Periodicity Flashcards
Info on silicon
A semi-metal (metalloid), conducts electricity to some extent
Info on sodium, magnesium and aluminium
Shiny, conduct electricity and react with dilute acids to give hydrogen and salts
What is a metalloid
A semi-metal
What is another name for a semi-metal
A metalloid
Info on phosphorus, sulphur and chlorine
Non-metals, don’t conduct electricity, have low melting and boiling points
Info on argon
Noble gas, chemically unreactive, exists as separate atoms
Which 3 elements in period 3 react with water
Sodium, magnesium and chlorine. Reaction with sodium is vigorous, sodium floats on surface of water and fizzes rapidly, melting because of the heat given out by the reaction, strong alkaline solution of sodium hydroxide formed (pH 12-14). Reaction with magnesium very slow at room temp, resulting solution less alkaline (pH 9-10) as magnesium hydroxide is sparingly soluble meaning only a few hydroxide ions are produced.Reaction is much faster with heated magnesium and steam and gives magnesium oxide and hydrogen
Period 3 elements react with oxygen in which type of reaction
Exothermic reaction
Reaction of sodium and oxygen
Burns brightly with yellow flame to form white sodium oxide
Reaction of magnesium and oxygen
Strip of magnesium ribbon burns with bright white flame, forms white powdered magnesium oxide. White fumes given off. Magnesium is oxidised and oxygen is reduced
Reaction of aluminium and oxygen
Aluminium powder heated then lowered into a gas jar of oxygen, burns brightly to give aluminium oxide, a white powder. Aluminium= reactive metal, always coated with a strongly bonded surface layer of oxide which protects from further reaction. Means it can be used for everyday purposes saucepans, window frames etc. if surface scratched the exposed aluminium reacts rapidly with air and seals off surface
Reaction of silicon and oxygen
Forms silicon dioxide
Reaction of phosphorus and oxygen
Red phosphorus must be heated before it will react with oxygen. White phosphorus spontaneously ignites in air and white smoke of phosphorus pentoxide given off. Red and white phosphorus allotropes of phosphorus, same element with atoms arranged differently. If supply of oxygen is limited phosphorus trioxide is also formed
What are allotropes
The same element with the atoms arranged differently
Example of allotropes
Red and white phosphorus
Reaction of sulphur and oxygen
Sulphur powder heated, lowered into gas jar of oxygen, burns with blue flame to form colourless gas sulphur dioxide (and a little sulphur trioxide also forms). Misty, choking fumes of sulphur dioxide given off
Metal oxides structure
Form giant ionic lattices where bonding extends throughout compound, resulting in high melting points. The bonding in aluminium oxide is ionic but has some covalent character as aluminium forms very small ion with large positive charge so can approach the oxygen ions closely and distort its electron cloud
Non-metal oxides structure
Silicon dioxide has giant covalent structure, bonding extends through giant structure, high melting point due to strong covalent bonds. Phosphorus and sulphur oxides exist as separate covalently bonded molecules (simple molecular). Phosphorus oxides are solids, intermolecular forces are weak Vdw and dipole-dipole forces, melting points low
Which 2 oxides are insoluble in water
Aluminium oxide
Silicon dioxide
Why is sodium more reactive than magnesium
It takes less energy to lose one electron than it does to lose 2. So more energy is needed for magnesium to react
What is the pH of NaOH
14
What is the pH of H3PO4
1-2
Predict whether the melting point of lithium oxide is higher than, equal to or lower than the melting point of sodium oxide. Explain
Higher, the Li+ ion is smaller than the Na+ ion. It attracts the O2- group more strongly
Explain why sodium oxide reacts to form an alkaline solution when added to water
Basic oxide, the oxide ions (O2-) reacts with water forming OH- ions (NaOH formed)
Suggest one reason why a thin layer of aluminium oxide protects aluminium from corrosion in moist air
It is insoluble in water
