bonding

Question 1

outline the structure of a metal

Answer 1

Metals are a net of cations surrounded by a sea of delocalised electrons.

Question 2

referring to the structure of a metal, why are they malleable and ductile and conductive

Answer 2

Valence electrons breaks away from the atoms, leaving behind positive ions and move randomly through the lattice, allowing for electrical conduction.
Electrons act as a glue so that metals are malleable and ductile.

Question 3

boiling point of metal generally is?

Answer 3

high

Question 4

melting point of metal generally is?

Answer 4

high

Question 5

why do metals maintain their lattice structure

Answer 5

strong electrostatic forces between cations and delocalised electrons

Question 6

define covalent bonding

Answer 6

when two or more elements bond via the sharing of electrons usually non-metals

Question 7

define ionic bonding

Answer 7

Electrons are transferred from one atom to another forming positive and negative ions, held together by electrostatic attraction. (metals and non-metals)

Question 8

define electronegativity and its uses

Answer 8

Electronegativity is the ability of an atom to attract shared electrons. Can be useful in determining if a bond is nonpolar covalent, polar covalent or ionic.

Question 9

what is the difference in electronegativity for non polar bonds?

Answer 9

they will have the same electronegativity

Question 10

do polar covalent bonds differ in electronegativity

Answer 10

yes around <2 absolute value difference in electronegativity

Question 11

list the types of compounds

Answer 11

metallic lattices, ionic compounds, covalent molecular and covalent network/lattice

Question 12

list the features of ionic lattice compounds

Answer 12

o Giant ionic lattices containing oppositely charged ions
o Always compounds
o Hard and brittle
o Slide so that opposite charges repel, which is why these are brittle
o When solid they do not conduct electricity, ionic solutions do though

Question 13

list the features of covalent molecular substances

Answer 13

• strong intramolecular bonds but weak intermolecular bonds, therefore they have low melting and boiling points
• soft
• non conductive

Question 14

list the features of covalent lattice substances

Answer 14

o Covalent bonding extends indefinitely throughout the whole crystal
- extremely strong
o Also known as covalent network
o Examples are diamond

Question 15

describe how an ionic substance is written as a lewis dot diagram

Answer 15

the metal always comes first, simply as a

coefficient:metal:positive charge
then add the nonmetal = coefficient:non-metal with lewis dot diagram: charge: square brackets

Question 16

when is a molecule non-polar

Answer 16

• each bond is non polar and there are no unbonded electron pairs
• no net dipole moment (all moments cancel out)
• each bond has the same polarity

Question 17

Molecule is polar if:

Answer 17

• there is a net dipole moment
• each bond is non-polar but there are unbonded electron pairs
• bonds in the molecule have different polarities or there are unbonded electron pairs

Question 18

list all types of shapes for molecules

Answer 18

linear, pyramidal, bent, trigonal planar, tetrahedral

Question 19

describe linear shape and differentiate between polar and non polar

Answer 19

• non-polar means that the two atoms attached to the central atom are the same and there are no lone pairs on the central molecule
• Polar means that the two atoms attached to the central atom are different, and thus have a net dipole moment.

Question 20

can a compound with only 2 elements be anything but linear

Answer 20

no but it can be polar e.g HCl

Question 21

describe bent shape and differentiate between polar and non polar

Answer 21

a bent molecule is a linear molecule that has a pair of unbonded electrons in the central atom, is always olar

Question 22

describe pyramidal shape and differentiate between polar and non polar

Answer 22

trigonal planar shape but unbonded electron pair, eg NH3 and is always polar

Question 23

describe trigonal planar shape and differentiate between polar and non polar

Answer 23

always symmetrical, no unbonded electron pairs but can have a net dipole movement if one of the connected atoms are differen

Question 24

describe tetrahedral shape and differentiate between polar and non polar

Answer 24

always symmetrical, can have net dipole movement, no unbonded electron pairs

Question 25

the larger the difference in electronegativity?

Answer 25

the more polar the bond, the more attractive the substance is to electrons, the less reactive it is

Question 26

describe the 3 main intermolecular forces

Answer 26

dispersion dipole dipole hydrogen bonding

Question 27

list the 3 intermolecular forces from strongest to weakest

Answer 27

hydrogen bonding > dipole dipole > dispersion

Question 28

what are dispersion forces and how do they work

Answer 28

Dispersion forces are attractions between negatively charged electron cloud of one molecule and the positive charged nuclei of neighboring molecules. How do they work: since electrons move they are unevenly distributed on an atom or molecule. This creates a temporary dipole movement, aka more electrons on one side as the electron cloud is distorted, and this creates attraction between atoms and molecules. TEMPORARY

Question 29

simple definition of dispersion force

Answer 29

(it catches the window of the net dipole and induces another molecule to become a dipole, creating an electro static attraction.) TEMPORARY

Question 30

factors which influence dispersion force

Answer 30

- No. of electrons (more electrons more dispersion force) - Size of the atom or the molecular weight (more atoms, more electrons) - Shape of the molecule (more compact, less dispersion force)

Question 31

describe dipole dipole attraction

Answer 31

2. Dipole-dipole attraction or dipole forces are the electrostatic attraction between two polar molecules. The attraction between the partial positive on one molecule and the partial negative on the other.

Question 32

describe hydrogen bonding

Answer 32

3. Hydrogen bonding are a special case of dipole forces. This occurs between molecules in which hydrogen is bonded to nitrogen, oxygen or fluorine.

Question 33

do all substances display dispersion forces?

Answer 33

yes, becasue the electron clouds of molecules can be distorted