C5 - Electrons and Bonding

Question 1

What are orbitals?

Answer 1

Regions around the nucleus of an atom where electrons are more likely to be found at any one time.
All orbitals can hold only two electrons only.

Question 2

What orbitals are found in the first shell?

Answer 2

s orbitals

Hold 2 e-

Question 3

What orbitals are found in the second shell?

Answer 3

s and p orbitals

p holds 6 e-

Question 4

What orbitals are found in the third shell?

Answer 4

s, p and d orbitals

d holds 10 e-

Question 5

What orbitals are found in the fourth shell?

Answer 5

s, p, d and f orbitals.

f holds 14 e-

Question 6

Where are electrons found?

Answer 6

They exist at fixed energy levels.
Energy levels are called principle energy levels and are given a principle quantum number (n)

They’re found at orbitals.

Question 7

What are s orbitals like?

Answer 7

Spheres
1s is the closest to the nucleus

Altogether it holds 2 electrons per orbital

The 4s orbital has less energy than the 3d orbital

(When removing electrons to make ions, electrons are first taken from the 4s orbital (whereas they’d be added to 3d first))

Question 8

What are p orbitals like?

Answer 8

A figure of eight in 3 directions (x y z)

Each p orbital holds 6 electrons
2x 2y 2z

Question 9

Hat are d orbitals like?

Answer 9

They come in 5 shapes

(2 electrons at end of each type of shape)
They hold 10 electrons altogether

The 3d orbital has more energy than the 4s orbital

(When removing electrons to make ions, electrons are first taken from the 4s orbital (whereas they’d be added to 3d first))

Question 10

What are f orbitals like?

Answer 10

They come in 7 shapes

2 electrons at end of each type of shape
They hold 14 electrons altogether

Question 11

What is Hund’s rule?

Answer 11

Hund’s rule states that single electrons occupy all empty orbitals within a sub-level before they start to form pairs in orbitals.
(This rule is broken with chromium and copper)

Question 12

Why do ionic compounds have high melting and boiling points?

Answer 12

Because there are very strong ionic bonds and strong electrostatic forces which require a lot of energy to break.

It is a lattice structure with bonds in all directions so there are many ionic bonds.

Question 13

What are melting and boiling points affected by?

Answer 13

Charge - strengths of attraction

Size of the ions - a smaller ion means the electrons are closer to the nucleus so there are stronger forces and more energy therefore more energy is needed to overcome these bonds

Question 14

What’s electron spin?

Answer 14

A property of electrons represented by arrows in a box.
Two electrons in an orbital must have opposite spins which help to counteract the repulsion between the negative charged of the two electrons.

Question 15

What’s the order which orbitals are filled?

Answer 15

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

5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, (8s, 5g, 6f, 7d, 8p, and 9s)

Question 16

What’s ionic bonding?

Answer 16

The electrostatic attraction between oppositely charged (positive and negative) ions.
It holds together cations (positive) and anions (negative) in ionic compounds.
This produces a giant ionic lattice

Question 17

What is the solubility of ionic compounds?

Answer 17

Many ionic compounds dissolve in polar solvents e.g. water.
The slight charges of the polar water molecules break down the lattice and surround each ion in solution.

In a compound made of ions with large charges, the ionic attraction may be too strong or water to break down the lattice structure. This type of compound wouldn’t be very soluble.

Question 18

What affects the solubility of ionic compounds?

Answer 18

The relative strengths of the electrostatic attraction within the ionic lattice and between the ions and water molecules.
(As charge increases, solubility decreases)

Question 19

What is the conductivity of ionic compounds?

Answer 19

Ionic lattices cannot conduct electricity when solid as the ions aren’t free to move.
When molten or dissolved however, the ions are free to move carrying charge so conduction can occur.

Question 20

What are lone pairs?

Answer 20

Pairs of electrons which aren’t shared with another atom.

Question 21

What is covalent bonding?

Answer 21

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

(The overlap of atomic orbitals occuring between non-metallic elements)

It is very different to ionic bonding as it is very localised, acting solely between the shared pair of electrons and the nuclei of the bonded atoms, producing a molecule.

Question 22

What is the expansion of the octet?

Answer 22

The fact that atoms can result in having more (or less) than 8 electrons in its outer shell.
A case where an atom shares more than eight electrons with its bonding partners.

The octet rule can be ‘expanded’ by some elements by utilizing the d-orbitals found in the third principal energy level and beyond. Sulfur, phosphorus, silicon, and chlorine are common examples of elements that form an expanded octet.
E.g. SF6

Question 23

What’s another name for dative covalent bonding?

Answer 23

Coordinate bonding

Question 24

What is dative covalent bonding?

Answer 24

A co-ordinate bond (also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom. (rather than one from each).

A lone pair is needed for dative covalent bonding - the lone pair on the atom donates its electrons into the vacant orbital on the hydrogen.

Question 25

What is average bond enthalpy?

Answer 25

Bond energy.

The larger the bond enthalpy, the stronger bond.

Question 26

What is the max number of electrons in the first four shells?

Answer 26

Shell 1: 2
Shell 2: 8
Shell 3: 18
Shell 4: 32

As of shell 3, compounds are able to use the ‘expansion of the octect’ rule.

Question 27

What is the electron configuration of sodium (full and short hand)
Na 11

Answer 27

Full:
1s2 2s2 sp6 3s1

Short:
[Ne] 3s1

Question 28

What is the electron configuration of fluorine:

F9

Answer 28

1s2 2s2 2p5

Question 29

What is the electron configuration of krypton:

Z = 36

Answer 29

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Question 30

What does each symbol mean in 1s2?

Answer 30

1 is the shell
s is the sub shell
2 is the number of electrons

Question 31

What are double and triple covalent bonds?

Answer 31

The electrostatic attraction between two or three shared pairs of electrons and the nuclei of the bonding atoms.