Periodic Table

Question 1

Group no. indicates

Answer 1

No. of valence electrons

Question 2

Period no. indicates

Answer 2

No. of electron shells

Question 3

How does metal get a full valence shell?

Answer 3

Lose electrons

Question 4

How does non-metal get a full valence shell?

Answer 4

Gain electrons

Question 5

Physical properties of Group I metals

Answer 5

Low melting points
* soft - easily cut
* low densities

Question 6

Chemical properties of Group I metals

Answer 6

Reacts with water to form metal hydroxide & H2

Example:
2Li + 2H2O → 2LiOH + H2

2Na + 2H2O → 2NaOH + H2

2K + 2H2O → 2KOH + H2

Question 7

Trends of Group I metals

Answer 7

M.P. & B.P. decreases
* Density increases

Reactivity increases
* Fast rxn
* Very fast rxn, sparks
* Explosion

Question 8

Group VII Metals

Answer 8

Halogens; 7 valence electrons; diatomic

Question 9

Group I Metals

Answer 9

Alkali metals; 1 valence electron

Question 10

Physical properties of Group VII Metals

Answer 10

• cannot conduct electricity
• relatively low m.p. & b.p., density
• coloured

Question 11

Chemical properties of Group VII Metals

Answer 11

Displacement → a more reactive halogen will displace a less reactive halogen from an aqueous solution of its ions

• Example:
  Cl2 + 2KI → 2KCl + I2
• Observation:
  The colourless potassium iodide (KI) will form a
  black precipitate in a brown solution as iodine (I2)
  is formed.

Question 12

Trends of Group VII

Answer 12

M.P. & B.P.
increases
* Color
darkens
* Density
increases

Reactivity increases

Question 13

Group 0

Answer 13

Monoatomic; Noble Gases; unreactive as they have full valence shells; no need to form bonds with other atoms

Question 14

How are the elements
arranged in the Periodic Table?

Answer 14

According to proton number.

Question 15

Why are noble gases
unreactive?

Answer 15

They have full valence shell.

Question 16

State the differences
between alkali metals
and other metals.

Answer 16

Low melting/boiling points, low
density

Question 17

Explain why metallic
character decreases
across a period.

Answer 17

Across a period, the elements start from losing electrons to gaining electrons to form valence shell.

Hence, metallic character decreases.

Question 18

Using electronic
configurations, explain why potassium and
sodium are in the same group/have similar chemical properties

Answer 18

Sodium has a structure of 2.8.1 and potassium has a structure of
2.8.8.1.

Since potassium and sodium has the same number of valence
electrons, thus they are in the same
group.

Question 19

Describe the
observations of reactions of sodium with cold water.

Answer 19

It reacts violently on the surface of
the water.

Effervescence of colourless gas
produced which pops a lighted splint.