Shapes, IMF’s, Periodicity, Qualtiative Tests, Group 2 And Group 7

Question 1

Name the shape of a molecule with 3 bonding pairs

Answer 1

Triganol planar

Question 2

Name the shape with 5 bonding pairs

Answer 2

Triganol bipyramidal

Question 3

When explaining bond angles, what do electrons do?

Answer 3

Electron pairs repel and move as far away from each other as possible to minimise repulsion

Question 4

Which repel more bonding or lone pairs?

Answer 4

Lone pairs

Question 5

What is the shape of a ammonia molecule

Answer 5

Triganol pyramidal

Question 6

Define electro negativity

Answer 6

The ability of an atom to attract the bonding electrons in a covalent bond

Question 7

Which elements/compounds have giant covalent structures?

Answer 7

Carbon
Silicon
Boron
Silicon dioxide

Question 8

How do induced dipoles form

Answer 8

The uneven distribution of electrons creates an instantaneous dipole which is induced onto neighbouring molecules

Question 9

What factor determines the strength of induced dipoles?

Answer 9

Amount of electrons

Question 10

What needs to be shown on a diagram of hydrogen bonds

Answer 10

Lone pairs
Dipoles
H-bond

Question 11

Which elements can form h bonds?

Answer 11

Nitrogen
Fluorine
Oxygen

Question 12

Do molecules with or without branches have higher boiling points?

Answer 12

Unbranched have higher boiling points due to each compound having more points of contact with another

Question 13

Which bond is stronger C=O or C-O

Answer 13

C-O

Question 14

Is HCl4 polar?

Answer 14

No as the dipoles cancel out

Question 15

What happens to reactivity down group 2

Answer 15

Down group 2, sheilding and atomic radius increase so nuclear attraction decreases. This means less energy is required to remove the electrons

Question 16

From left to right across a period, explain why more energy is needed to remove an electron

Answer 16

There is increased nuclear charge, therefore nuclear attraction which decreases atomic radius. As electrons join the same shell, shielding is nearly constant.

Question 17

What do successive ionisationenergies look like

Answer 17

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

Question 18

What is the ionic equation for any neutralisation

Answer 18

OH- + H+ -> H2O

Question 19

What ph do group 2 hydroxides have

Answer 19

10-12

Question 20

What is the test for a carbonate and what is the result

Answer 20

Add an acid
Effervescence (fizzing)

Question 21

What is the test and result for ammonium?

Answer 21

Add NaOH and heat
Turns damp red litmus paper blue

Question 22

Test and result for sulphate

Answer 22

Add barium chloride or barium nitrate
White ppt

Question 23

Test and results for halide tests

Answer 23

Add silver nitrate
Cl = white ppt
Br = cream ppt
I = yellow ppt

Question 24

What is the order of the qualitative tests and why

Answer 24

CaSH ( carbonate, sulphate, halide)
To stop false positives

Question 25

Define first ionisation energy

Answer 25

The energy needed to turn 1 mole of gaseous atoms into 1 mole of gaseous 1+ ions

Question 26

What is 1m3 in dm3

Answer 26

1000dm3

Question 27

What is the ideal gas equation

Answer 27

Pressure (pa) x Volume (m3) = 8.314 x mole x temperature (k)

Question 28

Steps to work out a half equation

Answer 28

1. Balance everything but O and H
2. Balance O by adding H2O
3. Balance H by adding H+
4. Balance charge by adding electrons