Zusammenfassung der Ressource
C5
- Air
- Dry air contains non metal elements such as: nitrogen oxygen and argon
- Air also contains small amounts of non-metal compounds such as: CO2 and water vapour
- Simple molecular substances
- Have very low melting and boiling points
- They are low because the intermolecular forces are weak
- Very little energy is needed to overcome the forces
- They have no free electrons moving around so they cant conduct electricity
- Ionic crystals
- The earths hydrosphere is all the water on earth
- Hydrosphere is mostly water with some salts
- When water evaporates dissolved salts from solid crystals
- Salts are ionic compounds. Ions have either a positive or a negative
charge and are arranged in a giant 3-D pattern called a lattice
- The strong force of attraction between positively charged
ions and negatively charged ions is called an ionic bond
- Ionic compounds have high melting and boiling points
- Because a large amount of energy is needed to
overcome the strong intermolecular forces in the lattice
- Ionic compounds do not conduct electricity when solid but do when they are
melted or dissolved in water because the charged ions can move
- Na+ and Cl- make NaCl; Mg2+ and Cl- make MgCl2
- SO4 2- is a molecular ion
- Testing for ions
- Solutions of some ionic compounds make a precipitate
of an insoluble compound when they mix.
- Calcium Ca2+
- White precipitate
- Copper Cu2+
- Light blue precipitate
- Iron(II) Fe2+
- Green precipitate
- Iron(III) Fe3+
- Red Brown precipitate
- Zinc Zn2+
- White precipitate
- Negative carbonate ions are identified by adding dilute acid and looking for fizzing
- Because CO2 is
released
- Negative chloride, bromide, iodide and sulfate ions are identified by adding
dilute silver nitrate or dilute barium chloride and looking for precipitates
- Metals minerals and ores
- The litosphere is the rigid outer layer of the earth made up of the crust and the upper mantle
- Minerals are solid with atoms or ions arranged in a regular arrangement or lattice
- Silicon oxygen and aluminium are very abundant in the litosphere
- Rocks contain metal minerals called ores
- Extracting metals by heating their oxides with carbon is a
redox reaction as both oxidation and reduction happen
- Burning metals can only be used for elements less reactive than carbon
- Diamond and Graphite
- They are giant carbon covalent structures
- Diamond
- Bonds are very strong and need a large amount of energy to break them.
This is why it has a high melting point and wont dissolve in water
- There are no free particles in diamond so it doesnt conduct electricity
- Each carbon atom has 4 bonds in a tetrahedral lattice
- Graphite
- Each carbon atom is strongly bonded to three others in sheets
- The sheets are strong but there is a weak bond between the layers so they can slide over eachother
- There are free moving electrons between the layers so it conducts electricity
- Formula mass
- The relative formula mass of a compound is the sum of the
relative atomic masses of all the atoms in its formula
- The gram formula mass of an element or compound is its relative atomic mass in grams
- percentage of metal in mineral = total mass of metal atoms/gram formula mass
- Electrolysis
- Passing a current through an ionic compound
when it is molten or dissolved in water
- The compound being broken down is called the electrolyte -
electrolytes break down as the current passes through them
- It is used to extract more reactive metals because their oxides cannot be reduced by carbon
- Metals form at the negative cathode because metals are positive ions
- Negative ions such as chloride and oxide move to the positive anode
- Metals
- Are malleable - can be hammered into shape
- The atoms are held by metalic bonds - atoms are
arranged in a regular pattern or giant lattice
- Metallic bonds are very strong and need a lot of energy to melt or reshape them
- The metal ions lose their outer shell electrons to form positive ions
in solid metals- this forms a sea of electrons that move around
- The attraction between the + ions and sea of electrons is so high - so metals have high melting and boiling points
- Metals conduct electricity as they have electrons that can move
- In pure metals, all the atoms are the same size and can roll over each other - so metals are malleable
- Environment
- Lead mercury and cadmium are poisonous
- Extracting and purifying metal ores needs a lot of energy
- They have a very small yield
- Some minerals contain sulphur and during extraction sulfur dioxide could be made