C5 Flashcards
What is the atmosphere made up of in terms of the proportion of the main gases?
78% nitrogen (N), 21% oxygen (O), 1% argon(Ar), 0.04% carbon dioxide(CO^2)
How are atoms in molecules held together? and how do they work?
By covalent bonds, a covalent bond forms when atoms share a pair of electrons, this happens as the negatively charged pair of electrons are attracted to both positively charged nuclei
What are boiling points of simple molecular substances? why?
Simple molecular substances have very low boiling and melting points (oxygen: -183oC : -218oC) this because the forces of attraction between them are very weak and so very little energy is needed to overcome these forces
Can pure molecular compounds conduct electricity? why?
They cannot as their molecules are not charged
How do bonds within molecules compare to the forces between them?
Within molecules bonds are covalent and from electrostatic attraction between the nuclei and electrons and so are strong and don’t come apart. Between them however are weak forces of attraction that can be easily broken.
What makes up the Earth’s hydrosphere?
Oceans, lakes, seas and rivers, it is mainly water with some dissolved compounds: salts
How are crystals of ionic compounds arranged and how does this relate to their properties?
They are arranged in a regular lattice, held together by opposite forces of attraction between charged ions, they therefore have high melting and boiling points as lots of energy is required to break the ionic bonds in lattice
What happens when ionic compounds are dissolved in water and how does this affect their ability to conduct electricity?
Ionic compounds do not conduct electricity when solid because the ions aren’t free to move, when dissolved however they can move and do conduct.
What happens to some positive metals when an alkali is added to them?
They form a precipitate of an insoluble compound, the colour can be used to identify the ions in the compound
What are the colours of the precipitates of:CalciumCopperIron(II)Iron(III)Zinc?
Calcium: White precipitateCopper: Light blueIron(II): GreenIron(III): Red-brown (All insoluble in excess)Zinc: White (soluble in excess, giving a colourless solution)
What is added to negative chloride, bromide, iodide and sulfate ions to identify them?
Dilute silver nitrate or dilute barium chloride
What is added to negative carbonate ions to identify them?
Dilute acids and looking for fizzing
What makes up the Earths lithosphere?
The crust and the part of the mantle just below it, they are made up of a mixture of minerals.
How are diamond and graphite made and what are their corresponding properties?
They are made up of carbon atoms arranged in a regular pattern joined by covalent bonds and hence are very strong. These giant covalent structures have very high melting and boiling points and don’d dissolve in water.
How does the structure of diamond and graphite differ?
In diamond each atom is covalently bonded to 4 others in a 3-D tetrahedral lattice and so each is fixed firmly in place.However in graphite each layer is covalently bonded to each other and so each layer is strong but between each layer is only a weak force so the layers slide over each other.
Can graphite and diamond conduct electricity?
Graphite has free moving electrons between layers and so it can whereas in diamond none are free to move so it can’t.
