Period 3 Elements Flashcards
Which is the most reactive: sodium, magnesium, or aluminum, and why?
sodium is the most reactive as it loses 1 electron to form a sodium ion while magnesium and aluminum lose 2 and 3 electrons respectively. Sodium is the most reactive as it takes less energy to lose 1 electron than it does for 2 or 3.
How does sodium react with water?
It will react vigorously with cold water, producing H2 gas and sodium hydroxide (making it an alkaline solution)
How does magnesium react with water?
It reacts very slowly with cold water and forms a weakly alkaline solution and a thin coating of magnesium hydroxide forms on the surface of the metal. But magnesium reacts much faster with steam to form magnesium oxide.
What happens when period 3 elements react with oxygen?
They form oxides with the metal being in their highest oxidation state except SO2
What is needed to make an oxide of sulfur with the highest oxidation state?
You need a high temperature and catalyst (vanadium catalyst)
What is the reaction of the period 3 elements in air?
sodium - vigorous
magnesium - vigorous
aluminium - slow
silicon - slow
phosphorus - spontaneously combusts
sulphur - burns steadily
What is the trend in the melting point of period 3 oxides?
From Na-Mg it increases
From Mg-SO2 it decreases
Why does MgO have a higher melting point than Na2O?
Mg forms 2+ ions, so bonds more strongly than the Na 1+ ions
Why does MgO have a higher melting point than Al2O3?
The difference in electronegativity between Al and O is not as great as Mg and O so the bonding is weaker.
Why does SiO2 have a higher melting point than other non-metal oxides?
It has a giant macromolecular structure. So there are lots of covalent bonds which require a lot of energy to break.
Why do P4O10 and SO2 have lower melting points than the other non-metal oxides?
They have relatively low melting points because they form simple molecular structures which are bound with weak intermolecular forces which take little energy to break.
What are the types of period 3 oxides in relation to pH?
Na and Mg: basic
Si, S, and P: acidic
Al: amphoteric
Which period 3 oxides form alkaline solutions?
Both Na2O and MgO form hydroxide solutions which means it is alkaline. Sodium hydroxide is more soluble in water so it forms a more alkaline solution.
What period 3 oxides form acidic solutions?
The simple non-metal oxides Phosphorus and sulfur form acidic solutions.
(the giant covalent structure of silicon dioxide means that it is insoluble in water but it will react with bases to form salts so it is classed as acidic)
What period 3 oxides are amphoteric?
Aluminum oxide is partially ionic and partially covalently bonded, it is also insoluble in water. but it will react with bases and acids to form salts.
