Ionisation energy and Periodicity

Question 1

How did Mendeleev affect the Periodic table?

Answer 1

-In 1869 he organised the 60 known elements by atomic mass -He lined up elements with similar properties - He left space for elements which were yet to be discovered and predicted their properties

Question 2

How is the Periodic table organised now?

Answer 2

• Elements are arranged according to atomic number
• In periods numbered 1 to 7 and by chemical properties in groups numbered 1 to 18

Question 3

What are groups 3-12?

Answer 3

Transition metals

Question 4

Define periodicity?

Answer 4

A trend that repeats across each period of the table

Question 5

Define electron configuration?

Answer 5

The distribution of electrons of an atom or molecule in atomic or molecular orbitals

Question 6

Define First Ionisation energy?

Answer 6

The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to make a mole of gaseous 1+ ions.

Question 7

What three factors effect the first ionisation energy?

Answer 7

1. Atomic Radius
2. Nuclear charge
3. Shielding

Question 8

How does Atomic Radius effect 1st ionisation energy?

Answer 8

• The greater the atomic radius, the lower the nuclear attraction
• Less enery is required to remove the electron
• So the 1st Ionisation energy will be lower

Question 9

How does Nuclear charge affect 1st ionisation energy?

Answer 9

• The more protons in the nucleus, the greater the nuclear charge
• Nuclear attraction increases
• More energy is required to remove the electron
• Ionisation energy will be higher

Question 10

How does Shielding affect ionisation energy?

Answer 10

• Filled inner shells exert a shielding effect drecreasing the nuclear attraction
• Less energy is required to remove the electron
• So ionisation energy will be lower

Question 11

Why is there an increasing trend in successive ionisation energies?

Answer 11

• Successive Ionisation energy increase in value
• Once an electron has been removed the remaining electrons experience greater nuclear attraction
• So more energy is required to remove the next electron.

Question 12

What do ‘jumps’ in ionisation energy graphs show?

Answer 12

They represent a new shell so can be used to deduce group number and number of shells

Question 13

Does atomic radius increase or decrease across period 3?

Answer 13

Decreases

Question 14

Why does the atomic radius decrease across period 3?

Answer 14

• Nuclear charge increases from Na to Ar
• Same shielding but more electrons
• so Nuclear attraction increases
• thus decreasing the atomic radius

Question 15

Why does ionisation enery increase across the periods?

Answer 15

• Nuclear charge increases
• Same shielding as electrons enter the same energy level
• Nuclear attraction increases
• More energy required to remove the 1st electron

Question 16

How is melting point patterned across the periodic table?

Answer 16

Increases from group 1-14

Decreases from group 15-18

Question 17

Why is this pattern in melting point seen in the periodic table?

Answer 17

• Mpt is affected by bond strength/ structure
• Na to Si form Giant Lattices with strong bonds between atoms
• P to Cl form simple covalent molecular structures with weak intermolecular forces between molecules
• Ar is a monoatomic gas
• stronger bonds require more energy to break

Question 18

What structure do Na,Mg and Al have?

Answer 18

Giant metallic lattice

Question 19

What structure does Si have?

Answer 19

Giant covalent lattice

Question 20

What structure does P, S, and Cl have?

Answer 20

Simple covalent molecular

Question 21

What structure does Ar have?

Answer 21

Monoatomic