Year 11 Chemistry

Year 11 Chemistry

1. Atoms

   • Atoms are made up of protons, neutron and electrons. Neutrons have no charge, protons has a positive charge and electrons have a negative charge
     • The protons and neutrons sit in the center of the atom which is the nucleus. The electrons are located on valence shells outside the atom. The first valence shell can hold two electrons and the rest can hold eight
     • To make the atom/element balenced the atom loses or gains electrons to create a full valence shell. If it gains electrons then the atom will have a negative charge as it has more electrons that protons, if the atom loses electrons the atom will then have a positive charge as there are more protons than electrons
     • The atomic number is the amount of protons and electrons are in the atom, to find out the number of neutrons there are in the atom you minus the mass and atomic number
   • Isotopes
     • Isotopes are atoms of the same element, they have the same number of protons but with a different numbers of neutrons
   • Ions
     • An ion is an atom that has lost or gained an electron to create a full valence shell
     • If it loses an electron the atom becomes positive - charged
     • If it gains an electron then it will become negative - charge
     • Ionic Compounds
       • Iconic compounds from when positive ions attract and bind to negative ions in ratio that give a neutral overall charge
       • E.G: Na+ attracts to Cl - because they both lost or gained one it will make NaCl, sodium Chloride
       • E.G: Ca2+ = OH- OH- which makes Ca(OH)2 because you needed two OH- to balence the two positive calciums, making Clacium Hydroxide
       • Al3+ Al3+ = O2- O2- O2- which forms Al2 O3 Aluminium oxide

2. Chemical reaction

   • In a chemical reaction, exsisting substances (reactants) interact with each other and are changed into new substances (products)
   • For a reaction to occur reactant particles must collide with one another
   • Particles must collide with energy to break the bonds within particles, the particles must collide from the correct orientation for new bonds to be formed
   • Effect of collisions result in the formation of new products (substances)
   • Rate of reaction
     • Reaction rate is the speed at which the chemical reaction occurs
     • Reaction rate can vary between different experiments but is measured in the time it takes for a new product to be made
     • Affects on rate of reaction
       • The rate of reaction could be increased by: Surface area, increasing the surface area of a solid reactant, smaller pieces of reactant expose more reactant particles, so greater number of effective collisions occur.
         • Increasing the concerntration of a reactant, more reactant particles will exist in a given volume and so greater number of effective collisions
         • Increasing tempreature, reactant particles move faster (more kenitic energy) and so a greater number of effective collisions occur.

3. Writing Chemical equations

4. Acids and Bases

   • Acids
     • Acids are substances that form acidic solutions when dissolved in water
       • Acid releases hydrogen ions when dissolved in water, the hydrogen ions is what makes the resulting solution acidic
     • Strong acids: release high concerntrations of acid, Weak acids: release low concerntrations of hydrogen ions
     • strong acids are corrosive and eat away at materials through chemical reaction, weak acids have a sour taste and can leave skin irritation
   • Bases
     • Bases are substances that neutralise acidic solution
     • Soluble bases, alkalis release hydroxide ions when dissolved in water, these hydroxide ions that make the resulting solution alkaline
     • Strong bases: high concerntration of hydroxide ions, weak bases: low concerntrations of hydroxide ions
     • strong bases are caustic and they eat away materials by chemical action, weak bases have a bitter taste and a slippery feel
   • PH scale
     • Red litmus paper stays red if acidic or turns blue if an alkailine, blue litmus paper stays blue if it is an alkaline and turns red if acidic
     • Universal indicator is used to get the best reading of what the solution is. the liquid will turn red if acidic the less red the weaker, blue if alkaline the more purple the weaker and green if neutral.
   • Neutralisation
     • Neutralisation is a reaction in which an acid reacts with a base resulting in a reduction in acidity or alkalinity, for E.G the PH gets closer to 7

5. Formular

   • Metal + oxygen = Metal oxide
   • Metal + acid = salt + hydrogen
   • Metal oxide + acid = salt + water
   • Metal carbonate + acid = salt + water + carbon dioxide
   • acid + metal hydroxide = salt and water
   • acid + metal carbonate = salt + carbon dioxide + water
   • Acid + Base = salt + water
   • Acid + metal = salt + water
   • hydrogen + carbon = carbonate dioxide

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