Patterns in the Periodic Table

Question 1

How are elements arranged in the Periodic Table?

Answer 1

arranged in order of
increasing proton (atomic) numbers

Proton (Atomic) number: no. of protons in the nucleus of an atom
Nucleon (Mass) number: no. of protons & neutrons in the nucleus of an atom

Question 2

How do we classify the Elements in the Periodic Table?

Answer 2

Metals & Non-metals & Metalloids
- Metals on the left and middle
- Non-metals on the right (inclusive of hydrogen)
- Metalloids near dividing line (exhibit both metallic and non-metallic properties)

Question 3

group 1

Answer 3

alkali metals

Question 4

group 17

Answer 4

halogens

Question 5

group 18

Answer 5

noble gases

Question 6

groups 3-11

Answer 6

transition metals

Question 7

how are elements in same grp related

Answer 7

same grp, same no. of valence es, similar chemical properties

metals lose es -> cations
non-metals gain es -> anions

Question 8

group trends (3)

down the group

Answer 8

1. electron shells increase
2. atomic size increase
3. distance of v.e. away from nucleus increase

down grp

Question 9

how are elements in same period related

Answer 9

1. same period, same no. of valence shells
2. es UP, electrostatic forces of attention between nucleus & ve UP
3. ve pulled closer to nucleus, atoms SMALLER

Question 10

period trends (3)

across left to right

Answer 10

1. increase non-metallic properties, decrease metallic properties
2. protons no. increase
3. atomic radius decrease

across period

Question 11

why atoms decrease in size across period

Answer 11

• sheilding effect same (replusion from es in inner shells)
• electrons increase, electrostatic forces of attraction between nucleus and valence electrons increase
• v.e. pulled closer to nucleus, atoms smaller

Question 12

grp 1 unique trait

Answer 12

very reactive, found in nature as compounds only

Question 13

grp 1 physical properties (3)

Answer 13

1. soft, can be cut easily
2. low density (increase down)
3. low m.p. + b.p. (decrease down)

Question 14

grp 1 chemical properties (4)

Answer 14

1. +1 charge, -1 ve
2. react EXPLOSIVELY w/ h2o
   - 2 X (s) + 2 h2o (l) -> 2 XOH (aq) + h2 (g)
3. react w/ acid -> salt + h2o
4. tarnishes when exposed to air (oxidise), stored in oil

Question 15

grp 17 unique trait

Answer 15

share one v.e. to form one single covalent bond, diatomic molecules

Question 16

grp 17 physical properties (3)

Answer 16

1. low mp & bp (UP down grp, gas -> liquid -> solid)
2. coloured (intensity UP down grp)
3. soluble in h2o

Question 17

grp 17 chemical properties (3)

Answer 17

1. strong oxidising agents, gain es easily
2. more reactive halogen displaces less reactive halogen from halide sol
3. reaction w/ metals: 2 X (s) + Y2 (g) -> 2 XY (s)

Question 18

grp 18 physical properties (2)

Answer 18

1. low mp & bp
2. all COLOURLESS GASES at rtp

Question 19

grp 18 chemical properties (3)

Answer 19

1. chemically unreactive/inert
2. fully filled e shells
3. MONOATOMIC, individual atoms

Question 20

grp 3-11 physical properties (4)

Answer 20

1. high mp (except MERCURY)
2. high densities (smaller radii = more atoms in transition than alkali)
3. good electrical conductors
4. react to form coloured compounds (most SILVER/GREY)

Question 21

grp 3-11 chemical (2)

Answer 21

1. variable oxidation states (diff changes)
2. catalysts

Question 22

metalloids

Answer 22

near dividing line, exhibit both metal & non-metal properties