ions

Question 5

What happens to electrons in ionic bonds?

Answer 5

The metal loses electrons to become a positively charged cation, while the nonmetal accepts those electrons to become a negatively charged anion

Question 6

Define electronegativity

Answer 6

The affinity or desire for electrons.
OR
capacity of receiving electrons

Question 7

What is a covalent bond?

Answer 7

A bond formed between atoms that have similar electronegativities, sharing electrons to achieve octet configuration

Question 8

What are the two types of covalent bonds?

Answer 8

Polar and nonpolar covalent bonds

Question 9

Define nonpolar covalent bond

Answer 9

A bond formed between same atoms or atoms with very similar electronegativities, with a difference less than 0.5 (they “pull” each other the same)

Question 10

Define polar covalent bond

Answer 10

A bond formed when atoms of slightly different electronegativities (slightly + or -) share electrons, with a difference between 0.5 and 1.9 (one “pulls” the other one more)

Question 11

What is metallic bonding?

Answer 11

A type of covalent bonding occurring between atoms of metals, where valence electrons are free to move through the lattice

Question 12

What is the ‘sea of electrons’ in metallic bonding?

Answer 12

Mobile electrons that move freely and cause the attraction to fixed positively charged metal ions

Question 13

How do intermolecular forces affect physical properties?

Answer 13

They determine boiling point, melting point, density, and enthalpies of fusion and vaporization

Question 14

What is the relationship between boiling point and intermolecular attractions?

Answer 14

Lower boiling point indicates weaker intermolecular attractions, while higher boiling point indicates stronger attractions

Question 15

What are dipole-dipole interactions?

Answer 15

Forces of attraction enabling two polar molecules to attract one another (slightly + with slightly -)

Question 16

What is hydrogen bonding?

Answer 16

A special type of intermolecular attraction between hydrogen in a polar bond and an unshared electron pair on a nearby small electronegative atom (H with F, O or N, and these last three can be with another atom in their partially negative end)
- tronger atraction and needs considerable energy to break it

Question 17

Is hydrogen bonding a chemical bond?

Answer 17

No, it is a stronger form of dipole-dipole attraction

Question 18

Define London dispersion forces (Van der Waal forces)

Answer 18

Attraction between two nonpolar molecules due to temporary dipoles, the weakest of intermolecular forces, existing between all types of molecules

Question 19

What factors affect the strength of London dispersion forces?

Answer 19

The number of electrons in a molecule; more electrons result in stronger forces

Question 20

What is the effect of molecular size on dispersion forces?

Answer 20

As molecular size and molar mass increase, dispersion forces become stronger

Question 21

Fill in the blank: The boiling and melting points of compounds depend on the type and strength of the _______.

Answer 21

intermolecular forces present

Question 22

What are the types of intramolecular forces?

Answer 22

ionic, covalent and metallic bonds

Question 23

what charge does a cation has?

Answer 23

positive, its a metal

Question 24

what charge does a anion has?

Answer 24

negative, its a non-metal

Question 25

How to identify a ionic bond?

Answer 25

metal+non-metal, give electrons (this gives charge to the elements)

Question 26

What is the last level of a element called?

Answer 26

valance electrons

Question 27

elements in a table to identify elements:

Answer 27

name, Zymbol, z (atomic #), A (atomic mass), P (Protons), E (electrons) and N (neutrons)

Question 28

what charge does a proton, electron and neutron has?

Answer 28

positive, negative, neutral

Question 29

How to write the formula of a element?

Answer 29

fist metal then nonmetal

Question 30

formula of atomic mass:

Answer 30

P+N

Question 31

porcentages of the atomic mass in a atom:

Answer 31

99% in neucleous and 1% in E

Question 32

How to identify a Covalent bond?

Answer 32

non metal + non metal, share electrons equally

Question 33

steps on how to do a Louis dot driagram

Answer 33

1) sum of family of element x # of atoms of element, of each element (electrons present) 2) (8 x =/ atoms of H) + ( 2 x atoms of H) (electrons needed) 3) step 2 - step 1 (share electron) 4) step 3 divided by 2 (determine the # of bondings x---x) 5) step 3-1 (determine number of loose electrons)

Question 34

What element if present is always at the center of the atom?

Answer 34

C - Carbon

Question 35

whych type of covalent bond disolves? why?

Answer 35

polar covalent bond, because of its slight charge it pulls the slight or complete charge of other atoms e.g: water (polar because slightly + and -) disolves salt (full + and -) because the slightly positive (H) will "grab"/pull the negative of salt and the same with the slightly negative of water (O) will pull the positve of salt.

Question 36

How to identify if its non polar, polar or ionic

Answer 36

non polar: - of elements will give <0.5 polar: - of elements will give 0.5-1.7 ionic: - of elements will give >1.7

Question 37

what type of change does a metallic bond has?

Answer 37

Only physical change, because of this they keep their properties so they dont change names

Question 38

what are alloys?

Answer 38

combination of 2 metals

Question 39

list the intramolecular forces from strongest to weakest:

Answer 39

1) Metallic bonding 2) ionic bond 3)Polar Covalent Bond 4) Non Polar Covalent Bond

Question 40

Intermolecular forces are important because:

Answer 40

 Intermolecular forces of attraction operate over short distances. If not for these forces, the condensed phases (liquids and solids) would not exist; gases would never change to liquids and solids  Properties of liquids, such as boiling point, vapor pressure, viscosity, and heat of vaporization, depend on the strengths of the intermolecular forces of attraction.  Properties of solids, such as melting point and heat of fusion depend on the strengths of the intermolecular forces of attraction

Question 41

what happens if mass if greater when atoms are in proximity

Answer 41

the force between them will be greater

Question 42

What is a dipole-ion bond?

Answer 42

the atraction between a full + or - atom with a slightly + or - atom Its the atraction between ionic molecule and a covalent polar molecule

Question 43

why is dipole-ion stronger than dipole-dipole?

Answer 43

because it has a atom with hole charge

Question 44

What intermolecular force has a induced dipole-dipole?

Answer 44

Londond Dispersion, because some times one atom pulls more than the other one.

Question 45

How to know which force of a molecule has (steps):

Answer 45

1) if formula id given, draw lewis dot structure 2)if bonded directly with F, O or N its HYDROGEN BONG 3) if central atom doesnt have free electronsand the sorrounding elements are the same its non polar 4) if the molecule has just one element its non polar 5) If its non polar then its Van der Waals (London) 6) If non of the rules are aplied then its Dipole-Dipole

Question 46

what means a atom is hydrophobic?

Answer 46

that it doesnt disolve in water (ion-ion and dipole-dipole)

Question 47

what means a atom is hydrophilic?

Answer 47

that it disolves in water ( London)

Question 48

List the intermolecular forces from stronger to weaker

Answer 48

1) ion-ion 2) ion-dipole (1 and 2 are solids normally) 3) Hydrogen bond 4) dipole-dipole (3 and 4 normally are liquid or gas) 5) London dispersion (gas)