C4 - The Periodic Table Flashcards
How is an ionic bond formed?
When a metal reacts with a non-metal, ions are transferred from the metal atoms to the non-metal atoms. As a result, there will be positively charged metal ions and negatively charged non-metal ions.
Because the ions are oppositely charged, there is a strong force of attraction between them - forming an ionic compound.
How is a covalent bond formed?
Covalent bonds are formed between non-metal atoms that share electrons.
What is the charge and mass of an electron?
Charge: -1
Mass: 0
What is the charge and mass of a proton?
Charge: 1
Mass: 1
What is the charge and mass of a neutron?
Charge: 0
Mass: 1
What is an isotope?
A variety of an element with a different atomic mass but same atomic number.
Why do metal atoms usually form positive ions?
Metal atoms form positive ions because they lose electrons in their outer shell in an attempt to become more stable.
Why do non-metal atoms usually form negative ions?
Non-metal atoms form negative ions because their outer shells gain electrons in an attempt to become more stable.
Why does Sodium Chloride have a high melting point?
Sodium chloride has a high melting point because of the strong attractions between oppositely charged ions in a giant ionic structure.
It takes a lot of energy to overcome these attractive forces, meaning sodium chloride has a high melting point.
Why does Magnesium Oxide (MgO) have a higher melting point that Sodium Chloride?
MgO has a higher melting point that NaCl because it is made up of Mg2+ and O2- ions, as opposed to being made up of Na+ and Cl- ions.
The fact that the ions in MgO have double the charge means that the attraction between them is harder to overcome.
Furthermore, the O2- ions are smaller than the Cl- ions, meaning that the ions in MgO can be packed together more closely. This makes the forces of attraction harder to overcome.
Why do molten and dissolved NaCl conduct electricity whilst solid NaCl cannot?
When NaCl melts or dissolves, the ions are free to move and therefore they’ll be able to conduct electricity.
What is a giant ionic structure?
A large structure of positive and negative ions that are strongly attracted to eachother.
Why do carbon dioxide and water have low melting and boiling points?
They are simple molecular structures. While they have very strong covalent bonds between the atoms, the intermolecular forces between the molecules are relatively weak. As a result, the molecules can be easily parted.
Therefore, less energy is needed to separate them (boil or melt)>
Why are alkali metals stored in oil?
They react vigorously with water, meaning they have to avoid contact with it to prevent safety hazards. Oil acts a barrier between the alkali metal and the water.
What is the flame test colour for lithium?
Red
What is the flame test colour for sodium?
Yellow/orange
What is the flame test colour for potassium?
Lilac
What is the general word equation for the reaction of an alkali metal with water?
Alkali metal + water —> Hydroxide + Hydrogen gas
What is the symbol equation for the reaction between sodium and water?
Na + H2O —> NaOH + H2
it then needs to be balanced
Why do alkali metals all have similar properties (low melting point, low density, very soft)?
They are all to keen to lose an electron and form positive ions with stable electronic structures.
Why do alkali metals become reactive as you go down the periodic table?
As you go down group 1, alkali metals become more reactive because the outer electron is more easily lost - this is because its outer shell is further from the nucleus (larger atomic radius), so less energy is needed to remove it.
What is oxidation?
Loss of electrons.
How might you setup a flame test to identify alkali metals?
- Dip a wire loop into some hydrochloric acid to clean and moisten it.
- Put the loop into a powdered sample of the compound to be tested, and then place in the end in a blue Bunsen flame.
- Flame will change colour depending on which alkali metal is present.
What is the physical appearance of chlorine at room temperature?
It’s a green gas.
What is the physical appearance of bromine at room temperature?
Bromine is an orange liquid.
What is the physical appearance of iodine at room temperature?
It’s a grey solid.
How do the properties of halogens change as we move down group 7?
- Their melting and boiling points increase
- They become less reactive
Why do halogens become less reactive as we move down group 7?
The further down group 7 a halogen is, the larger its atomic radius and therefore the less inclination there is to gain an extra electron.
