chapter 16: periodic table

Question 1

why is there an increase in metallic properties as you go down a group?

Answer 1

• going down a group, the size of an atom increases
  > valance electrons of an element will be further away from the attractive force of the nucleus
  > an element further down the group will lose its valence electrons more easily

Question 2

what are the physical properties of alkali metals?

Answer 2

• they are soft and can be cut easily
• they have low melting and boiling points
• they have low densities
  > eg. lithium, sodium and potassium float on water

Question 3

how do the metallic properties change down a group?

Answer 3

• there is an increase in metallic properties and a decrease in non metallic properties
• going down a group, the size of the atom increases
  > the valence electrons of an element will be further away from the attractive forced of the nucleus
  > element further down the group will lose its valence electrons more easily

Question 4

period number of an element is the same as…

Answer 4

• the number of electron shells

Question 5

the group number of an element is the same as…

Answer 5

• the number of valence electrons in an element

Question 6

how do the physical properties of alkali metals change going down group 1?

Answer 6

• the melting and boiling points decreases
• the density of alkali metals generally increase
• reactivity increases
  > the size of the atom increases, making it easier to lose valence electrons

Question 7

what are the chemical properties of alkali metals?

Answer 7

1. they are highly reactive metals
   > stored in oil to prevent it from reacting with air and water
2. alkali metals react with cold water to form an alkali and hydrogen gas
   > eg. lithium + water > lithium hydroxide + H2
3. they are powerful reducing agents
4. alkali metals form ionic compounds

Question 8

what do alkalis react with, are, and what do they form?

Answer 8

1. alkalis react with cold water to form alkali and hydrogen gas
2. alkalis are powerful reducing agents
3. alkali metals form ionic compounds

Question 9

what are halogens and what are their physical properties?

Answer 9

• halogens are non-metals that exist as diatomic covalent molecules
  > they have low melting and boiling points
  > they are coloured
  eg. chlorine: greenish-yellow gas
  bromine: reddish-brown liquid
  iodine: purplish-black solid

Question 10

how do the physical properties of halogens change going down the group?

Answer 10

• their melting and boiling points generally increase
• the colours of the halogens becomes darker
• reactivity decreases

Question 11

what are the chemical properties of halogens?

Answer 11

• halogens are reactive non metals
• they are in group VII
  > have 7 electrons and only needs to gain one more for a stable electronic configuration of a noble gas
• halogens reacts with most metals to form halides

Question 12

what reactions do halogens
undergo and what type of agents are they?

Answer 12

1. halogens undergo displacement reactions with halide solution
   > DISPLACEMENT REACTIONS: a reaction in which one element takes the place of another in a compound
   > a more reactive halogen with displace a less reactive halogen from its halide solution
2. halogens are powerful oxidising agents
   - during chemical reactions, atoms of halogens readily gain electrons to form halide ions with a charge of -1

Question 13

what is the order of reactivity of halogens?

Answer 13

• the reactivity of halogens decreases down the group
  > the size of the atom increases down the group making it more difficult for the nucleus to attract one more electron

Question 14

what are the properties of noble gases?

Answer 14

-noble gases are non metals
> are monoatomic
> colourless gases at room temperature
> have low melting and boiling points
> are insoluble in water
>are unreactive

Question 15

why are noble gases unreactive?

Answer 15

• they have fully filled electron shells
  > do not need to lose, gain or share electrons
  > they rarely react to form compounds

Question 16

what are the properties of transition metals?

Answer 16

1. they have high boiling and melting points and high densities
2. transition metals have variable oxidation states
   eg. - chromium (Cr): +3, +6
   - manganese (Mn): +2, +4, +7
   - iron (Fe): +2, +3
   -copper (Cu): +1,+2
3. transition metals form coloured compound
4. transition metals and their compounds are good catalysts