Basic Information on Atoms

Atoms are very small particles which form the basic building blocks of everything around us.

The ‘magic numbers’ in chemistry are 2, 8, 8 which are the maximum numbers of electrons that can fit into the first, second and third shell.

Tip – When you draw the electrons on a dot and cross diagram try to draw them in pairs as it makes it easier for us to count how many electrons are in each shell. If you do not do this, then it becomes harder to know how many electrons you have drawn and you run the risk of miscounting the electrons and putting more electrons than you should be. (Electrons also move around in pairs, so by drawing them like this it makes the diagram more realistic).


We can work out how many electrons would be in the outer shell of a particular element by looking at the periodic table and by looking at the proton number. With atoms (not ions) the number of protons in the nucleus is always equal to number of electrons in that particular atom.

Lithium has a proton number of 3 so this means there are 3 protons in the nucleus and 3 electrons in the atom’s shells.

The element’s aim is to become stable during its life. An element becomes stable when its outer shell is full of electrons. (Elements want full outer shell, we need to keep this in mind when we draw our dot and cross diagrams).

Covalent molecules – A covalent molecule is when we have 2 non-metal atoms. We can tell if an element is a metal or non-metal by looking at the periodic table and which side it is on of the baron step.

If we need to draw a dot and cross diagram of CH4 we would need to think about the electron configurations (2, 8, 8) of the elements in that bond.

So carbon has 6 electrons (2 in its first shell and 4 in its outer shell, this means that it needs 8 electrons to have a full outer shell, so it will need 4 more electrons). A non-metal element would gain electrons by making a bond and each time the atom forms a bond it gets an additional electron. This means that carbon needs to make 4 bonds in order to get a complete outer shell. As carbon always will have 4 electrons it will always need to create 4 additional bonds. This means that we can determine how many bonds an element will need to make by simply looking at how many electrons that element needs in order to get a full outer shell.

atom 2

Tip – When drawing covalent bonds do not draw the electrons in pairs, instead draw them separately as these electrons will overlap the orbit of a different electron. When a carbon atom and a hydrogen atom stick together (bond together) their orbits will overlap and both of these atoms will share an electron. Hydrogen requires 2 electrons to be stable so it shares an electron with carbon. The formula CH4 has the number 4 because it needs to make 4 bonds to become stable.

Another example would be CO2 the carbon atom needs to make 4 bonds, but the oxygen only needs to create 2 as it has 6 electrons in its outer shell. Each carbon atom needs to make 4 bonds while oxygen needs to make 2 bonds. We would be making a double if two oxygen atoms bond together. In a single bond each element shares a single electron. In a double bond each element shares 2 electrons.
The electrons that do not overlap in a covalent bond are known as ‘unbonded pairs’ or ‘lone pairs’.

Ionic bonds – An ionic bond is when a non-metal atom bonds with a metal atom. Remember – Always a non-metal atom will take electrons from a metal atom. For example NaCl – a chlorine atom will take an electron from the sodium atom so they will both have a full outer shell, which means they are stable.

An electron has a charge of -1 so if a chlorine atom gains an electron it becomes negatively charged. If the sodium atom loses an electron it becomes positively charged.
Another example would be MgO. A magnesium atom needs to lose 2 electrons to become stable while oxygen needs to gain 2 electrons to become stable.

An interesting fact to finish off with… Did you know there are more atoms in a single glass of water than all the glasses of water from the whole of the Earth’s oceans.

Thank you for reading.

What is a Maillard Reaction?

The Maillard reaction is a type of ‘nonenzymatic browning’ which is slightly similar to ‘caramelisation’. The Maillard reaction often results due to a chemical reaction between the amino acid and a reducing quantity of sugar (this usually requires heat).

The Maillard reaction is extremely important in the preparation, presentation or the baking of many and various different types of food. This type of reaction was named after a famous chemist known as Louis Camille Maillard, who first described this in 1912 while he was attempting to reproduce biological ‘protein synthesis’.
The type of amino acid is vitally important as it will often determine the flavour as a result. This reaction forms the basis of the flavouring industry.

In the process, hundreds of different flavour compounds are produced. These compounds, in turn, break down to form even more new flavour compounds, and this will continue. Each type of food has a rather distinctive and particular group of flavours compounds that are formed during the Maillard reaction.

Boiling food in water does not tend to allow the reaction to take place, as the boiling point of water (100 degrees Celsius) in far to low to set off the reaction. Frying foods in vegetable oils will often reach temperatures ranging from 180 degrees Celsius to 210 degrees Celsius, providing these temperatures are maintained the reaction will occur.

The brown crust of bread and the appetising crisp outside of chips are all the result of the Maillard Reaction.

Thank you for reading.

What are E-Numbers? – Read on to find out…

The name that is given to any additive, preservative or an emulsion used in the production and preparation of food is the ‘E-Number’. This shows that this ‘product’ has been for use in Europe and the USA (but not necessarily in all countries).

Types of additives and preservatives:

1) E 100 – Food colours (Example – E 102 – Tartrazine)

2) E 200 – Preservatives (Example – E 211 – Sodium Benzoate)

3) E 300 – Antioxidants 9 (Example – E 300 – Ascorbic Acid)

4) E 400 – Emulsifiers, Gelling Agents, Thickeners (Example – E 404 – Calcium Alginate)

5) E 900 – Sweeteners (Example – E 951 – Aspartame)

6) Others – Acidity Regulators, Bulking Agents and Flavour Enhances (Example – E 621 MSG)

E-Numbers that are Advisable for Children to Avoid –

Some of the E numbers that the UK government have suggested that children should avoid, especially if they have shown any signs of suffering from hyperactivity, these include:

1) E 102 – tartrazine. As well as hyperactivity, this has been linked to asthma, stomach problems, tiredness and skin irritation. This is commonly found in food such as biscuits, sweets and interestingly mushy peas.

2) E 110 – sunset yellow. In addition to behavioural problems and hyperactivity, it has also been linked allergies and gastric problems. It has been found in foods such as in ice creams, soft drinks and sweets.

3) E 112 – carmoisine. This has also been linked to an increase in allergies and intolerances. This product is commonly used in biscuits, jelly, ready meals and sweets.

4) E 124 – ponceau 4R. This has been linked to instances of allergies and intolerances. This product can be found in biscuits, drinks and sweets.

5) E 129 – allure red. This has been linked with asthma, difficulties in digesting food, gastric upset, stomach aches and even vomiting. This product can be commonly found in foods such as sausages and soft drinks.

6) E104 – quinoline yellow. It has also been linked with issues of asthma and skin irritation. It has been found in products such as smoked meats (including fish), pickles, fizzy drinks, biscuits, chocolate and sweets.

7) E 211 – Sodium benzoate. This product has been linked to asthma, breathing difficulties, head aches and also hyperactivity. This product is often found in foods such as baked foods (cakes and pastries), ice lollies, ice creams and fizzy drinks.

I hope this gives you a better idea on what are E numbers when used in food and which ones should be avoided.

Thank you for reading.