Topic 3: Periodicity

Question 1

Effective nuclear charge

Answer 1

given by the atomic number and increases between succesive elements as protons are added to the nucleus/
- ability of an atom to attract increases with group number but remain the same down a group

Question 2

Electron affinity

Answer 2

the energy change when 1 mole of electrons is added to one mole of gaseous atoms

X(g) + e- —> X-(g)

Question 3

Ionization Energy

Answer 3

energy require to remove one mole of electrons from one mole of gaseous atoms in their ground state

• measure of attraction between nucleus and outer electrons

Question 4

Electronegativity

Answer 4

ability of an atom/nucleus to attract electrons in a covalent bond/molecule.

• It is an artificial scale from 0.7 to 4.0, created by combining the ionisation energy and the electron affinity of the elements.

Question 5

Alkali

Answer 5

bases soluble in water which from a basic solution (hydroxide ions)

Question 6

Group

Answer 6

(down) elements with the same number of valence electrons

Question 7

Period

Answer 7

(across) The period number (n) is the outer energy level that is occupied by electrons.

Question 8

Atomic Radii

Answer 8

half the distance between the nucleus’s of 2 bonded atoms of the same element

-atomic radii decrease along a period as the nuclear charge increases and electrons are added
to the same outer shell. The attraction between the outer electrons and nucleus increases.

Question 9

Ionic Radii

Answer 9

: Cations are smaller than their parent atoms, as the formation of positive ions involves the loss of
the outer shell.

Question 10

Group 1

Answer 10

S; Alkali Metals; reactive metals

Question 11

Group 17

Answer 11

P; Halogens; reactive group of non-metals

Question 12

Group 2

Answer 12

S; alkaline earth metals

Question 13

Group 18

Answer 13

P; Noble gases; stable non metals

Question 14

groups 3-12

Answer 14

D; transition metals

Question 15

transition metals

Answer 15

The transition metals are in the large section of d-block elements in the middle of the Periodic Table from Sc
to Zn, etc. Zn is not a transition metal because it does not form ions with incomplete d sub-levels.

Question 16

metalloid

Answer 16

• has physical and chemical features of non metals and metals are are in the P block of the periodic table along the staircase

Question 17

presence of inner electrons

Answer 17

reduces the attraction of nucleus to the outer electrons

Question 18

nuclear charrge as period crosses left to right

Answer 18

one proton is added to nucleus; one electron added to calance energy shell= effective nuclear charge increases with nuclear charge as there is no change in number of inner electrons

Question 19

nuclear charge down a group

Answer 19

• increase in nuclear charge= increase in number of inner electrons
• remains more or less the same down a group

Question 20

IONIC radii trend

Answer 20

• positive ions are smaller than parent ions (Na+ smaller than Na)
• negative ions larger than parent ions (Cl- larger than Cl)
• ionic radii decrease from Groups 1-14 fo rpositive ions (increased attraction between nucelus and electrons pulls outer shell closer to nucleus)
• ionic radii decrease down Group 14-17 for negative ions (decrease in ionic radii due to icnrease in nuclear charge across period)
• ionic radii decrease down a group as number of electron energy level increases

Question 21

two general trends of ionization energies

Answer 21

• ionization energies increase across a period
  (due to increase in effective nuclear charge that causes an increase in attraction between outer electrons and nucleus; makes electrons harder to remove)
• ionizzation energies decrease down a group
  (electron removed is from the energy level furtherest form nucleus; effective nuclear charge about the same; increased distance between electrons and nucleus reduces attraction between them)

Question 22

electron affinity trends

Answer 22

• g17 elements have incomplete outer energy levels; high effective nuclear charge; attract electrons the most
• g1 metals have low effective nuclear charge + attract electrons the least

Question 23

electronegativity trend

Answer 23

• increases across period due to increase in nuclear charge (increase attraction between nucleus and bond electrons)
• decreases down a group (bonding electrons are furthest from nucleus; reduced attraction)

Question 24

G1 Trend

Answer 24

• melting point decreases down group (attractions decrease with distance due to delocalized outer electron and positive ion attractive forces)
• reactivity increases down group (francium highest)

Question 25

G17 Trends

Answer 25

• melting point increases down group (london forces increase with size)
• reactivity decreases down group (Fluorine highest)

Question 26

melting points across period

Answer 26

• rise with maximum at G14, then fall at minimum to g18

Question 27

Alkali metals physical properties

Answer 27

• good conductors of electricity and heat
• low densities
• grey shiny surfaces

Question 28

Alkali metals chemical properties

Answer 28

• very reactive metals

- form ionic compounds with non metals

Question 29

Noble Gases

Answer 29

• colorless gases
• monoatomic (exist as single atoms)
• very reactive
• stable octet (complete valence energy levels with 8 electrons)

Question 30

Alkali reactions with water

Answer 30

produce hydrogen and a metal hydroxide

Question 31

Halogen physical properties

Answer 31

• colored

- show gradual change from gases, to liquid, to solids

Question 32

Halogen chemical propeties

Answer 32

• reactive non metals
• reactivity decreases down group
• form ionic compounds with metals
• form covalent compounds with other non metals

Question 33

halogen reaction with group 1 metal

Answer 33

-form ioinic halides (halogen atom gains one electron from group 1 elements to form halid ion X-)

Question 34

Displacement reaction

Answer 34

the more reactive halogen displaces the ions of the less reactive halogen form its compounds

Question 35

period 3 oxide acidity trend

Answer 35

basic —> amphoteric—> acidic

Question 36

bonding of period 3 oxides

Answer 36

giant ionic–> molecular covalent—> giant covalent
(METALLIC TO NON METALLIC CHARACTER)
- oxides become more inoicn down a group as electronegativity decreaes
-conductivity decreases across period
-oxidation state increases across period

Question 37

oxides of metals

Answer 37

ionic and basic

Question 38

oxides of non metals

Answer 38

covalent and acidic

Question 39

amphoteric oxide

Answer 39

show both acidic and basic properties

e.g. Aluminum Oxie

Question 40

Basic Oxide reaction with water

Answer 40

form alkaline solutions

form salt and a water

Question 41

Acidic Oxide reaction with water

Answer 41

form acidic solutions

form acids

Question 42

Ionic or covalent giant strutures

Answer 42

high melting point

Question 43

Molecular covalent structures

Answer 43

low melting points