Monday, 11 February 2019

Reactivity of Group 7 elements

These elements are found in the same group as they have the same number of electrons in their outer shells.


They have similar properties as they all need one electron to get a full outer shell.

Trends:

Atomic Size – Increases down the group, as the atoms have more shells

Density – Increases down the group, as the atomic mass increases (more protons and neutrons).

Reactivity – Decreases down the group, as it is harder for the nucleus to attract an outer electron, as the outer shell is further from the nucleus and the inner shells shield the attractive force of the nucleus.

It is important to know the reactivity of the halogens with iron wool and with halide salt solutions in displacement reactions:




Reactivity of Group 1 metals



These elements are found in the same group as they have the same number of electrons in their outer shells.




They have similar properties as they all need to lose one electron to get a full outer shell.

Trends:

Atomic Size – Increases down the group, as the atoms have more shells

Density – Increases down the group, as the atomic mass increases (more protons and neutrons).

Reactivity – Increases down the group, as it is harder for the nucleus to attract the outer electron, as the outer shell is further from the nucleus and the inner shells shield the attractive force of the nucleus. So the outer electron is more easily lost


The Royal Society of Chemistry video below shows the reactivities of some of the Group 1 metals:



Thursday, 22 March 2018

Global Warming

This is a YouTube video showing the Scientific Eye programme on Global Warming, some useful ideas and explanations!


Limestone

Limestone is a sedimentary rock found in the earth.  It is formed from the shells of dead sea creatures which become crushed and buried at the bottom of the sea, when these creatures die.


Limestone is made up of the chemical calcium carbonate, CaCO3.  It is a metal carbonate. The following YouTube video is from the Scientific Eye series and explains the importance of limestone and the issues related to it.  You might be expected to discuss the social, economic and environmental of extracting and using limestone.



Limestone can undergo reactions as part of the 'Limestone cycle'.  The first step is a thermal decomposition, this is where a substance is broken down into smaller compounds using heat. The ease with which they decompose varies within a group. The higher up the reactivity series a metal is, the more stable its carbonate will be, so the least reactive metals have the carbonates that decompose most readily. Looking at group 2 magnesium carbonate decomposes relatively easily, calcium carbonate requires significant heating to decompose. As you go further down the group the metal carbonates become more stable and less easily decomposed by heat.





Calculating Reacting Masses 2

The earlier 'Calculating Reacting Masses' blog, talked about how you could use factors between the molecular masses of substances and their actual masses in order to find the mass of an unknown in a chemical reaction.  A more useful way of doing this is to look at the moles of substances in reactions, the following slideshow explains this, pause and repeat to get a better understanding. 

Look at the original 'Reacting Masses' blog post. Does the moles method give the same result as the worked example?



Wednesday, 8 November 2017

Rates of reaction revision

Some videos to help with revision of rates of reaction:

 
Where the following video talks about a fruitful collision it means a successful collision (one that has the energy to over come the activation energy).