Inorganic 4: Period 3 Flashcards
Describe properties of sodium.
Alkali metal
Highly reactive
Forms NaO when exposed to air
Forms a giant metallic lattice
Strong electrostatic FOAs with delocalised electrons and positive ions
Good conductor of heat and electricity
Describe properties of magnesium.
Alkali earth metal
Light and strong
Used in alloy wheels
Describe properties of aluminium.
Metal
Poor conductor
Lightweight
Describe properties of silicon.
Metalloid
Semi-conductor
Used in computer chips
Describe properties of phosphorous.
Non-metal
Forms phosphate compounds
Found as P4(s) at room temperature
Describe properties of sulfur.
Non-metal
Bright yellow solid at room temperature
Found as S8
Describe properties of chlorine.
Non-metal halogen
Highly reactive
Toxic gas
Diatomic
Describe properties of argon.
Noble gas
Monatomic
Colourless and inert
Poor conductor
Describe the general trend in melting points across period 3.
Why does the melting point increase from sodium to aluminium?
Charge on the ion increases.
Stronger electrostatic forces of attraction.
Smaller ionic radius.
Higher charge density.
Why is the melting point of silicon so high?
Silicon forms a giant covalent lattice.
Very high melting point due to many strong covalent bonds.
Require more energy to break.
Why does sulfur have a higher melting point than phosphorous?
Sulfur is found naturally as S8, whereas phosphorous is found as P4.
So sulfur has more electrons and much stronger van Der Waal forces of attraction.
Why are the melting points of chlorine and argon lower than sulfur?
Because they have less weaker van Der Waal forces of attraction due to less electrons.
Less energy needed to overcome forces.
Describe sodium oxide.
Na2O
Giant ionic lattice
Forms NaOH in water
Completely dissolves
Basic oxide
Describe magnesium oxide.
Giant ionic lattice
Forms Mg(OH)2 in water
Describe aluminium oxide.
Strongest giant ionic lattice
Some covalent character
Amphoteric (reacts with both acids and alkalis)
Completely insoluble in water
Define amphoteric.
Reacts with both acids and alkalis
Describe silicon dioxide.
Giant covalent lattice
Completely insoluble
Describe phosphorous oxide.
Simple covalent molecule
Forms phosphoric acid (triprotic) in water
Strong van der Waals due to lots of electrons
Describe sulfur dioxide.
Basic oxide
Simple covalent molecule
Weak van der Waal and dipole-dipole forces of attraction
Bent, 117 bond angle
Forms sulphuric acid in water
Describe the reaction of sodium with water and give the equation.
Na(s) + 2H2O(l) –> 2NaOH(aq) + H2(g)
Reacts vigorously
Floats on the surface and fizzes rapidly
Melts due to heat released in reaction
Strongly alkaline NaOH formed
Describe the reaction of magnesium with water and give the equation.
Mg(s) + H2O(l) –> Mg(OH)2(aq) + H2(g)
Very slow
Only a few bubbles of hydrogen form
Describe the reaction of magnesium with steam and give the equation.
Mg(s) + 2H2O(g) –> MgO(s) + H2(g)
Much faster
Gives off MgO and hydrogen gas
Describe the reaction of chlorine with water and give the equation.
Cl2(g) + H2O(g) –> HCl + HClO
Disproportionation
Dissolves giving very pale green solution