Periodicity

Question 1

periodicity

Answer 1

repeated patterns in periodic table

Question 2

period

Answer 2

row across periodic table

Question 3

group

Answer 3

column down periodic table

Question 4

In what order are elements on periodic table arranged?

Answer 4

atomic number

Question 5

What do elements in the same period have?

Answer 5

outer electrons in same shell

Question 6

What do elements in the same group have?

Answer 6

same number of outer electrons

Question 7

As the number of protons increases…

Answer 7

attractions of electrons to nucleus increases

Question 8

As the number of full shells increases…

Answer 8

• repulsion is greater
• electrons pulled less strongly towards nucleus

Question 9

Trend in atomic radius across period

Answer 9

• same number of shells
• more protons electrons
• pulled more strongly toward nucleus
• radius decreases across period

Question 10

Trend in atomic radius down group

Answer 10

• more protons
• number of shells increases
• electrons repelled more
• less attraction to nucleus
• atomic radius increases down group

Question 11

Trend in ionic radius across period

Answer 11

• metallic ions lose electrons so have one fewer shell so size decreases non-metal
• ions gain electrons so have one more shell so size increases

Question 12

Trend in ionic radius down group

Answer 12

• protons increases
• shells increase
• ionic size increases because electrons held less tightly

Question 13

Trend in electronegativity across period

Answer 13

• more protons
• same number of shells
• greater attraction to nucleus

Question 14

Trend in electronegativity down group

Answer 14

• more protons
• more shells
• less attraction of electrons to nucleus

Question 15

electronegativity

Answer 15

ability to attract a pair of electrons towards self in covalent bond

Question 16

halogens

Answer 16

reactive group of non-metals in group 17

Question 17

noble gases

Answer 17

very unreactive family of non-metals found at extreme right-hand side in group 18

Question 18

alkali metals

Answer 18

reactive group of metals in group 1

Question 19

lanthanoides and actinoides

Answer 19

metals which make up first and second row of f block

Question 20

metalloid elements

Answer 20

have characteristics of both metals and non-metals

Question 21

trend in ionization energy across period

Answer 21

• increases
• effective nuclear charge increases
• increase in attraction between outer electrons and nucleus
• more difficult to remove electrons

Question 22

trend in ionization energy down group

Answer 22

• decreases
• electron is removed from energy level furthest from nucleus
• nuclear charge increases
• effective nuclear charge about the same (shielding of inner electrons)
• increased distance between electron and nucleus reduces attraction

Question 23

What accounts for the drop in IE between group 15 and 16?

Answer 23

• electron removed from group 16 element comes from doubly occupied p orbital
• easier to remove as it is repelled by partner

Question 24

Why do elements with valence electron in p orbitals have lower IE?

Answer 24

p orbitals have higher energy than s orbitals

Question 25

electron affinity

Answer 25

energy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous ions

Question 26

What is the equation for electron affinity of element X?

Answer 26

X(g) + e^- --\> X^-(g)

Question 27

Why do noble gases have no electron affinities?

Answer 27

generally do not form negative ions

Question 28

What is the second electron affinity for oxygen?

Answer 28

O^- + e^- --\> O^2-

Question 29

Is second electron affinity endothermic or exothermic? Why?

Answer 29

endothermic added electron is repelled by negatively charged ion energy needs to be available therefore for this to occur

Question 30

What is the EA for group 17?

Answer 30

* incomplete outer energy levels * high effective nuclear charge * attract electrons the most

Question 31

What is the EA for group 1?

Answer 31

* lowest effective nuclear charge * attract electron the least

Question 32

What is the EA for group 2 and 3?

Answer 32

* maximum EA * electron must be placed in p orbital further from nucleus * experiences reduced electrostatic attraction due to shielding

Question 33

What is the EA for group 15?

Answer 33

* added electron must occupy singly occupied p orbital * increased inter-electron attraction * attraction between electron and atom less