Electrons and bonding

Question 1

How many orbitals are in each subshell?

Answer 1

s - 1 orbital
p - 3 orbitals
d - 5 orbitals
f - 7 orbitals

Question 2

How many electrons are there in each shell?

Answer 2

1st shell - 2 electrons (s)
2nd shell - 8 electrons (s, p)
3rd shell - 18 electrons (s, p, d)
4th shell - 32 electrons (s, p, d, f)

Question 3

What are the 3 rules of orbital filling?

Answer 3

• Orbitals fill in order of increasing energy.
• Each orbital can hold a maximum of two electrons and they must have opposite spins.
• Orbitals with the same energy mus be singularly occupied before they can be paired.

Question 4

Why must electrons in an orbital have opposite spins?

Answer 4

To counteract the repulsion between the two negatively charged electrons.

Question 5

What shape is the s orbital?

Answer 5

spherical/sphere

Question 6

What shape is the p orbital?

Answer 6

dumbbell shaped

Question 7

What are the similarities and differences between the p orbitals?

Answer 7

Similarities: both lobes are the same size and shape, all 3 p orbitals are of equal energy.
Differences: the orientation/direction of each of the 3 p orbitals are different as they are all at right angles to eachother.

Question 8

What are the similarities and differences between the d orbitals?

Answer 8

Similarities: they’re all of equal energy.
Differences: they’re all uniquely shaped.

Question 9

What’s the % chance of finding an electron in an orbital?

Answer 9

95%

Question 10

In orbital filling diagrams, why is 4s filled before 3d?

Answer 10

Because the energy of the 4s subshell is actually slightly lower than 3d.

Question 11

Why do we still put 3d before 4s when writing electron configurations?

Answer 11

When writing configurations, we stick to grouping shells.

Question 12

Why are Se2- and Se+ ions both possible?

Answer 12

Se2- gains 2 electrons so 4p subshell is full so stable. Se+ loses 1 electron so 4p subshell is half full so stable (as all orbitals are singularly occupied).

Question 13

How do we write shorthand notation?

Answer 13

[previous noble gas]remaining subshells

Question 14

How would we write Kr in shorthand?

Answer 14

[Ar]3d10 4s2 4p6 as it’s ALWAYS the previous noble gas.

Question 15

What are ionic bonds?

Answer 15

The electrostatic forces of attraction between oppositely charged ions that act in ALL directions and between ALL ions in a structure.

Question 16

What is a lattice?

Answer 16

A regular repeating structure.

Question 17

What are the disadvantages of the ball and stick model?

Answer 17

• Doesn’t show the positiive and negative ions.
• Ions may not all be the same shape and size.
• Doesn’t show the electrostatic forces of attraction acting in all directions.

Question 18

What are the properties of ionic compounds?

Answer 18

• Regular lattice structure.
• High melting points.
• Doesn’t conduct electricity when solid.
• Dissolves in polar solvents.

Question 19

Why do ionic compounds have high melting points?

Answer 19

Lots of energy is required to overcome the strong electrostatic forces of attraction between ions. Also, the higher the charge, the higher the required temperature.

Question 20

Why don’t ionic compounds conduct electricity when solid?

Answer 20

The ions are in fixed positions so cannot move to carry charge and there are no other mobile charge carriers.

Question 21

Why do ionic compounds dissolve in polar solvents?

Answer 21

The solvent molecules attract and surround the ions which breaks down the lattice.

Question 22

What are the similarities and differences between ionic and covalent bonding?

Answer 22

Similarities: both involve electrostatic attraction, both give stability to their ions/molecules.
Differences: ionic bonding involves attraction between oppositely charged ions whereas covalent bonding involves attraction between shared electrons and nuclei, ions form lattices whereas covalent forms molecules, covalent involves sharing electrons whereas ionic involves transferring electrons.

Question 23

What are covalent bonds?

Answer 23

The overlap of atomic orbitals each containing 1 electron to give a shared pair of negatively charged electrons which are attracted to the positively charged nuclei.

Question 24

What are the characteristics of covalent bonds?

Answer 24

They’re localised and directional.

Question 25

What is a molecule?

Answer 25

The smallest part of a covalent compound that can exist while retaining the chemical properties of the compound.

Question 26

Which 3 elements are stable with 6 electrons?

Answer 26

Beryllium, Boron and Aluminium

Question 27

What is the “expanding the octet” rule?

Answer 27

Only applicable between groups 5-7 and from period 3 downwards. These elements can be stable with up to 12 electrons as the d subshell becomes available for the expansion.

Question 28

What is a dative covalent bond? (aka coordinate bond)

Answer 28

Both electrons in the shared pair of electrons have been supplied by 1 atom only in a covalent bond.

Question 29

What are lone pairs?

Answer 29

Pairs of electrons which are not involved in the covalent bond.

Question 30

What is average bond enthalpy?

Answer 30

A measurement of covalent bond strength.

Question 31

The larger the bond enthalpy…

Answer 31

the stronger the covalent bond as it requires more energy to overcome the bond.