Trends in Periodic Table

Question 1

What is Core charge?

Answer 1

The magnitude of positive charge experienced by valence electrons

How strong the positive charge of nucleus attracts valence electrons

Question 2

How is core charge calculated?

Answer 2

Atomic number - Number of inner shell electrons

Question 3

Describe trend of Core charge in Periodic table

Answer 3

• Same core charge within a group
• Core charge increases moving right

Question 4

What is atomic radius

Answer 4

Size of atom - distance from nucleus to valence electron

Question 5

Describe trend of atomic radius in Periodic Table

Answer 5

• Increases going down
• Increases going left

Question 6

Explain the cause for why Atomic Radius trend in periodic table is seen:

Answer 6

• Radius increases going down as more electron shells are added, adding volume
• Radius decreases going right as core charge is greater; hence stronger attraction between nucleus to valence electrons pulls valence shell closer

Question 7

Describe trend of Ionsiation Energy in periodic table

Answer 7

• Decreases down
• Increases going right

Question 8

What is Ionisation Energy?

Answer 8

The minimum amount of energy required to remove an electron from an atom

Question 9

Describe why the trend in ionisation energy is observed

Answer 9

• Elements down a group have valence shells further away from nucleus; thus electrons are more losely bound and can be removed with less energy (lower ionisation energy)
• Elements from left to right show a greater core charge, thus valence electrons are more tightly held/bound and require greater energy to be removed (higher ionisation energy)

Metals want to donate electrons = low ionisation energy

Question 10

What is electronegativity?

Answer 10

The ability of an atom to attract electrons

Question 11

Describe trend of electronegativity in periodic table

Answer 11

• Increases going up
• Increases going right

Question 12

Describe why the trend in electronegativity in periodic table is observed

Answer 12

• Going up, the atomic radius is lower and thus nucleus has a greater positive attractive force on electrons
• Going across from left to right, core charge increases meaning nuclueus will have greater positive attractive force on electrons

Question 13

Describe the trend of reactivity of metals in periodic table

Answer 13

• Increases going down
• Decreases going left