Ch5- Electrons and Bonding

Question 1

What is the expression used to calculate electrons in each shell?

Answer 1

2n²

Question 2

What are the 4 sub-shells?

Answer 2

s p d f

Question 3

How many electrons can an orbital contain?

Answer 3

2, with opposite spins.

Question 4

What is an atomic orbital?

Answer 4

A region around nucleus where it is likely to find an electron.

Question 5

What is the shape of the s-orbital?

Answer 5

Question 6

How many s, p d and f orbitals are there?

Answer 6

s = 1 (2 electrons)

p = 3 (6 electrons)

f = 5 (10 electrons)

d = 7 (14 electrons)

Question 7

What is the shape of the p orbitals?

Answer 7

Question 8

Describe the filling of orbitals and the overlap of 2 energy levels:

Answer 8

Question 9

There are 2 exceptions to the ‘aufbau’ principle. What are they and why do they behave this way?

Answer 9

Question 10

Explain how you would use ‘electron-in-box’ method?

Answer 10

Question 11

How does Shorthand Electron Configuration work and give an example using Potassium, K:

Answer 11

take the previous noble gas and put square brackets around it. Then add the rest of the orbitals if necessary.

E.g. Potassium, Atomic number 19:

Normal e.c. : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹

Shorthand: [Ar] 4s¹

E.g. Ar, Atomic number 18:

Shorthand = [Ne] 3s²3p⁶

Question 12

Which groups cover:

• the s-block
• the p-block
• the d-block

Answer 12

S-block= Groups 1-2

P-block= Groups 13-18

D-block= Groups 3-12

Question 13

Why do d-block (transition metals) form + ions and lose e- ?

Answer 13

D-block form + ions, they lose e- from 4s sub shell before 3d sub shell. This is because 4s sub shell fills before 3d sub shell, once 3d filled up, 3d sub shell falls to a lower energy level than 4s sub shell.

Question 14

In an ionic compound, describe the solubility:

Answer 14

Question 15

What is the definition of a covalent bond?

Answer 15

A covalent bond is the strong electrostatic attraction that form between the shared pair of electrons and the nuclei of the bonded atoms. A covalent bond form between non-metals. The attraction is ‘localised’ (unlike in ionic compounds, the attraction acts in all directions)

Question 16

What is a dative covalent bond?

Answer 16

Dative CB are formed when the shared pair of electrons has been provided by only one of the bonding atoms. The shared pair was originally a lone pair of electrons on one the bonded atoms.

Question 17

What is the octet rule?

Answer 17

The tendency of atoms to prefer to have eight electrons in the valence shell.

When atoms have fewer than eight electrons, they tend to react and form more stable compounds

Question 18

What are exceptions to the octet rule?

Answer 18

Some elements that form a CB will not have a noble gas electron structure, i.e. they do not end up with 8 electrons in their outer shell.

E.g. Boron Triflouride, BF3

Boron only has 6 electrons in outer shell (3 of its own) and Flourine obeys the octet rule by having 8 in its outer shell (7 of its own)

E.g. SF6, sulfur hexaflouride (a hypervalent molecule)

Octahedrral structure, Flourine obeys octet rule whereas Sulfur has 12 electrons in outer shell.