DN 2). Shapes Of Molecules Flashcards Preview

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Flashcards in DN 2). Shapes Of Molecules Deck (43):
1

A covalent bond is....

A shared pair of electrons

2

Two types of electron pairs

Bond pair
Lone pair

3

Order of repulsion

Lone pair-lone pair > bond pair - lone pair > bond pair - bond pair

4

Why do lone pairs repulse more than bond pairs

The lone pairs are clouds of negative charge
Will repel so are maximum distance apart
Bond pairs will do the same but the negative charge is spread out over a larger area
So their charge density is lower and so don't repel as much

5

Ionic melting point

High
Lattice
Lots of strong electrostatic attraction between opp charged ions

6

Ionic conductive

Pint when solid
Only molten or in solution
Ions need to be free to move to carry the current

7

Strength of ionic

Strong but brittle
Lattice
Electrostatic attraction between opp charged ions
Brittle because if distorted like charges adjacent so repulsion breaks apart

8

All molecules contain which type of bonding

Covalent

9

Ionic solubiltiy

Soluble.
Polar water molecules attracted to ions
surround them and make lattice break

10

Simple molecular mp

Low.
Strong covalent bonds between atoms
Weak IMF between molecules

11

Simple molecular conductivity

No.
No charged particles to move to carry the current.

12

Simple molecular strength

Not strong
Strong covalent bonds between atoms
Weak IMF between molecules

13

Simple molecular solubility

Not in water.
No charged particles to attract the polar water molecules

14

Giant covalent mp

High
Macromolecular structure
lots of string covalent bonds
lots of energy

15

Giant covalent electrical conductivity

No
no charged particles to move to carry the current

16

Giant covalent strength

strong
macromolecular structure
lots of strong covalent bonds
lots of energy to break

17

Giant covalent solubility

No
no charged particles to attract polar water molecules

18

Metallic mp

High
lattice of positive ions surrounded by a sea of delocalised electrons
strong electrostatic attraction between oppositely charged particles

19

metallic conductivity

yes even when solid
electrons are free to move to carry the current

20

Metallic strength

Strong
lattice of positive ions surrounded by a sea of delocalised electrons
strong electrostatic attraction between oppositely charged particle

21

Metallic solubility

Insoluble
Doesn't attract polar water molecules to disrupt the lattice

22

what is ionic bonding

electrostatic attraction between oppositely charged ions

23

what is a covalent bond

a shared pair of electrons

24

what is metallic bonding

electrostatic attraction between positive ions and negative electrons

25

what is a dative (or coordinate) bond and how do you draw it

a shared pair of electrons when both electrons come from the same atom
draw it with an arrow

26

is there any difference between a dative bond and a normal covalent bond

no

27

electronegativity definition

the power of an atom to attract the electron density in a covalent bond towards itself

28

nuclear charge....... electronegativity

more protons, stronger attraction between nucleus and bonding pair of electrons

29

atomic radius........ electronegativity

closer to the nucleus, stronger attraction between nucleus and bonding pair of electrons

30

shielding....... electronegativity

less shells of electrons between the nucleus and the electrons, less shielding (less repulsion), stronger attraction between nucleus and bonding pair of electrons

31

as you go across a period electronegativity........
Why?

increases
+nuclear charge
distance of bonding electrons from the nucleus = same
shielding = same
therefore bonding electrons attracted more strongly

32

as you go down a group electronegativity..........
why?

decreases
despite + nuclear charge
distance of bonding electrons from nucleus increases
shielding increases
therefore bonding electrons attached less strongly

33

3 types of IMF (weakest to strongest)

van der waals...........permanent dipole-permanent dipole...........hydrogen bonding

34

explain van der waals forces

temporary dipole - induced dipole attraction
at any instance electron distribution is unsymmetrical due to the movement of electrons
this creates a temporary dipole
the electrons around this dipole will move causing an induced dipole.

35

stronger van der waals......

larger molecule
more electrons
STRONGER van der waals
(NB shape is important to do with packing)

36

explain permanent dipole - permanent dipole forces

polar molecule
the permanent dipoles attract each other
(NB watch for symmetry resulting in there not actually being a dipole)

37

explain hydrogen bonds

the strongest dipole 0 dipole force which exists between the lone pair of electrons o a NOF atom and a H atom that is d+ because it is attached to a NOF

38

sulfate ion

SO4 2 minus

39

hydroxide ion

OH MINUS

40

nitrate ion

NO3 2MINUS

41

carbonate ion

CO3 2 MINUS

42

ammonium

NH4 PLUS

43

ammonia

NH3