1.1 Periodic Table and Trends

Question 1

Recall the periodic Table Trends across periods and down groups (and definition) for:
- Atomic Radii

Answer 1

definition: effective nuclear charge (nuclear pull0 vs electron shielding

across: decreased nuclear charge with no change in electron shielding
down: though there is increased nuclear charge, the increase in electron shielding is more significant

Question 2

recall the periodic table trends across a period and down a group (and definition):
- Ionic Radii

Answer 2

down: increases
- effective nuclear charge stays constant and the number of shells increases as you move down a group

across: decreases
- as you move across a period, the number of occupied shells in the ions remains constant for species of the same charge but the effective nuclear charge increases. The valence electrons become more strongly attracted to the nucleus.
- anions are larger than cations in the same period

Question 3

recall the periodic table trends across a period and down a group (and definition):
- 1st ionization energy

Answer 3

definition: energy required to remove an electron from an atom

down: decreases
- effective nuclear charge stays constant, no of shells increases down a group, therefore the valence electrons are less attracted to the nucleus as they are further from it. Thus, the energy required to overcome the attraction between nucleus and valence electrons is less.

across: increases
- effective nuclear charge increases and no. of occupied shells remains constant across a period. Therefore, valence electrons become more strongly attracted to nucleus, meaning more energy is required to remove electrons.

Question 4

recall the periodic table trends across a period and down a group (and definition):
- electronegativity

Answer 4

definition: ability of an atom to attract electrons towards itself

down: decreases
- effective nuclear charge stays constant and number of shells increases down a group. therefore, the valence electrons are less strongly attracted to nucleus as they are further apart from the nucleus

across: increases
- number of occupied shells in atom remains constant but effective nuclear charge increases across a period. Thus, valence electrons become more strongly attracted to the nucleus

Question 5

compare trends:
- metallic behavior

Answer 5

metallic behavior:
- shiny
- malleable
- conductive
- high density
- high MP & BP

Question 6

compare trends:
- non-metallic behavior

Answer 6

non-metallic behavior:
- dull
- brittle
- not conductive (heat and electricity)
- low density
- low MP & BP

Question 7

Compare trends:
- reactivities of groups 1 (Li-Cs) (Alkali Metals)

Answer 7

• reactivity due to ability to lose electrons
• the biggest with the least electrons to lose = most reactive

Question 8

Compare trends:
- reactivities of group 17 (F-I) (halogens)

Answer 8

• reactivity due to ability to gain electrons
• the smallest with the least electrons to gain = most reactive

Question 9

oxides across a period:

Answer 9

oxides change from basic, through amphoteric to acidic across a period