Inorganic chem

Question 1

First ionization energy

Answer 1

The energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms

Question 2

Factors affecting ionization energy

Answer 2

• Nuclear charge
• Shielding
• Atomic radius

Question 3

What does a high ionization energy mean

Answer 3

There’s a strong attraction between the electron and the nucleus, so more energy is needed to overcome the attraction and remove the electron

Question 4

Why do ionization energies decrease down a group

Answer 4

• Electron in the outer shell is furthest away from the nucleus and more shielded due to increasing number of completed inner shells
• Weaker attraction to nucleus
  -Less energy required to remove the electrons

Question 5

Why does ionization energies increase across a period

Answer 5

-Each element has 1 extra electron in its outer shell and one extra proton in the nucleus
- As the elements are in the same period, the electrons are being added to the same shell
- Electron shielding stays the same across a period due to no extra inner shells
- But, as the nuclear charge increases, all the electrons experience a greater attraction to the nucleus leading to a decrease in atomic radius
- Therefore, more energy required to remove electrons

Question 6

two exceptions to the trend (increase across a period)

Answer 6

• Drop between groups 2 and 3 due to sub-shell structure
• Drop between groups 5 and 6 due to p-orbital repulsion

Question 7

Drop between groups 2 and 3

Answer 7

• The outer shell electron in group 3 is in a p orbital rather than an s orbital
• A p orbital has a slightly higher energy than s orbital in the same shell, so the electron is to be found further from the nucleus
• The p-orbital also experiences additional shielding
• Therefore, less energy required to remove outer p-electron from Group 3 compared to removing the outer s electron from group 2

Question 7

Drop between groups 5 and 6

Question 8

Why does reactivity increase down group 2

Answer 8

• Electrons are lost more easily
• Atomic radius increases so electrons further from the nucleus and more shielded by the increased number of completed inner shells
  -Therefore, despite the increase in nuclear charge, the electrons are less attracted to the nucleus so less energy required to remove elections

Question 9

What are group 2 compounds used for

Answer 9

• Calcium hydroxide is used in agriculture to neutralize acidic soils
• Magnesium hydroxide and calcium carbonate are used in some indigestion tablets

Question 10

Why does reactivity decrease down group 7

Answer 10

• Atomic radius increases so the outer electrons are further from the nucleus
• More shielded from the attraction of the +ve nucleus because they’re more inner electrons
• This makes it harder for larger atoms to attract the electron needed to form an ion

Question 11

Why does boiling point increase down group 7

Answer 11

• Increasing strength of London forces due to more electrons as the size and relative mass of the atoms increase
• Therefore, more energy required to overcome these forces

Question 12

Testing for halide ions

Answer 12

• Add dilute nitric acid to sample to remove carbonate ions that might interfere by also forming a ppt with silver nitrate
• Add silver nitrate solution, silver ions react with halide ions to form silver halide ppt’s
• Observe ppt color:
  Chloride = white ppt
  Bromide = cream ppt
  Iodide = yellow ppt

Question 13

Test for carbonate ions

Answer 13

If carbonates present, carbon dioxide will be released
Test for CO2 - limewater turns cloudy

Question 14

Test for sulfates with HCl and Barium chloride

Answer 14

White ppt means it will be barium sulfate

Question 15

Test for ammonium compounds with sodium hydroxide and litmus paper

Answer 15

Damp litmus paper turns blue

Question 16

Metallic bonding

Answer 16

multidirectional electrostatic attraction between regularly arranged positive metal ions and sea of delocalized electrons