Chapter 5 Electrons And Bonding

Question 1

What is the definition of electron configuration?

Answer 1

A shorthand representation that shows how electrons occupy sub-shells in an atom

Question 2

What is an orbital?

Answer 2

A region of space in an atom around a nucleus that can hold up to 2 electrons with opposite spin

Question 3

What is a sub-shell?

Answer 3

A group of orbitals of same type within a shell

Question 4

What is a shell?

Answer 4

A group of atomic orbitals with the same principal quantum number,n, also known as the main energy level

Question 5

What are the different sub shells?

Answer 5

The S- sub shell in the first shell; the S and P- sub shell in the second shell; the S,P and D-sub shell in the third shell and the S,P,D and F-sub shell in the fourth shell.

Question 6

What the 3D shape of an s-orbital?

Answer 6

Spherical

Question 7

What is the 3D shape of a P-orbital?

Answer 7

Dumbbell

Question 8

What are the different orbitals in a P-sub shell?

Answer 8

In a P-orbital there are three different orbitals (x,y,z)
Z orbital- dumbbell vertical, X-orbital- dumbbell horizontal and Y orbitals- dumbbell diagonal

Question 9

How many orbitals make up the D-sub shell and how many electrons can it hold?

Answer 9

There are 5 orbitals that make up a d-orbital therefore it can hold up to 10 electrons

Question 10

How many orbitals make up the F-sub shell and how many electrons can it hold?

Answer 10

There are 7 f-orbitals that make up the f-sub shell therefore it can hold up to 14 electrons.

Question 11

State how many electrons there can be in the first, second, third and fourth shell?

Answer 11

First- 2 electrons, Second- 8 electrons, Third- 18 electrons and Fourth- 32 electrons

Question 12

What is the correct order of sub shells?

Answer 12

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 4f….

Question 13

What are the exceptions to Chromium and Copper?

Answer 13

In order to achieve a stable arrangement of lower energy, one of the 4s electrons is promoted into the 3d sub shell. Therefore, creating a lower repulsion.

Question 14

How can shorthand electron configurations be written?

Answer 14

Electron configurations can be expressed more simply by using the previous noble gas in the periodic table and then adding on the outer electron shells.

Question 15

Where are the s,p,d and f blocks found on the periodic table?

Answer 15

S-block: Left block consisting of two groups
P-block: Right block consisting of six groups
D-block: Centre block consisting of ten groups
F-block: Found at the bottom of the periodic table

Question 16

What is the electron configuration of ions in the s or p-block?

Answer 16

When forming these ions, the highest energy level loses or gains electrons

Question 17

How is the electron configuration of ions from d-block elements made?

Answer 17

Because the 4s sub shell is at a lower energy (electrons always fill from the lower energy levels first) than the 3d sub shell, this means that the 4s sub shell fills before the 3d sub shell consequently this means that the 4s sub shell also empties before the 3d sub shell.

Question 18

What is the definition of ionic bonding?

Answer 18

The electrostatic attraction between oppositely charged ions

Question 19

What is the structure of ionic compounds?

Answer 19

When oppositely charged ions attract, they do so in all directions. This leads to the formation of a giant ionic lattice.

Question 20

What are the properties of ionic compounds?

Answer 20

Melting and boiling point- takes a large amount of energy to overcome all the strong electrostatic forces of attraction between oppositely charged ions that acts in all directions within a giant ionic lattice. Therefore, Ionic compounds have high melting and boiling points.
Solubility- Many ionic compounds dissolve in polar solvents like water. In a water molecule, the oxygen atom is slightly negative and the hydrogen atom is slightly positive. When an ionic compound is placed in water, oxygen atoms of the water molecule attract to the positive ions of the compound, while the hydrogen atom attracts to the negative ion of the compound. If these attractive forces are stronger than the attractive forces between the ions, the compounds dissolve.
Electrical conductivity- In a solid state, ionic compounds dont conduct electricity because the ions are fixed in a giant ionic lattice by strong electrostatic forces of attraction and therefore can’t move . However, when molten or in aqueous states, ionic compounds are able to conduct electricity because ions are able to move.

