Unit 1-6 Flashcards
What does the period represent?
The number of shells
What does the group represent?
The number of valence electrons
What is the structure of metalloids?
Giant molecular: Infinite lattice structure
What type of bonding is involved in a metalloid?
Covalent: Very strong attraction between atoms due to the attraction between nuclei and shared electrons
What are the properties of metalloids?
Very high melting point
Poor conductivity
What is the structure of non-metals?
Simple molecular: Discrete molecules
What type of bonding is involved in a non-metallic structure?
Molecular (Van-Der-Waals): Weak forces between molecules
What are the properties of non-metals?
Low melting point
Nil conductivity
Why is the conductivity of metalloids considered to be poor?
Because some structures (graphite) are electrolytes but most aren’t
How do oxides of metals react?
Oxides of metals are basic
React with water to form alkali solutions
Will react with acids
How do oxides of metalloids react?
Oxides of metalloids are amphoteric
Can act as acidic oxides by reacting with bases
Can act as basic oxides by reacting with acids
How do oxides of non-metals react?
Oxides of nonmetals are acidic
React with water to form acidic solutions
Will react with bases
Reaction of group 1 elements with water
How does lithium react with water?
Moves slowly on the surface of water
Fizzes as H2 is formed
2Li(s)+2H2O(l)LiOH(aq)+H3(g)
Reaction of group 1 elements with water
How does sodium react with water?
Turns into a sphere
Moves quickly on the surface of water
Fizzes as H2 is formed
2Na(s)+2H2O(l)NaOH(aq)+H3(g)
Reaction of group 1 elements with water
How does potassium react with water?
Catches fire and burns with a lilac flame
Moves very quickly on the surface of water
Fizzes as H2 is formed
2K(s)+2H2O(l)KOH(aq)+H3(g)
Reaction of group 2 elements with water
How does magnesium react with water at room temperature?
Very slow and little reaction
Mg(s)+2H2O(l)Mg(OH)2(aq)+H2(g)
Reaction of group 2 elements with water
How does magnesium react with water at when heated in steam?
A white flash produces H2
White powder of MgO forms because the HO thermally decomposes
Reaction of group 2 elements with water
How does calcium react with water?
Steadily fizzes as H2 is produced
A cloudy white suspension is formed
The Ca(OH)2 formed is only slightly soluble
Ca(s)+2H2O(l)Ca(OH)2(aq)+H2(g)
Reaction of group 1 elements with oxygen
How does lithium react with oxygen?
Red flame burns brighter and more vigorously with oxygen
White powder of lithium oxide is formed
4Li(s)+O2(g)2Li2O(s)
Reaction of group 1 elements with oxygen
How does sodium react with oxygen?
Yellow/orange flame burns brighter in oxygen
White powder of sodium oxide is formed
4Na(s)+O2(g)2Na2O(s)
Reaction of group 1 elements with oxygen
How does potassium react with oxygen?
Lilac flame burns brighter in oxygen
White powder of potassium oxide is formed
4K(s)+O2(g)2K2O(s)
Reaction of group 2 elements with oxygen
How does magnesium react with oxygen?
Bright white flame burns brighter in oxygen
White powder of magnesium oxide is formed
2Mg(s)+O2(g)2MgO(s)
Reaction of group 2 elements with oxygen
How does calcium react with oxygen?
Brick red flame burns brighter in oxygen
White powder of calcium oxide is formed
2Ca(s)+O2(g)2CaO(s)
What type of agent are metals?
All metals are reducing agents
Need to lose their valence electrons as they react
What block do metals belong to?
The S block
What is the general formula of group 2 carbonates?
All have the formula XCO3
What is the solubility of group 2 carbonates?
Insoluble in water
How do group 2 carbonates react with dilute acids?
Metal Carbonate+Acid→Salt+Carbon Dioxide+Water
What are the control variables for thermal stability?
- Same number of moles of carbonate
- Same concentration and volume of lime water
- Flame distance
- Stop heating as soon as the same cloudiness is reached
What is thermal decomposition of group 2 carbonates?
Decomposing with heat in order to give oxide and carbon dioxide
XCO3(s)XO(s)+CO2(g)
How is limewater used to investigate thermal decomposition?
Limewater turns milky due to the formation of CaCO3
Speed indicates rate of reaction
Slows down the group since elements become more thermally stable
What is the general formula of group 2 hydroxides?
All have the formula X(OH)2
What happens to the solubility of group 2 hydroxides down the group?
Become more soluble upon descending the group
Magnesium is completely insoluble
Calcium hydroxide is cloudy since calcium is partially soluble
Strontium hydroxide is colourless since strontium is completely soluble
How do group 2 hydroxides react with dilute acids?
Base+Acid→Salt+Carbon Dioxide+Water
What is the thermal decomposition of group 2 hydroxides?
Decomposing with heat in order to give oxide and steam
Ca(OH)2(s)CaO(s)+H2O(g)
What happens to thermal stability down the group?
Increases down the group
More energy needed to decompose compounds
Describe the pH of oxides and hydroxides of group 1
Stronger bases than oxides and hydroxides of group 2
Higher pH values
What are the uses of magnesium hydroxide?
Used as a digestion anti-acid medicine
Useful due to weakly basic nature
Neutralises excess acid
What are the uses of calcium hydroxide?
Agriculture to alter soil and lake pH
Strong base
What are the uses of sodium hydroxide (caustic soda)?
Paper, soaps and ceramics
An alkali cleaner to treat aluminium before anodising
Neutralising of acids to make salts
