chem topic 1

Question 1

what is an isotope?

Answer 1

atoms of same element with same number of protons but different number of neutrons

Question 2

relative isotopic mass?

Answer 2

mass on one atoms isotope relative to 1/12 the mass of an atom of the isotope carbon -12

Question 3

relative atomic mass

Answer 3

average mass of an atom of an element relative to 1/12 the mass of a carbon 12 atom

Question 4

how does mass spectrometry

Answer 4

1. vaporise atom by vacuum
2. ionised by high energy electron gun
3. positive plates accelerate electron
4. ion deflected by magnetic field
   large deflection = low mass, high charge
   little deflection = high mass, low charge

Question 5

periodicity

Answer 5

repeating patterns of properties across a period

Question 6

1st ionisation energy

Answer 6

energy required to remove 1 mol of gaseous electron from 1 mol of gaseous atom to make 1 mol of gaseous 1 + ion

Question 7

factors affecting ionisation energy (3)

Answer 7

atomic radius / ionic radius
nuclear charge
shielding

Question 8

trend across period in ionisation energies?

Answer 8

N.C increases, shielding constant so radius decreases = greater attraction between valece e and nucleus so more energy required

Question 9

what is shielding

Answer 9

affect of core e reducing attraction between nucleus and valence e

Question 10

effective nuclear charge?

Answer 10

attraction felt by valence electrons

N.O protons -N.O core electrons

Question 11

exceptions to first ionisation energies in period 2

Answer 11

B has lower IE as electron now being removed from 2p subshell, further from the nucleus than the 2s subshell

O has lower ionisation energy as repulsion between paired e in one of the 2p subshells reduces attraction to nucleus

Question 12

successive ionisation energies

Answer 12

energy required to remove successive electrons from shells in atom

Question 13

trend in successive ionisation energy

Answer 13

general increase as e are being removed from ion with increasing effective nuclear charge so radius is smaller and there’s greater attraction between valence e and nucleus

big jumps due to e now being removed from shell closer to nucleus= less radius and less shielding

Question 14

1st ionisation energy trend down group

Answer 14

increased atomic radius and shielding outweighs increasing nuclear charge so less attraction between valence e and nucleus

Question 15

what happens when a gas is heated

Answer 15

e is promoted to higher energy level when excited by heat

e then relaxes back down emitting a photon of energy

Question 16

Cr electron config

Answer 16

1S2 2S2 SP6 3S2 3P6 4S1 3D5

Question 17

Cu electron config

Answer 17

1S2 2S2 2P6 3S2 3P6 4S1 3D10

Question 18

melting point trends across period

Answer 18

Li to B = metallic bonding between metal ions and sea of e (B has higher MP as B3+ has 3e- released whereas Li only goes to Li+ and 1 electron released)

C Giant covalent structure and covalent bonds

N - F = weak intermolecular forces

Ne = no intermolecular forces