C1- Atomic structure and Periodic table (Compounds (Compound is 2 or more…
C1- Atomic structure and Periodic table
Atoms contain ; protons, neutrons and electrons with the nucleus containing the neutrons and protons. Protons : mass of 1 and charge of +1. Neutron : mass of 1 and charge of 0. Electron : mass of very small (0) and charge of -1.
Each atom has a layout of their symbol and two numbers ; the top number (largest) is the mass number and the bottom (small) is the atomic number.
Elements consist of atoms with the same atomic number. All the elements are represented within a symbol some are usual and can tell what it belongs to however some cannot eg. Na=Sodium, Fe=Iron and Pb=Lead.
There are also isotope of the elements which means they are exactly the same just with an extra neutron changing its mass.
Atomic mass (Ar) = Sum (isotope abundance x mass number) / Sum of abundance.
Compound is 2 or more elements which have chemically reacted / bonded which can be done by giving, taking or sharing electrons. Formula shows what atoms are contained within the compound.
Chemical equations show the chemical change taken place and can also be represented in their symbols this also helps balance out the equation.
Their are three types of bonding : Ionic bonding (metal and non-metal), Metallic bonding (metal and metal) and Covalent bonding (non-metal and non-metal).
Mixture and Chromatography
Mixture is easily separated as is not a compound and their are many methods to separate mixture, compounds aqueous solution such as ; Filtration, Crystallisation, Distillation, Fractional Distillation and Chromatography.
Filtration separates insoluble solids from liquids and Crystallisation and Evaporation separates soluble solids from solutions. Paper chromatography does this by separating the dyes within an ink, first a line is drawn at the bottom (with pencil) and a spot of ink is placed on the line then paper is placed in a solvent (either water or ethanol), then receive a chromatogram to collect the data.
Distillation separates solutions by turning one of the elements into vapour which is then cooled, condensed and collected separating them from the other element due to them all having very different boiling points. However if boiling points are close to one another we use a different technique called Fractional Distillation (mixture of oils such as ; crude oil)Lower boiling point to the highest.
History of atoms
John Dalton discovered that an atom was a solid sphere, then JJ Thomson discovered that there was another charge discovering electrons therefor came up with plum pudding model which means solid positive sphere with small electrons within. Rutherford then proved this theory wrong due to his testing with alpha particles and discovered atoms were almost all empty space. Bohr then discovered that the atoms have shells and further testing in they also found protons.
Electronic structure ; 2,8,8 and a full shell = 8
Development of Periodic table
Used to be arranged by atomic mass or their physical and chemical properties. Then Dimitri Mendeleev left gaps in his development of the table to predict new elements.
Modern Periodic table
There is an increase in atomic number and metals are to the left, non-metals to the right. The columns have all got similar properties to the other in the column, vertical columns are called groups and have same number of electrons on outer shell. Rows are called periods and this introduces a new shell from the last atom to the next.
Metals and non-metals
Metals form positive ions as lose the electron. Non-metals form negative ions as gain the electron.
Metallic bonds are strong and conduct electricity and heat but also have high melting and boiling points.
reactive, soft alkali metals, as go down the group there is an increase in reactivity and atomic mass but lower boiling and melting point.
Halogens are non-metals, all being coloured vapour ; fluorine (yellow), chlorine (green), bromine (brown/red), iodine (purple). As go down the group becomes less reactive but the atomic mass gets higher as well as the boiling and melting point.
Colourless inert gases, meaning doesn't react this is because all the elements contain a full outer shell of 8, which is why other atoms react with one another therefore they don't need to do so. As go down the group the boiling point increases as well as the number of electrons.