chemistry

• What are isotopes

  they have the same number of protons and electrons but different number of neutrons
• Ionic bonds

  is a strong electrostatic attraction between oppositely charged ions between non metal
• What is a Ionic lattice structure

  Is positively and negatively charged ions are arranged in a regular, repeating pattern held together by strong electrostatic forces
• Covalent bonds

  Is formed between two non metals
• Ionic compound

  consist of metal bonded to a non metal via electron transfer and form a giant ionic lattice
• Why does Ionic compound require a lot of energy to break

  Because they have strong covalent bonds and high melting and boiling point
• Simple covalent molecule

  consist of non metal bonded together via electron transfer
• Empirical formula of 45.4g of carbon,7.6 hydrogen and 40.3 of oxygen. Ar: of C= 12 of H=1 of O=16

  First: divide 45.4/12 and 7.6/1 and 40.3/16 Second: divide all the answer by the smallest number 3.78/2.52 and 7.6/2.52 and 2.52/2.52 Third: convert them to whole numbers and get C3H6O2
• Allotropes

  Different structural forms of the same element in the same physical state
• Fullerenes


  Are allotropes of carbon connected by single bonds and double bonds
• Alloys

  2 or more different element mixed together two different metals
• Limiting reactants

  Reactants that are all used up
• Rf value

  Distance travel by substance/Distance travelled by solvent
• How is waste water treated

  First passed through screening(the grating and mesh that removes large objects)Second (sewage is left to sink and all the heavy particles sit at the bottom called (sludge)) Third(air is pumped through effluent to supply the bacteria with oxygen)Fourth(The sludge is sealed in a container to prevent air from entering)
• How is fresh water treated

  First is passed through wire and mesh to filter out large object. Second is pass through gravel and sand to filter out rocks. Third used chlorine to kill any micro-organism
• How to Measure PH

  Universal indicator and PH probe(dip the probe in solution to tell the exact pH)
• What is the Ph for Acid and Alkaline

  Acid 1-7 Alkaline 7-14
• What is the difference between strong acid and weak acid

  Strong acid fully ionize and weak acid Partially ionized (reversible(equilibrium)
• Neutralizing reaction 1

  Metal+ Acid=Salt+water
• Neutralizing reaction 2


  Metal carbonate +acid=salt+water+carbon dioxide
• Neutralizing reaction

  Positive hydrogen ions react with negative hydroxide ions
• Soluble salt

  Acid + insoluble metal
• Oxidization


  When product is displaced
• reduced


  When a product is formed
• What happens at the cathode

  We look at the reactivity series to see which one gets discharged
• What happens at the anode


  If there is a group 7 present it will be discharged but no present then hydroxide will be discharge
• Reactivity series

  P otassium, S odium, L ithium, C alcium, M agnesium, C arbon, Z inc, I ron, H ydrogen, C opper
• What happens when you go down the reactivity series

  It gets less violent and less reactive
• Oxidation


  substance come in contact with oxygen
• Redox

  Is the process of reducing and oxidizing at the same time
• Displacement

  Where a more reactive metal displace the less reactive one
• under what conditions can equilibrium happen

  Can only happen in a closed system no products escaping
• Group 1 alkaline metals

  L ithium, S odium,P otassium,R ubiadium,C aesium,F rancium
• Group 1 alkaline properties

  more reactive when you gown down because its shell gets further apart from the nucleus so its easier to lose and melting point and boiling point decrease
• Halogens

  F lorine(yellow),C hlorine(green),B romine(red brown),I odine(grey)
• Halogen properties

  As you go down the reactivity decrease and the melting and boiling point increase as the nucleus gets further away from the shell making it harder to attract electrons
• Noble gas properties

  Colourless gas, not flammable,inert(full outer shell) eg:helium
• Rate of reaction

  Quantity of products form/products used (divide)time taken
• Catalyst

  a substance that increase the rate of reaction without being chemically used
• exothermic

  energy released to the surroundings, such as combustion and oxidisation