Topic 6: s & p Block Elements

Question 1

Electronegativity

Answer 1

An atoms ability to draw electron density towards itself

Question 2

Electronegativity can lead to … of a covalent bond where electron density is pulled towards the … atom.
This results in … .
A … bond with … like this is sometimes referred
to as having … .

Answer 2

polarization
most electronegative
partial negative and partial positive charges
covalent
partial charges
ionic character

Question 3

As well as effective nuclear charge and principle quantum number, electronegativity can depend on … and …

Answer 3

oxidation state
hybridization

Question 4

A … can polarise a … in an ionic bond so the ionic bond has …

Answer 4

cation
anion
covalent character

Question 5

The polarisability of an atom is …
Atoms are polarisable if …

Answer 5

its ability to be distorted by an electric field
the electron cloud can be distorted easily (often larger anions)

Question 6

We … see a purely ionic/covalent bond

Answer 6

rarely

Question 7

sp3 has a … electronegativity value than sp2

Answer 7

lower

Question 8

Metals form … oxides while non-metals form … oxides

Answer 8

basic
acidic

Question 9

Electronegativities of metals, metalloids and non-metals

Answer 9

Metals: < 1.9
Metalloids: 1.9-2.2
Non-metals: >2.2

Question 10

Requirements for something to be metal:

Answer 10

Partially filled band
Electrons delocalised so can move easily between orbitals

Question 11

Amphoteric

Answer 11

display basic and acidic behaviour

Question 12

Why are there favoured oxidation states?

Answer 12

For the s- and p-block, the most important factor determining oxidation state is a closed shell electronic configuration
Atoms prefer to follow the octet rule

Question 13

The favoured oxidation values tend to vary by …

Answer 13

+/- 2
Avoids radicals

Question 14

The favoured oxidation state … down the group as …

Answer 14

can change (lower)
there’s an increasing tendency for ns2 electrons to be left out of bonding so only used p electrons for bonding (inert pair effect)

Question 15

If it costs energy to promote an electron, how can it be energetically favourable?

Answer 15

More strong bonds can be formed

Question 16

How do electron promotion energies change down the group

Answer 16

general increase

Question 17

When atoms get larger, their bonds get …

Answer 17

weaker

Question 18

bond energy

Answer 18

the amount of energy required to break a bond into neutral atoms

Question 19

larger bond energy =

Answer 19

stronger

Question 20

…, … and … single bonds are … so go against the trend because …

Answer 20

N-N, O-O and F-F
weak
they’re small atoms so sit very close together in a single bond. This means their adjacent lone pairs experience significant repulsion

Question 21

Bonds tend to be … if the atoms are different sizes due to …

Answer 21

weaker
poor overlap

Question 22

Homonuclear bonds tend to be … than heteronuclear bonds

Answer 22

weaker

Question 23

Whether a reaction is favourable is based on …

Answer 23

the energy required to break bonds and released when forming them

Question 24

multiple bonding is common in … but … because …

Answer 24

the first of the p-block
not in the other rows
larger atoms have poorer p-orbital overlap so form weaker pi bonds

Question 25

Catenation definition It occur when ...

Answer 25

when elements prefer to form lots of single bonds, generating polymer- like structures homonuclear pi bonds are weak

Question 26

Some data tables show the bond energy of ... and ... separately so ...

Answer 26

sigma pi you may need to add them together

Question 27

If sigma > pi ... If pi > sigma

Answer 27

more likely to form catenated single bonds + be polymeric more likely to form double bonds + be molecular

Question 28

SiO2 exists in...

Answer 28

tetrahedral SIO4 units (single bonds)

Question 29

octet expansion

Answer 29

p-block elements that don't obey the octet rule

Question 30

hydrolysis involves the attack by ...

Answer 30

lone pair on O on H2O

Question 31

Why is the hydrolysis of SiCl4 more favourable than CCl4

Answer 31

CCl4 inert, SiCl4 readily hydrolyses Si has empty 3d orbitals (much higher in energy than 3d) Allows attack by lone pair on O from H2O C has empty 3d orbits but much higher than valence 2p orbitals, harder for lone pair to attack Si is larger than C so has more space + is more exposed to allow attack

Question 32

alkanes and silanes are ... unstable in an oxygen atmosphere but alkanes are ... stable as silicone ...

Answer 32

thermodynamically kinetically has accessable 3d orbitals allowing attack of O and there is less of a steric hindrance than around C

Question 33

pi backbonding can ...

Answer 33

shorten the bond and reduce the charge separation