Chapter 2

Question 1

What is energy levels?

Answer 1

Each electron in an atom has its particular average amount of energy. The further away the electron is from the nucleus, the more energy it has. Each principal energy level (symbol n) corresponds to an electron shell at a certain distance from the nuleus. Energy levels are split up into sub-levels which are given the names s, p, d, & f.

Question 2

What is electronic configuration?

Answer 2

A way of reprensenting the arrangement of the electrons in atoms showing the principal quantum shells, the sub-shells and the number of electrons present, e.g. 1s^2 2s^2 2p^3. The electrons may also be shown in boxes.

Question 3

What is first ionisations energy?

Answer 3

The energy needed to remove 1 mole of electrons from 1 mole of atoms of an element in the gaseous state to form 1 mole of gaseous ions.

Question 4

How much electron can be put in every shells?

Answer 4

Shell 1: up to 2 electrons
Shell 2: up to 8 electrons
Shell 3: up to 18 electrons
Shell 4: up to 32 electrons

Question 5

What is successive ionisation energies?

Answer 5

The energy required in each step to remove the first electron, then the second, then the third, and so on, from gaseous atoms.
Note: you should be able to write equations for each of these. e.g.
1st ionisation energy: li(g) –> li+(g) + e-
2nd ionisation energy: li+(g) –> li 2+(g) + e-
3rd ionisation energy: li 2+(g) + e-

Question 6

What cause ionisation energy increase?

Answer 6

The net positive charge on the ion gets greater as each electron is removed. As each electron is removed there is a greater attractive force between the positively charged electrons which means that it need more energy to overcome these attractive forces.

Question 7

What cause the big difference between some successive ionisation energies?

Answer 7

Nitrogen occurs between the 5th and 6th ionisation energies. For sodium, the big difference occurs between the 1st and 2nd ionisation energies. These large changes indicate that for the second of these two ionisation energies the electron is being removed from a principal quatum shell closer to the nucleus.

Question 8

Explain the factors that influence ionisation enery!

Answer 8

The size of the nucleus charges: as the number of protons increases, the positive nucleur charge in the nucleus increases. the bigger the positive charge, the greater the attractive force between the nucleus and the electrons which make ionisation energy increase.
Distance of outer electrons from the nucleus: the attractive force between positive and neagtive charges decrease as the distance between them increase cause the ionisation energy needed decrease.
Shielding effect of inner electrons: The greater shielding of outer electrons by the inner electron shells, the lower the attractive forces between the nucleus and the outer electrons which cause the ionisation energy lower.
spin pair replusion: electrons are repel each other if in the same atomic orbital in a sub-shell. the increased replusion make it easier to remove an electron which make ionisation decreased.

Question 9

What is shielding?

Answer 9

The ability of inner shell electrons to reduce the effect of the nucleur charge on outer shell electrons.

Question 10

What is sub-shells?

Answer 10

Regions of the principal quantum shells where electrons exist in defined areas associated with particular amounts of energy. They are named s, p, d, & f.

Question 11

What is atomic orbitals?

Answer 11

Regions of space outside the nucleus that can be occupied by a maximum of two electrons. orbitals are named s, p, d, and f. They have different shapes.
s – one orbital
p – three orbitals
d – five orbitals

Question 12

What is the shape of s, p, and d?

Answer 12

s have spherical shape
p have hourglass with two lobes shape
d have the electron probability cloud for one type of d orbital has two pieces: it is like modified p orbitals with a ring around the middle.

Question 13

What is spin pair replusion?

Answer 13

A pair of electrons in the same orbital repel each other because they have the same charge. Pairing the spinning electrons so they spin in opposite directions reduces the replusion. The replusion is more than that of single electrons in separate orbitals. That is why the electrons in the p and d orbitals go into seperate orbitals before being paired up.

Question 14

What is free radical?

Answer 14

A species with one (or sometimes more than one) unpaired of electron.

Question 15

What is atomic radius?

Answer 15

The covalent atomic radius is half the distance between the nuclei of two covalently bonded atoms of the same type. This is not the only type of atomic radius but it gives us the best data when comparing the elements across a period.

Question 16

What cause the atomic increase down any group and decrease across any period?

Answer 16

Increase down any group: The more shell of electron cause the atomic radius increase.
Decrease across any period: The more nuclear and electron, increase the attractive force cause the atomic radius decreased.

Question 17

What cause the attraction force increases or ionisation increases down a group?

Answer 17

• The nuclear charge increases
• The distance between the nucleus and the outer electron remains reasonably constant / increases
• The shielding by inner shells remains reasonably constant or shielding by complete inner sells increases
• The two factors outweigh the increased nuclear charge.

Question 18

What cause the attraction force decreases?

Answer 18

• The distance between the nucleus and outer -electron increases.
• The shielding by inner shells increases.
• These two factors outweigh the increased nuclear charge.

Question 19

There is slightly decrease in ionisation energy between beryllium and boron. Why this happen?

Answer 19

There is less attraction between electron and the nucleus in boron is because:
- The distance between the nucleus and the outer electron increases slightly
- The shielding by inner shells increases slightly
- These two factors outweigh the increased nuclear charge.

Question 20

There is slightly decreases in ionisation energy between nitrogen and oxygen. What causes this?

Answer 20

Oxygen has one more proton than nitrogen cause the ionisation energy in oxygen decreases, However, the spin pairing cause the repulsion between a pair of electrons in this orbital results in less energy being needed to remove an electron. In conclusion, ionisation energy of oxygen lower is because of spin-pair replusion.

Question 21

The magnitude of ionisation energy is depends on four things, what are those?

Answer 21

• The distance of the electron from the nucleus
• The number of positive charges in the nucleus
• The degree of shielding of outer electrons by inner electrons shells
• Spin-pair replusion

Question 22

What cause ionic radius increase down any group and decrease across a period?

Answer 22

Increase down any group: Increase the shell of electrons, increase effect of inner shell electrons shielding the outer shell electrons cause the ionic radius to increase.
Decrease across a period: same with atomic radius, increase the nuclear charge attracts and the electrons, increased the attractive force cause the ionic raadius increased.