Topic 2 & 3

Question 1

Atomic Radius Trend

Answer 1

Increases down a group

Number of electron shells increases thus increasing in size

Shielding: core electrons prevents valence electrons from the nucleus, thus experiencing less attractive force

decreases across a period

As the number of protons and electrons increases, the attraction between the nucleus and the
outer electrons increases, pulling electrons closer to the nucleus resulting in a smaller radius

Question 2

Atomic Radius ____ down a group

Answer 2

increase

Question 3

Ionic Radius

Answer 3

• Cations are smaller than their neutral atoms
• Anions are larger than their neutral atoms

Question 4

Ionization energy (IE)

Answer 4

The energy required
to remove one electron from a gaseous
atom, measured by how tightly the outer
electrons are attracted by the nucleus.

Question 5

First ionization energy

Answer 5

the IE to take away the
first electron from the valence shell

Question 6

Trend of IE

Answer 6

Increases across a period
o The increase in nuclear charge across a period causes an increase in the attraction between the
outer electrons and the nucleus makes the electrons more difficult to remove
Decreases down a group
o The electron being removed is from the energy level furthest from the nucleus, removing valence
electrons further away becomes easier due to electron shielding

Question 7

IE increase corresponds to…
Large jump
Small jump
Tiny jump

Answer 7

o a new fully-filled inner shell (large jump)
o a new fully-filled subshell (small jump)
o a half filled subshell (tiny jump)

Question 8

Electron affinity (EA)

Answer 8

the change in energy when one mole of an electron is added to one mole gaseous
atoms.

Generally negative because the electron and the nucleus form an attraction. The
forming of an attraction results in the release of potential energy as heat, thus the enthalpy change is
negative.`

Question 9

Trend of EA

_____ across a period

____ down a group

Answer 9

Increases (negatively) across a period
o This is as a result of increasing attraction from the nucleus due to the increasing number of
protons and the reduced distance from the nucleus to the valence electrons

Decreases down a group
o The greater the distance between the nucleus and the outer energy level, the weaker the
electrostatic attraction and the less energy is released when an electron is added to the atom

Question 10

EA: Explain why elements in Group 17 have the most negative electron affinity.

Answer 10

Atoms are one electron away from fulfilling a full energy level

Question 11

EA: Deduce the nature of metal ions and non-metal ions with reference to ionization energy and electron
affinity

Answer 11

Metals form cations therefore having a lower IE (easier to lose e-) while non-metals form anions,
requiring an addition of electron (electron affinity is more negative)

Question 12

EA: Why is the second electron affinity for oxygen endothermic (energy is absorbed)?

Answer 12

The 2nd electron affinity corresponds to the addition of an electron to the O- ion. The O- ion has a
low proton to electron ratio and so the new electron is actually repelled by the electrons that are
already present, thus the 2nd electron affinity is positive as energy has to be put in to force the
electron onto the ion.

Question 13

EA: Why is fluorine an exception of the vertical trend?

Answer 13

The electrons in the outermost shell of a fluorine atom are closer together. The electron gained also
feels a great amount of repulsion from the electrons originally in the outermost shell. Energy is
required to keep the gained electron in the shell, causing fluorine to have a smaller electron affinity
than chlorine.

Question 14

Electronegativity

Answer 14

a measure of the attraction an atom has for a shared election

• attraction to pull e- toward itself

Question 15

trend of electronegativity

Answer 15

increase across a period, decrease down a group

Question 16

Explain the electronegativity trend across a period

Answer 16

Electronegativity increases across a period, this is as a result of increasing attraction from the nucleus due
to the increasing number of protons and the reduced distance from the nucleus to the valence electrons
(shielding electrons and proton/electron ratio are the same for elements in a period).

Question 17

Explain the electronegativity trend down a group

Answer 17

Electronegativity decrease down a group due to the increasing distance and shielding electrons.

Question 18

Metallic character

Answer 18

how easily an atom can lose electrons -

same as IE but differently interpreted

Question 19

trend of metallic character

Answer 19

decrease across period
increase down a group

Question 20

Relate and explain the metallic character trend across a period to IE and atomic radii

Answer 20

IE increases across a period due to having a higher
effective nuclear charge (proton/electron ratio) making it more difficult for atoms to lose electrons (less metallic)

Question 21

Relate and explain the metallic character trend down a group to IE and atomic radii

Answer 21

how easily an atom can lose electrons to form cations, low IE would correspond to high
metallic character as electrons experience less attraction from the nucleus due to shielding, and more electron shells

Question 22

Alkali metals

Configuration:
Reactivity ____ down the group:
Melting points ____ down the group
React readily with ___ to give an e-
Metal + water -
React vigorously w halogens to produce:

Answer 22

s1
increase
decrease
water
metal hydroxide + hydrogen gas
metal halide (ionic salt)

Question 23

Halogens
configuration:
Reactivity ___ down the group

Melting points___ down the group

Process of halogen reacting with halides (ions) to remove e-

Answer 23

Halogens
p5
decrease; outer shell gets further, weaker attration to acquire e-
Increase; intermolecular forces between halogen molecules increase down the group. strong forces - more forces need to overcome.
Oxidation

Question 24

Halogen - precipitation reaction occurs when ___ and ___ in aqueons solution combine to form an __

Answer 24

cation; anion; insoluble ionic solid

Question 25

Oxides
Acidity - ___ across a period generally due to ___
Acidity - tend to attract
Amphoteric refers to a molecule that ___

Answer 25

increases; increase in electronegativity
e-
acts as both an acid or a base

Question 26

Why does acidity increase with EN?

Answer 26

Acidity is the tendency to accept electrons. The higher the EN, the higher attraction there is, meaning that it would be easier to attract electrons towards itself (accept electrons.

Question 27

Electronegativity of aluminum is 1.6. Explain how it is amphoteric.

Answer 27

Aluminium has an electronegativity of 1.6. Exactly at the boundary where oxides of elements start becoming acidic, allowing them to behave both ways.

∆EN between aluminium and oxygen is also minimum.

Question 28

Describe and explain the general trend in melting point in the metals in periods 2 and 3

Answer 28

The melting point of the 3 first metals in periods 2 and 3 increases as the strength of the metallic bond
increases.

Question 29

b) Explain the reason for the peak in melting point in C (carbon) and Si (silicon)

Answer 29

Giant covalent bonding

Question 30

Atomic Radius ____ down a group

Answer 30

increase

Question 31

Atomic Radius ____ down a group

Answer 31

increase

Question 32

Relative atomic mass def