What is the general word equation for a reaction between an alkali metal and a halogen?
Alkali metal + halogen –> salt
What is the balanced symbol equation for the reaction between sodium and chlorine?
2Na + Cl2 —> 2NaCl
What is a metal halide?
A salt formed from the reaction between a group 1 alkali metal and a group 7 halogen.
Will bromine react with sodium astitide? Explain your answer.
Yes, because bromine is more reactive than astatine, meaning that it will displace the astatine to form sodium bromide.
What is the symbol equation for the displacement reaction between chlorine and potassium iodide.
Cl2 +2KI –>2KCl + I2
What is the ionic equation for the creation of a halide ion from a chlorine molecule?
Cl2 + 2e- —> 2Cl-
What is a precipitation reaction?
A reaction between solutions that produces an insoluble solid.
Usually, what colour are copper compounds?
Blue
Usually, what colour are iron (II) compounds?
Light green
Usually, what colour are iron (III) compounds?
Orange/Brown
What is the general word equation for the thermal decomposition of a transition metal carbonate?
Carbonate —> metal oxide + carbon dioxide
What colour is copper (II) hydroxide (a precipitate)?
Blue
What colour is iron (II) hydroxide (a precipitate)?
Grey/green
What colour is iron (III) hydroxide (a precipitate)?
Orange/brown
What is the general word equation for a precipitation reaction between a transition metal and sodium hydroxide?
Metal sulfate + sodium hydroxide –> metal hydroxide + sodium sulphate
What is metallic bonding?
A strong attraction between a sea of delocalised electrons and closely packed positive ions.
Why do metals have high boiling points and high melting points?
Metals have high boiling points because of the strong metallic bonds present as a result of the strong attractions between positive ions and the sea of delocalised electrons.
Lots of energy is required to overcome this metallic bonding.
Why do metals conduct electricity?
They have a sea of delocalised electrons that is capable of carrying the electrical current.
What is a superconductor?
An extremely cold metal with zero resistance, meaning no electrical current is turned into heat (none is wasted). In theory, this means a current can continue flowing forever without ever dropping in size.
List potential uses/benefits of superconductors:
- Transmission of power without waste
- Super-fast electronic circuits
- Powerful electromagnets
Explain the drawbacks of super conductors.
- It is extremely hard and expensive to get metals down to the extremely low temperatures required for superconductivity.
How can we test for sulfate ions?
Barium chloride can be used to test for sulfate ions. If sulfate ions are present, a white precipitate will form.
How can we test for chloride ions?
In a silver nitrate solution, a white precipitate will be produced.
How can we test for bromide ions?
In a silver nitrate solution, a cream precipitate will be produced.
How can we test for iodide ions?
In a silver nitrate solution, a pale yellow precipitate will be produced.
Why can nitrates be found in our drinking water?
Fertilisers may ‘run-off’ into lakes and rivers.
Why might lead compounds be found in our drinking water?
Lead compounds get into drinking water via old lead pipes carrying it.
Why might we find pesticides into our drinking water?
Farmers might spray pesticides too near rivers or lakes.
What are the key stages in the water purification process?
- Wire mesh and gravel used to filter water.
- Iron sulfate used to make fine particles lump together and settle at bottom.
- Chlorine gas bubbled through water to kill harmful bacteria.
Why do some harmful substances remain in the water despite the purification process?
Some chemicals are dissolved in the water and can’t be removed - since filtration won’t work.
What is the main disadvantage of distilling sea water to produce drinkable water?
- It requires lots of energy to boil the water, meaning it is really expensive and certainly not practical to produce large quantities of sea water.
What is the general word equation for the precipitation reaction between barium ions and sulfate ions?
Barium ions + sulfate ions –> barium sulfate
What is the word equation for the precipitation reaction between silver nitrate and sodium chloride?
silver nitrate + sodium chloride –> silver chloride + sodium nitrate
What is the general word equation for the reaction between a metal sulfate and sodium hydroxide?
Metal sulfate + sodium hydroxide –> Metal hydroxide + Sodium Sulfate
