Periodicity

Question 1

what is periodicity

Answer 1

the study of trends within the periodic table. Often linked to elements electronic configurations

Question 2

What is the trend in atomic radius along a period

Answer 2

atomic radius decreases

Question 3

why does the atomic radium decrease along a period

Answer 3

• due to an increased nuclear charge
• same number of electron shells
• means that the outer electrons are pulled close to the nucleus as the charge produces a greater attraction
• atomic radius reduced

Question 3

what is the trend in atomic radius down a group

Answer 3

increases

Question 4

why does the trend in atomic radius increase down a group

Answer 4

• more electron shells
• increases distance between the outer electrons and the nucleus so weaker force of attraction
• increase electron shielding

Question 5

what is the trend in ionisation energy along a period

Answer 5

increases

Question 6

why does the ionisation energy increase along a period.

Answer 6

• atomic radius decreases
  -increase nuclear charge
• outer electrons are held more strongly so more energy required to remove the outer electron and ionise atom.

Question 7

What is the trend in ionisation energy going down a group

Answer 7

energy decreases

Question 8

why does the ionisation energy decrease down a group

Answer 8

• weaker FOA between nucleus and outer electrons
• shielding increases
• less energy required to remove outer electron

Question 9

what does the melting point of period 3 elements depend on

Answer 9

• structure of element
  -bond strength

Question 10

what happens to melting points across period 3 between sodium and aluminium

Answer 10

• all metals with metalliic bonding
• increase due to greater positive charge of their ions
• more electrons are released in the form of free electrons
• increasing electrostatic forced
• more energy needed to break

Question 11

Why does the melting points increase dramtically for silicone in period 3

Answer 11

• very storng covalent structure
• more energy required to break the strong covalent bonds
• high melting point

Question 12

why does the melting point decrease in period 3 between P and Cl

Answer 12

• all simple covalent molecules with weak VDW
• less energy is needed to overcome these weak intermolecular forces
• low melting points

Question 13

why does argon have an even lower melting point than Cl

Answer 13

• Argon is a noble gas that exists as individual atoms with a full outer shell of electrons
• makes atom every stable
  -VDW forces very weak
• less energy requried to overcome weak VDW forces so argon exists as a gas at room temp