Periodic Table Flashcards
What is meant by the terms group and period?
Group: vertical columns
Periods: Horizontal rows
Explain the classification of elements as metals or non-metals
Metals: solids with high melting and boiling points, relatively high densities. Are shiny when polished, good conductors of electricity and heat, form positive ions in their compounds, have oxides reacting with acids to give salt and water.
Non-meatls: low melting and boiling points, don’t usually conduct electricity, poor conductors of heat, form negative ions and covalent compounds.
Why do elements in the same group of the Periodic Table have similar chemical properties?
They have the same number of electrons in their outer shells
What are the properties of noble gases?
They are all monatomic. Their densities increases as the atoms get heavier, their boiling points also increase as you go down the group because the attractions between one molecule and its neighbours get stronger as the atoms get bigger. More energy is needed to break the stronger attractions.
Describe the relative reactivities of the elements in Group 1
Melting and boiling points are very low for metals and get lower as you go down the group. Their densities tend to increases but not as tidily as the noble gases and they are softer as you go down.
Describe the reactions of lithium, sodium and potassium with water
Lithium: slower than sodium. Lithiums melting point is higher than sodiums and the heat isn’t produced as quickly so the lithium doesn’t melt.
Sodium: floats because it is less dense. It melts because its melting point is low and a lot of heat is produced by the reaction. A white trail of sodium hydroxide is formed which dissolved to make a strongly alkaline solution.
Potassium: faster than sodium and enough heat is produced to ignite the hydrogen which burns with a lilac flame. Potassium spits around.
Explain the relative reactivities of the elements in Group 1 in terms of distance between the outer electrons and the nucleus
The bigger the atom, the more easily the outer electron is lost as the effect of the force of attraction falls very quickly as distance increases. The closer the outer electron is to the nucleus, the less reactive it is as there is a stronger force of attraction.
What are the colours and physical states of chlorine, bromine and iodine at room temperature?
Chlorine: gas - green
Bromine: liquid - dark red liquid / brown vapour
Iodine: solid - dark grey solid / purple vapour
What is the difference between hydrogen chloride gas and hydrochloric acid?
Hydrogen chloride is a colourless gas at room temperature. It dissolved in water and it’s ions dissociate into H+ and CL- which makes it acidic, turning it into hydrochloric acid.
Why is hydrogen chloride is acidic in water but not in methylbenzene?
Hydrochloric acid is acidic in water because the ions dissociate into H+ and CL- this makes it acidic due to the H+ ion. The hydrochloric acid is not acidic in methylbenzene because the ions don’t dissociate.
describe the relative reactivities of the elements in Group 7
Are diatomic molecules, go from gases to liquids to solids as you go down the group. Become less reactive towards the bottom of the group, are oxidising agents with oxidising ability decreasing as you go down the group and will displace elements lower down the group from their salts.
Describe halogen displacement reactions
Chlorine with potassium bromide:
If you add chlorine solution to colourless potassium bromide solution, the solution becomes orange as bromide is formed. The more reactive chlorine has displaced the less reactive bromine from potassium bromide forming potassium chloride.
Chlorine with potassium iodide:
Adding chlorine solution to potassium iodide solution gives a dark reddish-brown solution of iodine. If an excess of chlorine is used, a dark grey precipitate of iodine is formed.
Chlorine is an oxidising agent, potassium ions are spectator ions.
What is a redox reaction?
A reaction in which both reduction and oxidation are occurring
