2.2 Electrons, Bonding And Structure

Question 1

Configuration of electrons for the first four shells

Answer 1

2, 8, 18, 32

Question 2

What is an atomic orbital?

Answer 2

A region around the nucleus that can hold up to 2 electrons, with opposite spins.

Question 3

What shape is an s orbital

Answer 3

Sphere

Question 4

Which shells contain s orbitals

Answer 4

All 4 shells contain one s orbital

Question 5

What shape is a p-orbital

Answer 5

Dumb-bell

Question 6

What are the three p-orbitals

Answer 6

Px
Py
Pz

Question 7

Which shells contain p-orbitals

Answer 7

2nd, 3rd and 4th subshells contain 3 p-orbitals

Question 8

Which shells contain d-orbitals

Answer 8

3rd and 4th subshells contain 5 d-orbitals

Question 9

How do sub-shells fill according to energy levels

Answer 9

In each shell, new type of sub-shell has higher energy
Highest energy level in 3rd shell overlaps with lowest energy level in 4th shell

So
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d

Question 10

Why do electron pairs in a cloud have opposite spins

Answer 10

They’re negatively charged and repel each other
Opposite spins helps to counteract repulsion

Question 11

Why do orbitals with the same energy occupy singly first

Answer 11

Prevents repulsion between paired electrons

Question 12

Ionic bonding definition

Answer 12

Electrostatic attraction between positive and negative ions

Question 13

How are giant ionic lattices formed

Answer 13

Oppositely charged ions attract each other in all directions equally

Question 14

Example of a giant ionic lattice

Answer 14

NaCl

Question 15

Ionic compounds melting and boiling points

Answer 15

High temperatures needed to provide energy needed to overcome strong electrostatic attraction between ions.
Therefore , high melting and boiling points

Question 16

Solubility in ionic compounds

Answer 16

Many dissolve in polar solvents (water), water molecules break down the lattice and surround each ion in solution
However, with compounds made of ions with large charges, ionic attraction may be too strong for water to be able to break down the lattice structure, then would not be soluble.

Question 17

Electrical conductivity in ionic compounds

Answer 17

Don’t conduct electricity in a solid state as ions are in a fixed position in giant ionic lattice and no mobile charge carriers.
Once molten/ aqueous ionic compounds conduct electricity as solid ionic lattice breaks down and ions are free to move as mobile charge carriers

Question 18

Definition of covalent bonding

Answer 18

Strong electrostatic attraction between shared pair of electrons and the nuclei of the bonded atoms.

Question 19

How many covalent bonds does carbon form

Answer 19

4

Question 20

How many covalent bonds does nitrogen form

Answer 20

3

Question 21

How many covalent bonds does oxygen form

Answer 21

2

Question 22

How many does covalent bonds does hydrogen form

Answer 22

1

Question 23

Configuration of BF3

Answer 23

3 covalent bonds, only 6 electrons on outer shell of boron

Question 24

What is a dative covalent/ coordinate bond

Answer 24

Shared pair of electrons has been supplied by one of the bonding atoms only

Question 25

Example of dative covalent bonding

Answer 25

NH4+

Question 26

What is average bond enthalpy

Answer 26

Measurement of covalent bond strength

Question 27

Shape name for 4 bonded pairs

Answer 27

Tetrahedral

Question 28

Bond angles for tetrahedral shape

Answer 28

109.5

Question 29

Shape for 3 bonded pairs and 1 lone pair

Answer 29

Pyramidal

Question 30

Pyramidal shape bond angles

Answer 30

107

Question 31

Shape for 2 bonded pairs and 2 lone pairs

Answer 31

Non-linear

Question 32

Angles in non-linear shape

Answer 32

104.5

Question 33

Shape for 2 bonded pairs

Answer 33

Linear

Question 34

Angles in linear shape

Answer 34

180

Question 35

Shape for 3 bonded pairs

Answer 35

Trigonal planar

Question 36

Angles in trigonal planar shape

Answer 36

120

Question 37

Shape for 6 bonded pairs

Answer 37

Otahedral

Question 38

Angles in octahedral shape

Answer 38

90

Question 39

How are the different repulsions by different electron pairs ordered

Answer 39

2 bonded < one bonded one lone < 2 lone

Question 40

Why does the presence of lone pairs decrease the angle

Answer 40

Lone pairs repel more strongly than bonded, so lone pairs repel bonded pairs slightly closer together which decreases the bond angle

Question 41

Definition of electronegativity

Answer 41

The ability of an atom to attract the bonding electrons in a covalent bond

Question 42

Covalent polar bonds in terms of electronegativity

Answer 42

The bonded electron pair is shared unequally between bonded atoms due to different electronegativity values. Creates a permanent dipole.

Question 43

Polar molecules in terms of electronegativity

Answer 43

For molecules with more than one polar bonds there will be multiple dipoles and depending on the shape they either will or wont cancel eachother out. If the dipoles don’t cancel out, it is a polar molecule.

Question 44

What are London forces

Answer 44

Weak intermolecular forces that exist between all molecules

Question 45

How are London forces formed

Answer 45

Movement of electrons produces changing dipoles in a molecule and an instantaneous dipole exists which induces a dipole on a neighbouring molecule this induction continues

Question 46

How does the strength of London forces change

Answer 46

In a molecule with more electrons, there’s larger instantaneous and induced dipoles, greater induced interactions and stronger attractive forces

Question 47

What are permanent dipole-dipole interactions

Answer 47

Forces that act between the permanent dipoles in different polar molecules Stronger than London forces

Question 48

What happens in a simple molecular lattice

Answer 48

Molecules held in place by weak intermolecular forces Atoms within each molecule bonded strongly by covalent bonds

Question 49

Melting and boiling points of simple molecular substances

Answer 49

In a lattice, weak IMF broken easily, low melting and boiling points

Question 50

Solubility of non-polar molecular substances

Answer 50

IMF form between non-polar solvent, these interactions weaken and break IMF in simple molecular lattice, compound dissolves. Little interactions with polar solvents, IMF within polar solvent too strong to break, compound doesn’t dissolve

Question 51

Solubility of polar simple molecular substances

Answer 51

Polar solute and solvent molecules can attract each other, solubility depends on strength of dipole

Question 52

Electrical conductivity in simple molecular structures

Answer 52

No mobile charged particles, nothing to complete electrical circuit, non-conductors

Question 53

Where can hydrogen bonds form

Answer 53

Between molecules containing an electronegative atom with a lone pair (oxygen nitrogen fluorine) And an hydrogen atom attached to the electronegative atom (H-O H-N H-F)

Question 54

Why is ice less dense than water

Answer 54

Hydrogen bonds hold water molecules in open lattice structure, water molecules further apart in ice than water

Question 55

Melting and boiling points of water

Answer 55

Relatively high due to hydrogen bonds More energy is needed to break the H bonds, as it has those as well as London forces