Periodicity And Ionisation Energy

Question 1

How is the periodic table arranged?

Answer 1

By increasing atomic number

Question 2

What do periods show?

Answer 2

Repeating trends in physical and chemical properties

Question 3

What do groups show?

Answer 3

Similar chemical properties

Question 4

What is periodicity?

Answer 4

Repeating trends in physical and chemical properties

Question 5

Which orbital has the highest energy electron in an S block element?

Answer 5

S orbital

Question 6

Which orbital has the highest energy electron in a P block element?

Answer 6

P orbital

Question 7

Describe the structure of giant metallic lattices?

Answer 7

Cations/metal ions arranged in fixed regular layers, with delocalised electrons free to move through the structure

Note:
The delocalised electrons stop the cations from repelling each other

Question 8

What are the properties of (most) metals/metallic lattices?

Answer 8

-strong metallic bonds
-high electrical conductivity
-high melting and boiling points

Question 9

Why can a metal conduct electricity when solid and liquid?

Answer 9

Because of the delocalised electrons that are free to move, carrying a charge

Question 10

Why does the boiling point increase from Na to Mg to Al?

Answer 10

-increased number of outer shells
-increased charge of metal ions arranged
-increased strength of metallic bonding: attraction between metal cation and delocalised electrons

Question 11

Why aren’t metals soluble?

Answer 11

Due to very strong metallic bonds

Question 12

What shape and bond angle is diamond?

Answer 12

Tetrahedral
109.5

Question 13

Describe the arrangement of graphite?

Answer 13

-Parallel layers of hexagonal arranged C atoms
-Weak London forces hold the layers together
-each C atom- 3 covalent bonds, forth electron delocalised between layers

Question 14

What is graphene?

Answer 14

A single layer of graphite with strong covalent bonds

Question 15

Give three components of silicon dioxide (silica,SiO2)

Answer 15

-strong covalent bonds
-main component of sand
-tetrahedral structure (like diamond)

Question 16

What are the properties of giant covalent structures?

Answer 16

-high melting/boiling points
-strong covalent bonds
-most compounds insoluble in water
-Most compounds do not conduct electricity (but some do)

Question 17

Graphite and graphene are an exceptions to covalent structures not conducting electricity. Why?

Answer 17

-hexagonal layer structure uses 3 of 4 outer shell electrons
-4th electron is delocalised (between layers of graphite) (across layers of graphene)
-electrons can carry the charge

Question 18

What happens to the melting point as you move from Group 1 to Group 14?

Answer 18

Melting point increases due to increasing strength (strong bonds)

Question 19

What is the trend in melting point between Group 14 and Group 15?

Answer 19

There is a decrease in melting point due to a transition from giant to simple molecular lattices

This change signifies a shift from strong bonding in giant lattices to weaker forces in simple molecular structures.

Question 20

What is the melting point trend from Group 15 to Group 18?

Answer 20

Melting points are low from Group 15 to Group 18

This trend is attributed to the presence of simple molecular lattices, which are held together by weak forces.

Question 21

Fill in the blank: The melting point _______ as you move from Group 1 to Group 14.

Answer 21

increases

Question 22

True or False: The melting point decreases when moving from Group 14 to Group 15.

Answer 22

True

Question 23

How to display the 1st ionisation energy as an equation

Answer 23

X(g) -> X+(g) + e-

Question 24

How to display 2nd ionisation energy as an equation?

Answer 24

X+(g) -> X2+(g) + e-

Question 25

How to display 3rd ionisation energy as an equation?

Answer 25

X2+(g) -> X3+(g) + e-

Question 26

What is ionisation?

Answer 26

The removal of one or more electrons ## Footnote The energy you need to remove the first electron is called the first ionisation energy

Question 27

Important points about ionisation energy

Answer 27

-ionisation energy measured in gaseous atoms so always use gas state symbol -always refer to 1 mole of atoms (as stated in definition) rather than to a single atom -the lower the ionisation energy the easier it is to form an ion

Question 28

What are the factors affecting ionisation energy?

Answer 28

-nuclear charge -atomic radius -shielding

Question 29

Describe what affect more shielding has on ionisation energy?

Answer 29

More shielding decreases nuclear attraction from the outer most shell so less energy would be required to remove an electron

Question 30

Describe the affect a higher atomic radius has on ionisation energy?

Answer 30

-Higher ATOMIC RADIUS decreases the nuclear attraction from the outermost shell (due to larger distance and shielding) meaning less energy is needed to remove an electron

Question 31

Describe the affect of a higher nuclear charge on ionisation energy?

Answer 31

The more protons in the nucleus, the stronger the attraction for the electrons making it harder to remove an electron

Question 32

Ionisation energy increases/decreases down a group?

Answer 32

Decreases

Question 33

Why does ionisation energy decrease down a group?

Answer 33

-larger atomic radius -more shielding -reduced nuclear attraction (due to more shielding)

Question 34

Does ionisation energy increase/decrease across a period

Answer 34

Increase

Question 35

Why does ionisation energy increase across a period?

Answer 35

-nuclear charge increases -smaller atomic radius (due to increased nuclear charge) Note: The extra electrons gained across a period are added to the outer energy level so doesn’t increase shielding

Question 36

What does increasing ionisation energy mean?

Answer 36

It gets harder to remove outer electrons

Question 37

What does decreasing ionisation energy mean?

Answer 37

It gets easier to to remove outer electrons

Question 38

What are the two exceptions to the trend of first ionisation energies?

Answer 38

-the first ionisation energy decreases between groups 2 and 3, and between groups 5 and 6 (Seen on the graph as small drops between those groups)

Question 39

Why is there a drop between groups 2 and 3? And explain?

Answer 39

Due to sub shell structure ## Footnote -the outer electrons furthest away in group 3 elements are in the P orbital rather than S orbital -P orbital slightly higher energy than S orbital in the same shell so electron is further from nucleus -P orbital has additional shielding from S electrons These factors override affect if increased nuclear charge so ionisation energy drops slightly

Question 40

Why is there a drop between groups 5 and 6? And explain?

Answer 40

Due to p orbital repulsion ## Footnote -In group 5 the electron is being removed from a singly-occupied orbital whereas group 6 the electron is being removed from an orbital containing two electrons - the repulsion between two electrons in an orbital means it’s easier to remove an electron

Question 41

Why does successive ionisation energies increase within each shell?

Answer 41

-Because electrons are being removed from an increasingly positive ion -also less repulsion amongst remaining electrons So electrons held more tightly

Question 42

Why does the number of delocalised electrons per atom in metals affect melting point?

Answer 42

The more there are the stronger the bonding will be and the higher the melting point (Mg2+ has two delocalised electrons per atom so it’s got a higher melting point than Na+ which only has one)

Question 43

What are the properties of ionic bonding?

Answer 43

-High melting/boiling points -Solid (standard temp and pressure) -Does not conduct electricity (solid) -Does conduct electricity (liquid) -Soluble in water

Question 44

What are the properties of simple molecular (covalent)