the periodic table

Question 1

what is meant by electronegativity

Answer 1

it is the ability of an atom to attract the shared pair of electrons in a covalent bond

Question 2

electronegativity across period 3 elements

Answer 2

Across period 3, nuclear charge increases.
Electrons are added to the same outermost electron shell and hence number of electron shells remain the same and shielding effect remains approximately constant.
Stronger electrostatic forces of attraction between the nucleus and the electron pair in the covalent bond.
Electronegativity increases.

Question 3

electronegativity in group 2 or group 17 elements

Answer 3

Down the group, nuclear charge increases.
Number of electron shells increases, which results in valence electrons further away and more shielded. Weaker electrostatic forces of attraction between the nucleus and the electron pair in a covalent bond. Electronegativity decreases

Question 4

structure / bonding of Na, Mg, Al
(period 3)

Answer 4

Giant metallic lattice structure
Strong metallic bonds - strong electrostatic forces of attraction between cations and sea of delocalised electrons in a giant metallic structure

Question 5

melting point of Na, Mg, Al
(period 3)

Answer 5

Metals have high melting points as a large amount of energy is needed to overcome the strong electrostatic forces of attraction between the cations and the sea of delocalised electrons in the giant metallic structure.
- Melting point generally increases across the period among metals
- Number of valence electrons per atom for metallic bonding increases and cationic radii decreases
- Larger amount of energy required to overcome the stronger electrostatic forces of attraction between the cations and sea of delocalised electrons

Question 6

structure and bonding of Si
(period 3)

Answer 6

Giant molecular structure
Strong covalent bonds - strong covalent bonding between atoms in a giant molecular structure

Question 7

melting point of Si
(period 3)

Answer 7

Si has a very high melting point.
Very large amount of energy required to overcome the strong and extensive covalent bonds between atoms in the giant molecular structure.

Question 8

electrical conductivity of Na, Mg, Al (period 3 metals)

Answer 8

Metals are good conductors of electricity due to the presence of sea of delocalised electrons as mobile charge carriers to conduct electricity in the giant metallic structure.
- Electrical conductivity generally increases form Na to Al
- Number of valence electrons contributed per atom for metallic bonding increases
- More delocalised electrons can act as mobile charge carriers.

Question 9

electrical conductivity of Si
(period 3)

Answer 9

Si is a semiconductor.
Si gives rise to delocalised electrons at high temperatures.
At higher temperatures, more electrons gain enough energy to overcome the nuclear attraction and electrical conductivity increases.

Question 10

structure & bonding of period 3 oxides
(Na2O, MgO, Al2O3, SiO2, P4O4, P4O10, SO2, SO3)

Answer 10

Na2O, MgO, Al2O3 :
giant ionic structure, strong electrostatic forces of attraction between oppositely charged __ & __ ions.

SiO2 :
giant covalent structure, strong covalent bonds between Si and O atoms.

P4O4, P4O10, SO2, SO3 :
simple molecular structure, weak idid / pdpd forces of attraction between __ molecules.