Metals Flashcards
Physical properties of most metals
High density, melting and boiling point
Exceptions to density
Group one metals are less dense than water
Exception to high melting and boiling point
Mercury is a liquid at room temperature and pressure
Appearance and durability of metals
Metals are good conductors of heat and electricity
They are also shiny, malleable and ductile
Why are pure metals not widely used?
They are soft and may corrode easily
What is an alloy?
A mixture of one or more elements, which may or may not be metal
Why are pure metals soft?
It is due to the regular arrangement of their atoms in neat layers which slide past each other easily when a force is applied
Why are alloys harder than pure metal?
In an alloy, the arrangement of atoms is disrupted by the presence of atoms of different sizes
This prevents the layers of atoms form sliding past each other easily, making the alloy harder than a pure metal
Displacement reactions of metals
Displacement reaction takes place when a more reactive metal is placed in the salt solution of a less reactive metal
The more reactive metal has a higher tendency to form ions, hence it displaces the less reactive metal from its salt
What if less reactive metal is placed in a salt solution of more reactive metal?
Then no observable change will be seen
Which metals react with cold water?
Violently: Potassium. Hydrogen gas catches fire and explodes
Violently: Sodium. Hydrogen gas may catch fire
Moderately: Calcium
Slowly: Magnesium
Which metals react with steam?
Violently: hot Magnesium reacts violently with steam and burns with a white glow
Aluminium reacts readily with steam but reaction slows down due to formation of a protective oxide layer
Hot zinc reacts readily with steam. Zinc oxide is yellow when hot and white when cold
Hot iron react slowly with steam
Metals which react violently with dilute hydrochloric acid
Potassium
Sodium
Calcium
Metals which react readily with dilute hydrochloric acid
Magnesium
Aluminium
Zinc (moderately fast)
Metals which react slowly with dilute hydrochloric acid
Iron
Why does lead not react with dilute hydrochloric acid?
Due to the formation of an insoluble layer of lead (II) chloride. The salt acts as a protective layer and prevents the lead from reacting further with the acid
Extraction of metals
Metals are usually found in nature as ores. A more reactive metal requires tougher methods of extraction than a less reactive metal
Metals extracted through heating with carbon
Zinc and metals below it in the reactivity series
Extraction of metals above zinc in reactivity series
Metals above zinc form very stable oxides that are not easily reduced
They can only be extracted from their ores through electrolysis of their molten oxides
Thermal stability of metal carbonates
Reactive metals such as potassium and sodium form very stable carbonates which do not decompose easily upon heating
Carbonates from calcium to copper decompose upon heating to form metal oxide and carbon dioxide
Thermal stability of silver carbonate
Silver carbonate is the least stable since silver metal is least reactive. It decomposes completely into silver metal and carbon dioxide.
Metal + cold water…
Metal hydroxide + hydrogen
Metal + steam…
Metal oxide + hydrogen
Reaction of metal with other metal oxides
A more reactive metal can displace (reduce) a less relative metal oxide
Iron and carbon
Form an alloy known as mild steel, used to make car bodies
Stainless steel
Made from iron, carbon, chromium and nickel
Used as medical instruments
