Week 4

Question 1

Nuclear charge

Answer 1

Equal to the atomic number

Question 2

Facts about electron shielding

Answer 2

1. Electrons in a given shell are shielded by electrons in inner shells but not by electrons in outer shells
2. Inner filled shells shield outer electrons more effectively than electrons in the same sub-shell shields one another
3. Elements in the same period have the same shielding effect

Question 3

Core charge

Answer 3

The effective charge of the nucleus that is experienced by the outer shell electrons
Elements in the same group have the same core charge

Question 4

Measuring core charge

Answer 4

Atomic number minus the number of inner full shell electrons

Question 5

Atomic radius

Answer 5

The distance from the nucleus to the valence shell
The larger the effective nuclear charge, the more strongly held the electrons are and the smaller the atomic radius is.
Across the period as atomic number increases, atomic radius decreases.
Down a group, as atomic number increases, atomic radius increases as well.

Question 6

Atomic radius across a period

Answer 6

As atomic number increases across a period, the core charge increases as a result of constant shielding so the orbital containing the electrons is compressed and the atomic radius decreases.
Electrons added to same outer shell

Question 7

Atomic radius down a group

Answer 7

As atomic number increases down a group, atomic radius also increases because greater shielding effect and constant core charge, therefore valence electrons are well shielded from the nucleus. So electrons are less strongly attracted to the nucleus.
Electrons added to different outer shells

Question 8

Patterns in groups

Answer 8

Atomic size increases
Metallic character increases
Electronegativity decreases

Question 9

Atomic size increases

Answer 9

Down a group
Less stronger attraction between nucleus and valence shells
Valence electron shell not pulled strongly towards the nucleus
Distance between the nucleus and valence shell increases down the group

Question 10

Metallic character increases

Answer 10

Down a group

Because of less stronger attraction, it is easier to remove outer shell electron and this is a metallic behaviour

Question 11

Electronegativity

Answer 11

The ability of an atom to attract electrons toward itself

Question 12

Electronegativity decreases

Answer 12

Down a group

As atomic radius increases, attraction power of the nucleus towards an electron decreases

Question 13

Patterns in period

Answer 13

Atomic size decreases
Metallic character decreases
Electronegativity increases