Gemma Stokes Unit 1 P1
The Periodic Table
Introduction
The History of the periodic table reflects over a century of growth in trying to understand chemical properties in the early 19th century,scientists first began to find ways to classify the elements.One of the first attempts to classify the elemts was carried out by a German Chemist called Johann Dobereiner in 1817.This chemist Johann Dobereiner realised that the properties of calcium,barium and strontium are actually very similar.Dobereiner also then began to notice that the atomic mass of strontium was in the middle between those of calcium and barium.After making this discovery he then decided to group these three elements into what was called a triad.
Later on Dobereiner also discovered several other similar groups of three elements which had similar properties.In each of these cases it was also noticed that the middle element has an atomic mass,which is halfway between the first anf the third elements in the Triad.However John Doberereiners ideas were not taken seriously by any other people.
The peridoic table itself is actually a visual representation of the periodic law,This law states that certian properties of the elements are repeated periodically,once they have been arranged by their atomic mass number.The elements in the table are arranged into vertical columns (groups) and rows (horizontally).
Below is a recent picture of the modern Periodic Table:
Atomic Structure
Atoms are particles of elements.They are made up of three types of particles these are: Electrons ,Protons ,Neutrons .Each of these particles which atoms are made up of each have different properties.Electrons are very tiny and very light and they have a negative electrical charge (-).Where as Protons are larger and and a lot heavier and they have the opposite charge to what a proton has.Neutrons are large similar to protons and they are also havy similar to protons.But Neutrons do not have any electrical charge.
Atoms are the most smallest particles found in ordinary substances,and these can usully join together to to form molecules.Hydrogen has the smallest atoms,which is made up of 1 single proton and a single electron orbiting it.An atom of Hydrogen has 1 proton,no neutrons and 1 electron.It has a zero charge because it has the same number of electrons and protons.
Isotopes
Each of the elements has its own atomic number.Therefore this means that all the atoms of any specific element must have the same number or protons and electrons.Therefore this means that any atom of Hydrogen ...
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Atoms are the most smallest particles found in ordinary substances,and these can usully join together to to form molecules.Hydrogen has the smallest atoms,which is made up of 1 single proton and a single electron orbiting it.An atom of Hydrogen has 1 proton,no neutrons and 1 electron.It has a zero charge because it has the same number of electrons and protons.
Isotopes
Each of the elements has its own atomic number.Therefore this means that all the atoms of any specific element must have the same number or protons and electrons.Therefore this means that any atom of Hydrogen has one proton,otherwise it wouldn't be a Hydrogen,and if the atom has two protons then it is helium.There are actually three typess of Hydrogen atom,each of these contain different number of neutrons.These are called isotopes of Hydrogen.
If you are refering about a certain isotope then you write it like as follows: This means X is the chemical symbol for the element,Z is the atomic number and A is the number of neutrons and protons both combined,this is called the mass number.
Relative Atomic Mass
The relative atomic mass is the relative mass of the isotope,scaled with carbon-12.Relative atomic mass of a chemical element basically just gives us an idea of how heavy it feels.If more than one isotope of the element is present, then the relative atomic mass is calculated by taking an average that takes account of the relative proportions of each isotope, however this means that the results won't result in being a whole number.
Chemical Bonding
Chemical bonding is the process in which atoms or molecules bond together,to form a new material.There are various types of chemical bonding.Heat and catalysts are usually needed to start the chemical bonding porcess off.Atoms can react with each other to form new substances these are called compounds.These are formed when two or more atoms chemically bond together.
Ionic Bonding
Ionic bonding occurs occurs between metals and non-metals.During the Ionic bonding process,the metal gives out it's outer electrons to the non-metal-the electrons are transfered using this type of bonding.Then the metal loses it's electrons,so its now a positive ion.Therefore this means that the non-metal has gained electrons,and it is now a negative ion.Because these ions have opposite charges they will attract to each other,and this attraction is then called a ionic bond.This means that both the metal and non-metal now both have full outer shells of electrons.
Below is an example:
Hydrogen Bonding
The Hydrogen bond is the attractive force between the hydrogen which is attatched to an electronegative atom of one molecule and a electronegative atom of a different molecule.If theHydrogen is close enough to another oxygen,fluorine or nitrogen in another molecule,then this means that there is a force of attraction which is called a dipole interaction.This specific bond "hydrogen bond" can have about 5% upto 10% of the strenght than a covalent bond has.Hydrogen bonding is vitaly important effect on the properties of water and ice.This type of bonding is also very important in proteins and nucleic acids and it is therefore in life processes.The unziping of DNA is the breaking of the hydrogen bonds which are used to help hold the two strands of the double helix together.
Compounds
Compounds are basically two or more elements which have chemically reacted to form different substances.Carbon dioxide is formed from a chemical reaction between carbon and oxygen.The newly formed compounds have all got very different properties compared to those of the individual elements.However unlike Elements compounds can be split into their constituent parts for example sodium chloride.
When compounds are split up into their simpler elements this process is called decomposition.The most commonly used ways of decomposing a compound is to use heat or to pass an electrical current through it.Every single compound has its own individual formula,this formula shows the elements that the compound is made up from.
Mixtures
when elements are put together they don't always form a compound all of the time.They only mix but they do not form a new substance.Therefore this means that they keep the properties of the individual elements.
Covalent Bonding
This type of bonding "covalent bonding" occurs between two elements with a small difference in their electro negativities (usually only non-metalics).The outer electrons are shared between two elements enabling both of them to have a full outer shell.
Hydrogen gas forms the most simplest covalent bond in the diatomic hydoren molecule.The Halogens such as chlorine also exist as diatomic gases by forming covalent bonds.The nitrogen and oxygen which makes up the bulk of the atmosphere also exhibits covalent bonding in forming diatomic molecules.
Metallic Bonds
The properties of metals suggests that their atoms possess strong bonds,however the ease of conduction of heat and electricity suggests that electrons are able to move freely in all different directions in a metal.
D1-Explain the use of standard solutions and how titrations would be carried out in industry
The term standard solution is a chemical term used to describe a solution of a known concentration.To standardize a quantity of a solution of acid you have to titrate is against a solution of alkali of known concentration.Then once you have calcualted this you can then use it in turn of a standard solution,to find the concentration of a solution of a alkali.Industry standards are often purchased rather than made.
Titration is carried out in many different ways in different industries,in hospitals titration is carried out by hand,as this may be more accurate however there is a problem with this because of the cause of human error.In many of the other industries titration is usually automated,therefore eliminating the problem of human error,because the awnsers would be accurate as they would be digital and would not bjust be guessed,However even though the awnsers would be accurate there could still be a risk of a systematic error occuring,But this method is a lot quicker to carry out rather than titrating by hand,where accuracy is the most vital part.This type of titration (automated) is also used in industries for titrating large quantities of volumes.Industries may also measure the endpoint in a different way,as sometimes they may use a Ph indicator,a potentiometer,or they may use a PH meter.The winemaker industry tend not to use old manual titrations,colour indicators,time consuming aeration oxidation tests,and dilution calculations and they are now using more reliable and faster titratiion methods.In this particular industry it is vitally important that the instrurments deliver the information qucikly,inexpensively and also the results need to be a high accuracy.