5 - Electrons and bonding

Question 1

What is the principle quantum number.

Answer 1

The shell number or energy level number. (n)

Question 2

In shell number n, how many electrons are there.

Answer 2

2n^2

Question 3

Describe an s orbital.

Answer 3

Spherical area around nucleus, holds two electrons. Greater the shell number, greater the radius of s orbital.

Question 4

Describe a p orbital.

Answer 4

Dumbell shape, holds two electrons. There are three p orbitals for each dimension.

Question 5

How many orbitals do d and f orbitals have?

Answer 5

d = 5 f =7

Question 6

Where is there an unexpected overlap in the energy of sub shells of an atom?

Answer 6

The 4s sub shell has less energy than the 3D despite being in a higher energy level. This means that the 4s sub shell fills fist. After being filled, the 4 s orbital has higher energy than 3D so it also empties first.

Question 7

Why just electrons have opposite spin in a sub shell?

Answer 7

The opposite soon helps to counter act the negative charges repelling each other.

Question 8

What is the electronic configuration of krypton from the nearest Nobel gas. Atomic number = 36

Answer 8

[Ar] 4s2, 3d10, 4p6.

Question 9

On the periodic table, where are the highest energy level electrons found in the s, p and d blocks?

Answer 9

Highest energy electrons in:
S block = left hand side.
P block = far right hand side.
D block = centre.

Question 10

What is the electron configuration of cobalt

Answer 10

[Ar] 3d5 4s1

Despite the 4 s energy level having less energy than 3D (so it should fill up first) it is more stable to have a half filled d block

Question 11

Describe the order in which electrons fill orbitals.

Answer 11

Orbitals are filled in order of increasing energy. Because the 4s subshell has a lower energy level than the 3d subshell, it fills first. Electrons in the same orbitals have opposite spins. Orbitals with the same level are occupied singly before doubly.

Question 12

Why do electrons have opposite spins in the same orbital?

Answer 12

The opposite spin helps to cancel out the negative charge.

Question 13

Give the order in which you would fill up sub shells.

Answer 13

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

Question 14

When an ion forms, which sub shell fills and empties first, 4s or 3d.

Answer 14

As the 4s orbital has less energy than the 3d orbital, it fills first. However, once they are both filled, 3d has less energy than the 4s orbital so the 4s orbital is also emptied first.

Question 15

Definition of ionic bonding.

Answer 15

The electrostatic attraction between positive and negative ions. It holds cations and anions together.

Question 16

How are dot and cross diagrams drawn for bonded ions?

Answer 16

Both reactants are drawn and a curved arrow is used to represent electron transfer. The products are not joined, instead each ion is in square brackets with the charge on the outside.

Question 17

What kind of structure do ions form?

Answer 17

As ions attract opposite charge in all directions, a giant ionic lattice is formed. Each ion has 6 oppositely charged ions surrounding it.

Question 18

How does the melting point differ in different ionic lattices.

Answer 18

Melting points are higher for lattices containing ions with a higher charge. Greater charge = greater ionic attraction. The size of the ion also effects the ionic attraction.

Question 19

Are ionic compounds soluable?

Answer 19

Ionic compounds dissolve in polar solvents. Polar water molecules break down the ioic lattice and surround each ion in the solution.

Question 20

What makes an ionic compound soluable?

Answer 20

Greater ionic attraction makes an ionic lattiice less soluable. The greater the charge, the greater the ionic strength. The water cannot break it down.

Question 21

Give two ways of making an ionic compound a conductor.

Answer 21

Free charge carriers by melting or dissolving in water.

Question 22

Definition of covelant bonding.

Answer 22

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

Question 23

Where does covelant bonding occur?

Answer 23

• Non metallic elements. (H2)
• Compounds of non metallic elements (H2O)
• Polyatomic ions (A group of atoms with a charge. NH4)

Question 24

Explain the difference between an ionic attraction and a covelant attraction.

Answer 24

The attraction of a covelant bond is localised, it only happens between the shared pair of electrons between the atoms. This results in molecules. Ions attract in all directions.

Question 25

Defininiton of a molecule.

Answer 25

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

Question 26

How are dot and cross diagrams drawn for covelant compounds.

Answer 26

Circles are joined (unlike ionically bonded atoms). Dot and cross lie between the intercection of the circles.

Question 27

How many covelant bonds can boron form?

Answer 27

Boron has 3 electrons in its outer shell. This means it can form three covelant bonds leaving its outer shell with only six electrons. (BF3) Electron deficient.

Question 28

How many covelant bonds can phosphorus form?

Answer 28

It has 5 electrons in its outer shell so it can form either three or five covelant bonds. As it is in period 3, its outer shell can have 18 electrons making five covelant bonds possible.

Question 29

What is expansion of an octect?

Answer 29

If an atom has paired each of its electrons in covelant bonds so it has more electrons than the nearest nobel gas, this is expansion of the octect.

Question 30

What is a dative covelant bond?

Answer 30

A covelant bond where the shared pair of electrons is supplied by one of the atoms involved in bonding only.

Question 31

Give an example of a dative covelant bond.

Answer 31

An ammonia molecule donates a loan pair of electrons to a H+ ion. A dative covelant bond is represented by a straight arrow instead of a line.

Question 32

What is the average bond enthalpy?

Answer 32

It is a measurement of a covelant bonds strength. Stronger bonds form between smaller atoms.

Question 33

What is a giant ionic lattice.

Answer 33

A network of ions attracting oppositely charged ions in all directions.