Question 21

What makes an ionic bond strong?

Answer 21

The strength of an ionic bond increases as the size of the ion decreases or the charge of the ion increases.

Question 22

What is the definition of covalent bonding?

Answer 22

A strong bond between two atoms due to the electrostatic attraction between a shared pair of electrons and the atomic nuclei.
Or
A shared pair of electrons

Question 23

What is dative covalent bonding?

Answer 23

A shared pair of electrons which has been provided by one of the atoms only (the donor)

Question 24

What is the process of dative covalent bonding?

Answer 24

The electrons of the shared pair are provided by one species (donor) and it shares the electrons with the acceptor. Donor species will have lone pairs in their outer shells, while acceptor species will be short of their ‘octet’ or maximum.

Question 25

What is the dative covalent bond of ammonia?

Answer 25

—— —— +
| H |
| | |
| H— N —>H |
| | |
| H |
——— ——-

Question 26

Explain SF6

Answer 26

Sulfure hexafluoride is able to expand the octet rule and contain 12 electrons in the outer shell as it has available orbitals to accommodate more electrons.

Question 27

Explain Bf3

Answer 27

Boron trifluoride can contain less than the maximum octet as it is stable due to the central atom maximising the number of possible covalent bond pairs.

Question 28

How are simple molecules structured?

Answer 28

Simple molecules contain only a few atoms held together by covalent bonds, however each molecule is attracted to other neighbouring molecules by weak intermolecular forces which hold them together.

Question 29

What are the properties of simple molecules?

Answer 29

Low Boiling Point- Intermolecular forces are easily overcome and broken
Don’t conduct electricity- There are no mobile charge carriers (ions and electrons)

Question 30

How is Diamond structured?

Answer 30

In a giant covalent structure/lattice as each carbon atom forms 4 bonds with 4 other carbon atoms, forming a giant network.

Question 31

What are the properties of Diamond?

Answer 31

Very high melting point- Network of strong covalent bonds which take a lot of energy to be broken.
Doesn’t conduct electricity- no free mobile charge carriers

Question 32

What other giant covalent structure has the same properties as Diamond?

Answer 32

Silicon trioxide (sand)

Question 33

How is Graphite structured?

Answer 33

This is an allotrope of carbon as each carbon atom forms 3 bonds with 3 other carbon atoms leaving a delocalised electron for each carbon atom which is free to move between the layers. There is an attraction between the layers of carbon atoms and the delocalised electrons.

Question 34

What are the properties of Graphite?

Answer 34

Soft and slippery- the layers of the carbon atoms can slide over each other
High melting point- a large amount of energy is required to overcome the covalent bonds
Conducts electricity- delocalised electrons that can move throughout the structure

Question 35

What is the average bond enthalpy?

Answer 35

Serves as a measurement of covalent bond strength. The larger the value of the average bond, the stronger the covalent bond.

Question 36

What are the properties of monatomic substances?

Answer 36

Low melting and boiling points because there are weak forces in between the atoms which means that little energy is required to break the bonds.
Insoluble
Does not conduct electricity because there are no free mobile charge carriers

Question 37

Explain why giant covalent substances have high melting and boiling points

Answer 37

Giant covalent structures have high melting and boiling points due to the strong network of covalent bonds which requires a lot of energy to overcome.

Question 38

Explain why it would be incorrect to describe Na2O as a “molecule”?

Answer 38

Because the substance is a compound made up of positively and negatively charged ions

Question 39

Why are covalently bonded substances insoluble?

Answer 39

They have a non polar structure and therefore can only dissolve in non polar solvents

Question 40

Describe and explain the electrical conductivity of sodium in its solid and molten states

Answer 40

Sodium conducts electricity in solid and molten states as it contains delocalised electrons in both states,

Question 41

Describe what is meant by the terms ionic lattice, in terms of arrangement and particles present?

Answer 41

Regular repeating arrangement of oppositely charged ions that acts in all directions due to the electrostatic attraction.