Periodicity, Structure and Bonding

Question 1

Atomic Size

Answer 1

Distance from the centre of the atom to its edge

Question 2

Atomic Size Trend Along A Period

Answer 2

atomic size decreases due to the increased nuclear charge/more protons pulling the electrons within the same shell closer.

Question 3

Atomic Size Trend Down A Group

Answer 3

atomic size increases due to addition energy levels and electron shielding effect, the inner electrons shield the outer electrons from the pull of of the positive nucleus, therefore the outer electrons are further away

Question 4

Ionisation energy

Answer 4

energy required to remove one mole of electrons from one mole of atoms in the gaseous state.

Question 5

I.E along a period

Answer 5

ionisation energy becomes greater due to the increase in nuclear charge/more protons attracting the electrons within the same energy level. The energy therefore increase

Question 6

I.E down a group

Answer 6

ionisation energy decreases due to the electron energy levels and shielding effect. The outer electrons therefore experience less of the positive pull of the nucleus.

Question 7

Electronegativity

Answer 7

attraction an atom has for the shared pair of electrons in a covalent bond

Question 8

Electronegativity along a period

Answer 8

Electronegativity increases along a period, due to the the greater nuclear positive charge, due to an increase in protons, increases the pull on the outer electrons. The outer electrons are therefore more difficult to remove.

Question 9

Electronegativity down a group

Answer 9

Electronegativity decreases down a group as there are more energy levels and the outer electrons are further away form the nuclear positive charge. The pull on the outer electrons is less,hence Electronegativity decreasing.

Question 10

3 inter molecular forces

Answer 10

Permanent dipole-Permanent Dipole attraction, Hydrogen Bonding and London dispersion forces.

Question 11

Permanent dipole-Permanent Dipole

Answer 11

the electrostatic attraction between the oppositely charged dipole ends of two or more polar molecules.

Question 12

Permanent dipole-Permanent Dipole Molecule

Answer 12

will have higher mp and bp due to the greater inter molecular attraction, more energy is required to separate the molecule

Question 13

Spatial Arrangement Symmetrical

Answer 13

when the polar bond’s spatial arrangement is symmetrical then the molecules is non polar

Question 14

Spatial Arrangement Unsymmetrical

Answer 14

when the polar bond’s spatial arrangement is unsymmetrical then the molecule is polar

Question 15

To define Polarity or Non-Polarity

Answer 15

1. Check the difference in electronegativity
2. Determine if bonds are weak/strong covalent/ionic bonds
3. Check the shape
4. State polarity

Question 16

Hydrogen Bonding

Answer 16

Electronegativity difference between hydrogen and nitrogen or oxygen or fluorine is very large, which results in strong polar bonds that cause strong inter molecular attractions than simple PD-PD,

Question 17

How is London Dispersion Forces Caused

Answer 17

An uneven distribution of electrons can lead to a dipole which induce dipole on a nearby atom. The attraction of these 2 dipoles London Dispersion Forces

Question 18

How is London Dispersion Forces Affected?

Answer 18

the bigger the atom due to an increase in total number of electrons, the greater the London forces due to larger dipoles formed. Therefore increasing the energy required to desperate these molecules, hence increase in mp and bp

Question 19

Elements that have London Dispersion Forces

Answer 19

diatomic elements, noble gases, sulphur, phosphorous and fullerene.

Question 20

Non-polar London Dispersion Forces

Answer 20

Non-polar molecules will only have ldf’s
hydrocarbons such as alkanes and alkenes have only ldfs due to their symmetrical arrangement

Question 21

Noble Gases

Answer 21

insoluble and do not conduct
have low mp and bp due to weak London forces that exists between atoms, which are easily broken at low temperatures, hence the, are gases

Question 22

Diatomic Elements

Answer 22

Have non-polar covalent bonds within the molecules
These strong bonds don’t break during melting and boiling. They have LDF, which are weak, easily broken at low temps

Question 23

Molecular Solids

Answer 23

P4,S8,C60,I2
don’t conduct
Iodine has bigger atoms due to more electrons that lead to stronger LDF.
Phosphorous, Suplhur and Fullerene have more atoms hence stronger LDF’s

Question 24

Covalent Networks

Answer 24

solid at room but insoluble in water
graphite conducts due to only 3 out of 4 electrons bonding
Strong covalent bonds inside and outside

Question 25

Metallic Elements

Answer 25

Contain metallic bonding.
As the number of delocalized outer electrons increase, the hardness, mp and bp also increase. The strenght of the metallic bond increases with the increases attraction between the positive core and increasing number of delocalised electrons

Question 26

Covalent Radius

Answer 26

is half the length of the covalent bond, the distance between both nuclei in a covalent bond