Volumetric Analysis Made Easy
What is the basic structure?
The basic structure of an atom consists many things. The three main things which makes up an atom are: Electron, Proton and an Outer shell for the electrons to orbit around
Name of the element
Symbol of the element
Relative atomic mass
How are electrons arranged in shells?
Electrons are variously arranged in the periodic table by their properties. Elements which have the same properties are arranged in the same group and elements which have the same number of outer shells are arranged in periods.
Groups: All groups which are in the periodic table are horizontal and all the elements have similar chemical properties. E.g. (group 1 have similar properties and all have one electron in their outer shell)
Periods: All periods which are in the periodic table are vertical and all the elements have the same amount of shells. E.g. (first row of elements will all have one outer shell)
Here are the first 20 electron orbital arrangement of the first 20 elements.
Here is a picture of what the periodic table:
Structure of the periodic table.
The periodic table is where elements are arranged based on their atomic number and electron configuration in groups and periods. Also, the periodic table determines whether the element is a metal of a non-metal. In the periodic table metals are generally found on the right-hand side and non-metals are generally found on the left-hand side. However, there also metals called ‘transition’ metals. Transition metals are usually found in the middle of the periodic table which are in between group 2 and 3. The transition metals are normally hard and dense. Also, there are groups and periods in the periodic table. Groups are horizontal and are also known as columns. Furthermore, each group determines the similarities of each chemical, and each period determines how many shells the element will have.
5 different elements and their groups/ period
1. Helium: Helium is in in group 0,8 which is also known as the ‘noble gases. Helium is found on the right-hand side of periodic table. Group 8,0 are unreactive because all the elements have a full outer shell. The orbit configuration of helium is ‘2’. The symbol for helium is (He), and helium is in row one so therefore it has one outer shell
2. Lithium: Lithium is in group 1 and its an alkali metal. Also, lithium has one electron on the outer hell which determines that its in group 1. Furthermore, as you go down group 1 the amount of electron shells increases by one. The symbol for Lithium is (Li), and lithium is in row 2 therefore it has 2 shells.
3. Bromine: Bromine is in group 7 which is also known as ‘halogens. Group 7 elements are all diatomic (they always come in 2) e.g. Fluorine: F2, Bromine: Br2 etc. Also, the further you go down group 7 the boiling point will increase, and the elements will be less reactive. Lastly, bromine is in row 4 so it has 4 shells.
4. Magnesium: Magnesium is in group 2 which is an alkaline metal which have low melting points and high boiling points. All group 2 metals have 2 electrons in their outer shell, and because magnesium is in row 3 it has 3 shells.
5. Nickel: Nickel and all other metals are transition. Transition metals are between group 2 and 3. Also, all transition metals including nickel are ductile, malleable and are good conductors of heat.
What happens when the first ionisation energy of the element changes when you across a period and cross a group?
The first ionisation energy will increase when going across a period. This is because when you across a period more protons are being created/ added to the nucleus of the atom. This will increase the amount of charge the nucleus has. Therefore, the energy levels will be hard to remove because it will be tightly held. However, the first ionisation will increase but when the atomic radius decreases it will then become harder to remove the electron because the electron will have a weaker attraction towards the positive charge of the nucleus.
Why does the atomic radii of the element changes as you cross a period and descend a group?
The atomic radii of the element will change when you cross a period and descend a group because of the increase of the number of protons and electrons across the period. Also, as the electron are attracted towards the nucleus the radius will be smaller than usual.
What is ionic bonding?
Ionic bonding is the process when a metal and non-metal react together. By doing this the metal will lose one or more electron to form a positive (+) charged ion. However, the non-metal atoms will gain the electron to form negatively charged ion. The ions are strongly held together by electrostatic forces. This is called ionic bonding.
As you can see in the diagram the sodium (Na) atom loses its outer electron. This will then from an Na+ (sodium) ion. However, the chlorine (Cl) atom gains the electron. This will then form an Cl- (chlorine) ion. This is called ionic bonding.
What is covalent bonding?
Covalent bonding is when non-metal atoms bond together. Covalent bonds are held by electrostatic forces which are strong. Also, each atom will make enough covalent bonds to fill up its outer shell by doing this it will make them very stable.
As you can see in the diagram there are 3 ways to draw a covalent bond. The first way is the dot and cross diagram. The dot and cross diagram are shown through the overlap between the 2 shared electrons. Also dot and cross diagrams shows which atoms in the electrons in a covalent bond form. The second way to draw a covalent bond is drawing the displayed formula. The use of the displayed formula shows the covalent bond as single lines. However, if there were two lines it will show you that there is a double covalent bond. Also, they show you how the atoms are connected in large molecules. Lastly, the other way to draw a covalent bond is to draw a 3D model. The use of the 3D model shows you the atoms and how they are arranged.
How are metals formed?
Metals are formed when two or more elements react together. Also, metal can easily react with other elements and when atoms give up their electrons to form positive (+) ions and compounds.
As you can see in the diagram there is a 3D representation of CH4 and a displayed formula which also represents the CH4 atom.
Experiment to make sodium carbonate:
Firstly, you must use evaporation
1. Slowly heat the solution in an evaporation dish so the solvent will evaporate
2. When doing the crystals will begin to form
3. Keep heating until all you have left are dry crystals
After doing this you will have to use crystallisation
4. Gently heat the solution in an evaporation dish
5. Once the solvent begins to disappear you will see crystals being formed
6. Leave the solution to cool
7. The salt should then start to form crystals
8. Filter the crystals out of the solution
9. Leave them in a warm place to dry
Experiment on titration
1. Use a pipette and pipette filter to add 25cm3 of alkali to a clean conical flask
2. Add a few drops of indicator and put the conical flask on a white tile
3. Fill the burette with acid and note the starting volume
4. Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix
5. Stop adding the acid when the end-point is reached
6. Repeat step 1 to 5