C1-Atomic structure and periodic table

• atoms contain protons neutrons and electrons
• atoms have a radius of 0.1 nanometres
• the nucleus is in the middle of the atom and contains protons and neutrons and has a positive charge
• the electrons move around the nucleus on shells they are negatively charged and tiny but cover a lot of space
• proton = mass 1 = charge +1
• neutron = mass 1 = charge 0
• electron = charge very small = charge -1
• number of protons equals the number of electrons
• atoms are neutral they have no overall charge this is because they have the same number of protons and electrons
• the charge on the electrons is the same size as the charge on the protons but opposite so they cancel each other out
• atomic number tells you how many protons ther are
• the mass number tells you the total number of protons and neutrons
• to get the number of neutrons just subtract the atomic number from the mass number

  A) protons and neutrons

  B) protons

  
• isotopes have the same number of protons but different number of neutrons
• relative atomic mass = sum of (isotopes abundance x isotope mass number) / sum of abundance of all the isotopes
• when elements react they form compounds
• mixtures are easily separated such as filtration, crystallisation and chromatography
• chromatography : to separate dyes in an ink. draw a line near the bottom of a sheet of filter paper in pencil. add a spot of the ink to the line and place the sheet in a beaker of solvent e.g water. the solvent used depends on what`s being tested. make sure the ink isn`t touching the solvent. place a lid on top of the container to stop the solvent from evaporating. the solvent seeps up the paper carrying the ink with it. watch different dyes in the ink will move up the paper at different rates.
• if any dyes are at still on the line they are insoluble
• filtration separates insoluble solids from liquids
• evaporation. pours the solution into an evaporating dish, slowly heat the solution and the solvent will evaporate and the solution will get more concentrated. eventually crystals will start to form. keep evaporating dish until all you have left are dry crystals
• crystallisation. pour the solution into an evaporating dish and gently heat the solution and some of the solvent will evaporate and the solution will get more concentrated. once some of the solvent has evaporated remove the dish from the heat and leave the solution to cool. the salt should start to form crystals as it becomes insoluble in the cold and highly concentrated. filter the crystals out of the solution and leave them in a warm place to dry
• filtration can be used to separate rock salt. firstly grind together to make mixture small. put mixture in water and stir. the sand will dissolve but the sand won`t. filter the mixture with filter paper. evaporate the water from the salt so that it forms dry crystals
• simple distillation is used to separate out solutions

  A) solution

  B) evaporates

  C) condenses

  D) pure water

  E) salt

  
• fractional distillation is used to separate a mixture of liquids

  A) fractional distillation

  B) fractionating column

  C) lowest boiling point

  D) higher boiling points

  E) condensing

  
• JOHN DALTON described atoms as solid spheres and said that different spheres are made up the different elements. JJ THOMSON said atoms weren`t solid spheres but his experiments the charge and mass showed that an atom must contain even smaller negatively charged particles (electrons) called the plum pudding model it shows a ball of positive charge with electrons stuck in it
• RUTHERFORD showed the plum pudding model was wrong and the alpha particle scattering experiments it proved that if the plum pudding model was correct the particles would pass through the sheet or be slightly deflected but whilst most particles did go straight through most would deflect more than expected and some backwards and came up with the nuclear model. it a tiny positively charged nucleus at the centre and a cloud of electrons surround the nucleus so the atom is empty space and when the alpha particles came near the positive charge of the nucleus they were deflected
• BOHRS nuclear model of atom suggested that all the electrons were contained in shells and proposed that electrons orbit the nucleus in fixed shells
• further experiments by RUTHERFORD showed that the nucleus can be divided into protons
• CHADWICK discovered neutrons and resulted in the model of an atom which was pretty close to the modern day known as the nuclear model
• noble gases have a full outer shell
• the periodic table was first arranged by atomic weight
• MENDELEEV re arranged the table by similar properties
• the recent periodic table is arranged by increasing atomic number and has 100 elemnets
• elements with similar properties form columns
• vertical columns are called groups
• the group number tells you how many electrons it has on the outer shell except group 0
• all metals have metalic bonding
• metals are strong but can be bent or hammered they are good at conducting heat and electricity and have high boiling and melting points
• non metals are dull looking brittle and aren`t always solid at room temp and don`t usually conduct electricity and often have a lower density