Periodic Properties

Question 1

IUPAC nomenclature (100+)

Answer 1

0 - nil
1 - un
2 - bi
3 - tri
4 - quad
5 - pent
6 - hex
7 - sept
8 - oct
9 - enn

Question 2

Nuclear Charge

Answer 2

Measure of ability of protons to attract negative electrons

Question 3

Periods

Answer 3

Horizontal rows
There are 7

Question 4

Groups

Answer 4

Vertical columns
There are 18

Question 5

Which elements begins the 3d transition series

Answer 5

Scandium (Z = 21)

Question 6

Which element begins the 4d transition series

Answer 6

Yttrium (Z = 39)

Question 7

When does filling of 4f electrons begin

Answer 7

Z = 58 - Cerium

Question 8

Properties of s - block elements

Answer 8

• ns1 or ns2 outer config
• Reactive metals with low ionization enthalpies
• Lose 1+ or 2+ ions

Question 9

S block elements as we go down the group

Answer 9

• Metallic character increases
• Reactivity increases

Question 10

Which s-block elements are not ionic

Answer 10

Lithium and Beryllium

Question 11

P block elements outer config

Answer 11

ns2np1 and ns2np6

Question 12

P block character down the group and across

Answer 12

• Non - metallic character increases left to right
• Metallic increases as we go down

Question 13

D block elements outer config

Answer 13

(n-1)d (1-10) ns (0-2)

Question 14

Covalent Radius

Answer 14

Size of an atom that is part of a single - covalent bond

Question 15

Metallic Radius

Answer 15

Measurement of size of atom in relation to other metal elements

Question 16

Atomic Radius

Answer 16

Measures size of the atom; mean / typical distance from the center of the nucleus to the outermost isolated electron

Question 17

What happens to size across the period and why?

Answer 17

• Size usually decreases
• In the same outermost shell, added electrons do not screen each other.
• Hence, effective nuclear charge increases pulling electrons closer to the nucleus

Question 18

Factors affecting atomic radii

Answer 18

1. Increase in effective nuclear charge = Increase in attractive force
2. Increase in ionic character = Shorter bond = Lower atomic radii

Question 19

What happens to size down the group?

Answer 19

• Down the group the size increases
• The addition of the extra valence shell has a more pronounced effect on the size compared to the effect of the increase in nuclear charge

Question 20

Why is anion > parent > cation

Answer 20

• Anion is larger as addition of one or more electrons leads to increased repulsion among electrons and decrease in effective nuclear charge
• Cation is smaller as it has fewer electrons while nuclear charge is the same

Question 21

Isoelectronic species

Answer 21

Atoms and ions which contain the same number of electrons

Question 22

Ionization enthalpy

Answer 22

Energy required to remove an electron from an isolated gaseous atom in ground state

Question 23

Factors affecting ionization enthalpy

Answer 23

1. Larger size of atom = smaller ionization enthalpy
2. Higher screening effect = lower value of ionization enthalpy
3. Higher nuclear charge = Higher ionization enthalpy
4. Penetration effect - s > p > d > f

Question 24

Why do alkali metals have low ionization enthalpy

Answer 24

They have high reactivity

Question 25

Trend of ionization enthalpy and explanation

Answer 25

• Across period (it increases) - electrons are added in the same principal quantum number –> shielding does not increase that much to compensate for increased attraction
• Down the group (decreases) - electron added further from nucleus causing shielding to outweigh nuclear charge and removal of electron requires less energy

Question 26

Exceptions in trend in ionization enthalpy

Answer 26

1. Boron < Berrylium - Boron electron removed from 2s where 2s penetration > 2p
2. Oxygen < Nitrogen - Nitrogen has 2p3 stability and due to hund’s rule and symmetry it requires more energy to separate (Same reason for S < P)
3. Al < Mg

Question 27

Explain the deviation in ionization enthalpy with respect to
B, Al, Ga, In, Ti

Answer 27

• Decrease in B to Al is due to larger size of Al
• In Ga, as there are more 3d electrons, there is less screening causing an increase in effective nuclear charge
• Ti has very poor shielding as well (hence greater than In)

Question 28

Electron Gain Enthalpy

Answer 28

When an electron is added to a neutral gaseous atom to convert it into a negative ion

Question 29

Electron Gain Enthalpy across period

Answer 29

• Becomes more negative - Effective nuclear charge increases and harder to add an atom to a larger atom

Question 30

Electron Gain Enthalpy down the group

Answer 30

Becomes less negative as atom size increases and added electron is further from nucleus

Question 31

Exceptions of EA (Electron affinity / electron gain enthalpy)

Answer 31

• Cl > F –> Cl has a larger size, meaning less force of repulsion between electrons
• In group 16 –> S > Se > Te > Po > o
• Noble gases have positive EA

Question 32

Factors affecting EA

Answer 32

1. Higher atomic size = Lower EA
2. Higher effective nuclear charge = higher EA
3. EA decreases with increasing shielding effect
4. Half filled or completely filled orbitals

Question 33

Why is EA positive for noble gases

Answer 33

• Completely filled outer shell (highly stable)
• To gain another electron, they reequire energy
• Energy required to overcome electrostatic repulsion between added electrons and existing electron

Question 34

Electronegativity

Answer 34

Ability of an atom to attract shared electrons to itself

Question 35

Trend of electronegativity

Answer 35

• Across the period - Increase in non-metallic character = increase in electronegativity
• Down the group - Increase in metallic character = decrease in electronegativity

Question 36

On the basis of quantum numbers justify that the sixth period should have 32 elements

Answer 36

• The sixth period can have 6s, 6p, 5d, 4f as they are lesser energy than 7s
• Total number of orbitals found using (2l + 1) –> 1 + 3 + 5 + 7 = 16.
• Total electrons accommodated is multiplied by 2 => 32

Question 37

Diagonal Relationship

Answer 37

Behaviour of beryllium and lithium similar to Mg and Al

Question 38

Size of isoelectronic species is affected by

Answer 38

Nuclear charge

Question 39

Why does neon have a larger radius than flourine?

Answer 39

• due to the way atomic radii are measured for noble gases like neon and covalent radii for non-noble gases like fluorine.
• Noble gases, including neon, have van der Waals radii, which are typically larger than covalent radii. Van der Waals radii measure the distance between the center of the atom and the outermost point of the electron cloud, whereas covalent radii measure the distance between the nucleus and the bonding electrons