T1- p Block LP1

Question 1

What is the difference between metals, nonmetals and metalloids when talking about conductivity?

Answer 1

Metals are good conductors and as you cool them down conductivity goes up. Metalloids are semiconductors. And nonmetals are generally isulators.

Question 2

What is the most abundant element in the Earth’s crust?

Answer 2

Oxygen

Question 3

What is second most abundant element in the Earth’s crust?

Answer 3

Silicon

Question 4

What is ionisation energy?

Answer 4

The energy required to remove completely an electron from the gaseous atom or molecule in its ground state.

Question 5

What is electron affinity?

Answer 5

The energy released when a gaseous atom, moecule or ion its ground state gains an electron.

Question 6

Why ionisation energy is positive?

Answer 6

Because the process generally requires an input in energy.

Question 7

Why electron affinity is negative?

Answer 7

Because process is normally favourable and energy will be given out.

Question 8

What is ionisation energy trend accros the periodic table?

Answer 8

Ionisarion energy increases from left to right and decreases from top to bottom. There is a sharp drop in energy when we start a new row.

Question 9

What affects ionisation energy?

Answer 9

The distance between the nucleus and the electron. The longer the distance the smaller the electrostatic attraction. This makes it easier to remove an electron.

Question 10

Why boron has a lower first ionisation energy than predicted?

Answer 10

It is because the single 2p electron is effectively shielded by the pair of 2s electrons. Also, when you remove 2p electron we get a full shell which is more stable.

Question 11

Why oxygen has a lower first ionisation energy than predicted?

Answer 11

In oxygen two electrons must pair up in a p orbital and so they experience a greater Coulombic repulsion. On ionisation this repulsion is relieved.

Question 12

What is Coulombic repulsion?

Answer 12

The repulsive force between two positive or two negative charges.

Question 13

Why gallium has a higher first ionisation energy than predicted?

Answer 13

It is because gallium is preceded by the first set of d orbitals that are weakly shielded. Thus electrons are hold tighter than expected.

Question 14

Why thallium has a higher first ionisation energy than expected?

Answer 14

It is because thallium is preceded by the first set of f orbitals that are weakly shielded. Thus electrons are hold tighter than expected.

Question 15

Why noble gases have negative electron affinities?

Answer 15

Noble gases already have a full shell. It is not favourable to add an electron to the next s shell.

Question 16

What is general trend of electron affinity when going down the group?

Answer 16

Electron affinity decreases with exeption to B, C, N, O, F.

Question 17

Why elements in group 15 have a lower electron affinity than expected?

Answer 17

Group 15 elements have a half filled p orbital. By adding an electron we casing a coulimbic repulsion between two electrons that needs to be overcome.

Question 18

Why group 1 has positive electron affinity and group 2 pas negative?

Answer 18

It is because adding electron to group 2 adds electron into the next p orbital which is higher in energy.

Question 19

Why 3p and 4p, 5p and 6p elements have simillar electron affinity?

Answer 19

It is caused by shielding effects of 3d and 4f block occurance. They are weakly shielded and holds electrons tighter.

Question 20

Why 1st row has lower electron affinity than 2nd?

Answer 20

It is due to small size, so get a high charge to radius ratio which gives high Coulombic and inter-electron repulsions.

Question 21

What is electronegativity?

Answer 21

Electronegativity is the ability of an atom to attract electron density towards itself in a molecule.

Question 22

From what to what Pauling’s scale goes?

Answer 22

From 0 to 4.

Question 23

How to calculate Pauling Electronegativity?

Answer 23

We get a molecule XY and compare measured and theorethical bond energies. ΔBond Energies= (X-Y)measured -(X-Y)expected. If Δ=0, X and Y have identical electronegativities. If electronegativities are different, we get a polar molecule.

Question 24

What is general trend of electronegativity across the periodic table?

Answer 24

Electronegativity increases from left to right and decreases from top to bottom.

Question 25

What changes electronegativity?

Answer 25

It vary depending of what is bonded to the element, the oxidation state and the hybridisation.

Question 26

Why electronegativity of sp>sp2>sp3?

Answer 26

The more s character the tighter electrons are held.

Question 27

What we put on y-axis of van Arkel Ketelaar triangle?

Answer 27

Difference in electronegativity.

Question 28

What we put on x-axis of van Arkel Ketelaar triangle?

Answer 28

Sum of the electronegativity divided by the number of atoms.

Question 29

What is this?

Answer 29

van Arkel Ketelaar triangle.

Question 30

What is the equation for Pauling electronrgativity?

Answer 30

X_A is the Pauling electronegativity of the more electronegative element and EAB is the bond dissociation energy for the heteronuclear covalent bond.

Question 31

If a substance is composed of elements with very similar electronegativities and the sum of the electronegativities dividing by the number of atoms is low, which type of bonding would you expect?

Answer 31

Metallic