period 3. Flashcards
steadWhy is sodium more reacting than magnesium?
= lower ionisation energy
= energy required to remove an electron from sodium is lower than magnesium, more energy needed for mg to react
What happens when sodium reacts with cold water?
= vigourously
= ball + fizzing
= gas produced is h2
= NaOh
what happens when mag nesiym reacts with cold water?
= slowly
= weak alkaline solution of mg(Oh)2, sparingly soluable, little oh- ions
reacts faster with steam, forming magnesium oxide, MgO
What happens when period 3 elements react with oxygen?
= oxides
What is formula for sodium oxide?
= Na2O
= na +1
= O 2-
= reacts fast with air
What is formula for magnesium oxide?
= MgO
mg2+
O2-
= very fast
What is the formula for alluminium oixde?
Al2O3
Al 3+
O-2
= slow (fast if powdered)
What is the formula of silicon dioixde?
SiO2
= slow
What is the reaction for phosphorous and oxygen?
= p4 + 5o2 => p4O10
= spontaneously combusts
What happens when sulfur reacts with oxygen?
S + O2 => So2
= oxidation number of +4
= with higher teperayire and ctaalyst So3 can be made, +6
= steadily burns
Why does Na2O MgO and Al2O3 have high melting points?
= forms solid ionic lattices, there are strong electrostatic forces of attraction between oppositley charged ions
= mgO has a higher boiling and melting point, as it forms a 2+ ions, therefore, attracted more strongly to oxygen
Why does Al2o3 have a lower melting point?
= Al3+ ion distorts electron cloud of oxygen, this means there is some polarisation, there is some covalent character, pulls the electrons from the oxygen to itself, less energy is required to break the bonds
Why does sio2 have a large melting and boiling point?
= sio2 is a large macromilecular structyre, htere are many covalent bonds, these are strong andrequire a great deal of energy to break,
Why is p4o2 and so2 have low melting anf boiling points?
= form simple molecular structures, weaker intermolecular forces (vanderwall forces) between the molecules, therefore requires little energy to break
What happens when ionic oxides are added to water?
= forms alkaline solutions
= contain o2- ions, this is a proton acceptor from water molecules when dissolved,
= oxide + water forms a hydroxide
=