Section 2: Chemistry of the elements Flashcards
What is a group in the Periodic table?
A column
What is a period in the Periodic table?
A row
Where are the metals and non-metals in the Periodic table?
Metals on the left, transition metals in the middle, non-metals to the right of staircase under boron.
How is a substance classified as a metal?
They conduct electricity and heat, and form alkaline metal oxides.
How is a substance classified as a non-metal?
They do not conduct, and form acidic non-metal oxides.
Why do elements in the same group have similar chemical properties?
Elements in the same group have the same number of electrons in their outer shells. This means they will behave in a similar way, and will react and bond similarly.
What are the noble gases?
They are a family of inert gases.
Why are the noble gases inert?
They are stable because they have a full outer shell, so they do not need to lose or gain electrons.
Describe the reactions of the group 1 elements with water.
They all react to produce a metal hydroxide and hydrogen.
Lithium - fizzing
Sodium - floats, makes small ball, melts, lots of fizzing
Potassium - produces lilac flame, spits around
Describe and explain the relative reactivities of the elements in Group 1.
The reactivity increases as you go down the group because there is more distance between the electron and the nucleus, making it easier for the electron to be lost.
What is the colour and physical state of chlorine?
green, gas
What is the colour and physical state of bromine?
brown, liquid
What is the colour and physical state of iodine?
grey, purple vapour, solid
What is the difference between hydrogen chloride and hydrochloric acid?
Hydrogen chloride is a gas, hydrochloric acid is the substance formed when hydrogen chloride is dissolved in water.
Why is hydrogen chloride acidic in water but not in methylbenzene?
An acid is a substance which dissociates hydrogen ions when dissolved in water. This happens in water, but not in methylbenzene, because methylbenzene is not a polar molecule.
Describe the relative reactivities of the elements in Group 7.
The reactivity goes down as you go down the group.
Describe experiments to demonstrate that a more reactive halogen will displace a less reactive halogen from a solution of one of its salts.
Using chlorine and potassium bromide:
If you add chlorine to potassium bromide solution, the solution will turn orange as bromine is formed. The more reactive chlorine has displaced the less reactive bromine from potassium bromide.
What happens in terms of reduction and oxidation in a displacement reaction?
A displacement reaction is a redox reaction. In the reaction between chlorine and potassium bromide, the potassium ions are spectator ions, and the bromide ions lose electrons, which are gained by the chlorine atoms.
What gases are present in air, and what is their approximate percentage by volume?
Nitrogen - 78%
Oxygen - 21%
Argon - 0.9%
Carbon dioxide - 0.04%
Explain how experiments involving the reactions of elements such as copper, iron and phosphorous with air can be used to investigate the percentage by volume of oxygen in air.
Copper, iron and phosphorus all react with air. If you know the volume of air that you have, then react it with on of these, then measure the volume of air afterwards; what has been lost is all oxygen that reacted.
How do you make oxygen in a lab?
The catalytic decomposition of hydrogen peroxide using manganese oxide as the catalyst.
2H2O2 (aq) –> 2H2O (l) + O2 (g)
How is carbon dioxide made by the thermal decomposition of metal carbonates?
When metal carbonates are heated they become carbon dioxide and a metal.
e.g. copper carbonate –> copper oxide + carbon dioxide
CuCO3 –> CuO + CO2